Partridge Flashcards

Question

What are 2 subpops in cell mediated (T cell) immunity?

Answer 1

- T helper cells (CD4 +ve) | - T cytotoxic cells (CD8 +ve)

Answer 2

- help B cells make antibody - activate macrophages and NK cells - help dev of cytotoxic T cells

Answer 3

- recognise and kill infected host cells | - act a bit like NK cells, but much more specific (only kill those infected by particular type of infection)

Answer 4

- most act locally | - but can have systemic actions

Answer 5

- small (5-20kDa) secreted glycoproteins involved in communication between cells of immune response - immunomodulators --> usually prod and act locally, bind to specific cytokine receptors on target cells - secreted in response to immune activation - pleiotropic = diff effects on diff cell types - stimulatory and inhibitory - synergy or antagonism - redundancy

Answer 6

- interleukins (eg. IL-1, IL-38, IL-39) --> usually made by T cells - interferons (IFNs) --> some prod by any cell in response to infection, eg. IFNα, IFNβ and some prod by immune cells for cell activation, eg. IFNγ - chemokines --> cell movement or chemotaxis, eg. IL-8

Answer 7

- 1° = lymphocytes reach maturity | - 2° = mature lymphocytes stimulated by antigen

Answer 8

- oldest form --> elements shared by plants, insects and mammals, changes on evolutionary timescale - always available --> prior exposure not req and little/no memory - major form of immunity in young children --> approx 6 month period between loss of maternal antibodies and formation of own

Answer 9

- innate crucial role in initiating and directing adaptive, and dictating type of response adaptive mounts - adaptive take 4-6 days to dev, so innate critical in controlling infections before this (takes time for B and T to recognise antigen and divide)

Answer 10

- failure to dev immunity for organisms that mutate quickly (antigenically unstable), eg. parasites, influenza, HIV

Answer 11

pathogen preventative barrier --> no infection - FAIL- infection pre-formed broadly specific effectors --> pathogen removed - FAIL - innate cells recruited = early induced innate response (4-96 hrs) recognition, activation, inflammation --> pathogen removed - FAIL - antigen - lymphoid tissue recognition by naive B and T cells = adaptive immune response >96 hrs clonal selection - effector cells --> pathogen removed

Answer 12

- in all epithelial cells joined by tight junctions | - in resp tract cilia to move mucus and in others flow of air or fluid

Answer 13

- in skin FAs - in GI tract low pH and enzs (pepsin) - in UG and resp tracts lysozyme

Answer 14

- in all antibacterial peptides (defensins) and commensals (microbiota)

Answer 15

- make unfavourable env for pathogens

Answer 16

- generally impermeable (unless damaged by burn/cut/insect bite etc.) - keratinocytes prod keratin, ebum (contains FAs and defensins - shedding - commensals

Answer 17

- largest interface w/ env, semi-permeable (eg. gut, needs to take up nutrients) - mucus, cilia (resp tract) and secreted enzs (eg. lysozyme in tears and saliva - low pH (gut, vagina), peristalsis (gut) - shedding of epithelia - commensals

Answer 18

- lysozyme --> breaks bond in peptidoglycan, more active against Gram +ve bacteria - antimicrobial peptides --> eg. defensins, cathelicidins, histatins, all made as inactive precursors - defensins --> large group peptides 25-30 AAs long, 3 subfamilies w/ activity against diff types of pathogens, amphipathic and disrupt lipid bilayer

Answer 19

- >30 soluble proteins found in blood and other bodily fluids - discovered as heat sensitive substance that could "complement" immune sera (antibodies) in killing bacteria (inactive at high temps)

Answer 20

- components normally inert, but activated by presence of pathogens or antibody bound to pathogen * DIAG* - central event is cleavage of C3, by C3 convertase

Answer 21

- C1, 4, 2, 3, 5, 6, 7, 8, 9

Answer 22

- as part of innate immune response

Answer 23

- provides protection early in infection in absence of antibodies through other "older" activation pathways

Answer 24

- mainly made in liver | - C3

Answer 25

- Ser proteases, act on 1 another to gen larger and smaller fragment - C3 --> C3b + C3a - b is larger and a is smaller

Answer 26

- exposes reactive thioester in C3b, which can bind covalently to adj proteins/carbs, eg. on pathogens surface (rapidly inactivated in fluid phase

Answer 27

- classical pathway - mannose-binding lectin (MBL) pathway - alt pathway * DIAG

Answer 28

- for classical and MBL = C4bC2a (from cleavage of C4 and C2 by C1r,s and MASP2, respectively) for alt = C3bBb

Answer 29

- most abundant component - some gen spontaneously in body fluids by "tickover" mechanism --> but usually hydrolysed and inactivated quickly - if C3b gen binds to pathogen surface, factor B binds, which is cleaved by factor D to C3 convertase - C3bBb convertase stabilised by factor P (properdin) - C3b gen by classical or MBL pathway can also bind factor B - in alt pathway can get amplification --> feeds into other pathways once activated

Answer 30

- C3 convertase + C3b --> C5 convertase --> C5 --> C5b, C6, C7, C8, C9 (membrane attack complex - MAC) - C5a disperses and C5b triggers rest of cascade

Answer 31

- can insert into cell membrane of Gram -ve bacteria and prod pores that allow entry of membrane damaging molecules, eg. lysozyme, and makes bacteria susceptible to osmotic lysis

Answer 32

- opsonisation --> C3b - activation of IS --> C5a (or C3a but not as active) - lysis of foreign cells --> MAC, esp C9

Answer 33

- binding of complement proteins or antibodies (=OPSONINS) to surface of pathogen, so phagocytes can recognise and bind

Answer 34

- chemoattractants and anaphylatoxins | - stimulate mast cells to induce inflammation at local level

Answer 35

- allergy causes widespread activation of mast cells throughout body - lots of histamine release - causing pressure on heart and lungs

Answer 36

- through MAC (C5b - C9) - C9 forms polymer to form pores in eg. bacterial cells - esp important for Gram -ve (as harder for complement to penetrate peptidoglycan in Gram +ve)

Answer 37

- "double edged sword" | - to prevent damage to host

Answer 38

- components rapidly hydrolysed in fluid phase - soluble and membrane bound reg proteins, eg. - -> factor H competes w/ factor B for C3b binding - -> C1 inhibitor inactivates C1 - -> carboxypeptidase N inactivates C3a and C5a - -> CD59 on host cells bind C9, preventing MAC formation

Answer 39

- increase risk of some diseases - age related macular degen (factor H) - paroxysmal nocturnal hemoglobinuria (CD59) --> body attacks own RBCs

Answer 40

- esp important in ec bacterial and fungal infection, but may be active against some viruses, eg. pox - interacts w/ adaptive IS --> classical pathway, aids clearance of immune complexes, role in activating B and T cells - controversial role in some autoimmune diseases and asthma

Answer 41

- 'frontline' of defence --> specialised cells embedded in tissues, eg. mast cells, tissue macrophages (particularly prevalent in lungs) - act as sentinel cells --> all cells capable of some level of innate immunity - help deal w/ early stages of infection

Answer 42

- innate encoded through germline genes --> passed on from gen to gen = pattern recognition receptors (PRRs) - adaptive assembled through lymphocyte dev --> can change during lifetime, genes newly assembled for B and T cell dev

Answer 43

- PAMPs (pathogen-assoc mol patterns) --> shared by many MOs, distinct from self, critical for survival/function - DAMPs (damage-assoc mol patterns) --> released during injury and cell damage

Answer 44

- both relatively invariant structures

Answer 45

- bacteria = flagellins, unmeth CpG DNA, N-formylated proteins - gram -ve bacteria = lipopolysaccharides - gram +ve bacteria = lipoteichoic acid - fungi = chitin, beta-glucans - viruses = dsRNA - protozoa = GPI-linked proteins, mannose-rich glycans

Answer 46

- fragments of ec matrix proteins, eg. fibronectin - phosphatidylserine - heat shock proteins - mito components (if cell dying) - uric acid --> formed by purine build up in times of stress - DNA - HMGB1

Answer 47

- soluble factors, eg. mannose-binding lectin, complement - membrane receptors, eg. lectin, scavenger, chemotactic and toll-like receptors - cytoplasmic receptors, eg. NOD-like receptors (NLR) - membrane and cytoplasmic expressed by immune and non-immune cells

Answer 48

- receptor binding may initiate uptake (phagocytosis), chemotaxis (cell movement) or signalling (changes in gene expression) - C-type (Ca dep) lectins, eg. dectin-1, macrophage mannose receptor - scavenger receptors, eg. CD14 (recognises LPS), recognise alt/damaged host proteins too - chemotactic receptors recognise chemoattractants - TLRs = sensors that signal MO presence, signal to body and cause changes in gene expression, eg. make cytokines/interferons

Answer 49

- bind chemoattractants that guide phagocytes to sites of infection and increase efficiency of intracellular killing - eg. f-met-leu-phe receptor, recognises N-formylated polypeptides (prod by bacteria) - eg. C5a receptor, binds complement fragment C5a - GPCRs --> binding signals chemotaxis, mediator release and prod of ROS and NO

Answer 50

- ancient pathogen recognition system - 10 in humans, each recognising distinct PAMP - cell surface receptors or endosomal - often function as dimers

Answer 51

- TLR-3 and dsRNA - TLR-4 dimer and LPS - TLR-5 and flagellin

Answer 52

* DIAG* - ec domain of TLR3 has horseshoe shape, formed by leu-rich repeats, inner surface has β-sheet structure and forms ligand binding domain

Answer 53

- signalling to nucleus to induce expression of inflamm cytokines and interferons

Answer 54

- NOD-like receptors (NLRs) --> large group that recognise bacterial components (eg. peptidoglycan, flagellin), signal expression of pro-inflamm cytokines and trigger assembly of inflammasomes - RIG-I like receptors --> viral sensors that detect viral RNA prod w/in cell signal expression of interferons

Answer 55

- protein complex needed to process procytokines --> activates components too toxic to be active all time, by cleavage

Answer 56

- redness - swelling - heat - pain

Answer 57

- release of inflamm mediators - dilation of arterioles, venules and capillaries - increased permeability and blood flow - immune cell migration into inflamm focus - endothelial cells retract slightly allowing fluid through - sensidise nerve endings

Answer 58

- ensure immune cells, defence mols, coagulation factors etc. reach site of infection or tissue damage

Answer 59

- cells already in in tissues ready to respond - lipid mediators, eg. prostaglandins (prod inhibited by aspirin) - chemoattractants, eg. f-met-leu-phe - complement proteins, eg. C5a - vasoactive amines, eg. histamine, bradykinin - clotting factors - small molecules, eg. ROI, RNI

Answer 60

- movement of leucocytes from blood to tissues

Answer 61

- cytokine signalling mols made by damaged cells stimulate endothelial cells to express adhesion mols --> 1st are selectins - selectins capture neutrophils, which begin to roll along vessel wall - leucocytes express integrins that can bind to adhesion mols on endothelial cells - neutrophils squeeze between endothelial cells

Answer 62

- bacteria infect tissue - macrophages engulf bacteria and release chemical mediators - cytokines induce selectins on capillary endothelia that bind to neutrophils - vasoactive factors induce integrins on neutrophils, which bind ICAM and VCAM - bradykinin loosens junctions to allow extravasation and triggers prostaglandin synthesis - peptides from bacteria and chem signals from infected tissues released and attract neutrophils

Answer 63

- generally beneficial in dealing w/ infection/injury | - avoided in some places where would be harmful, eg. brain, CNS

Answer 64

- caused by chronic inflammation, eg. TB, autoimmune disease | - can be damaging

Answer 65

- can survive in macrophages | - chronic inflamm could be good, as bacteria encapsulated, so can't spread to rest of body

Answer 66

- grouped into fams based on structural similarities | - but fam members may have distinct functions

Answer 67

- binding of cytokine to receptor can cause changes in gene expression and cell activation (or in some cases cell inhibition), or induce cell movement - many are dimeric enz-coupled receptors - chemokine receptors are GPCRs

Answer 68

- by macrophages and dendritic cells in early induced immune response

Answer 69

- as TM protein, released by proteolysis - primarily by macrophages - LPS is potent stimulus of its prod

Answer 70

- TNFR1 major form - TNF trimer cross-links 3 receptors - 2 pathways --> cell stim/apoptosis

Answer 71

- too toxic

Answer 72

- influx of platelets --> clotting in capillaries helps prevent spread of infection - microthrombosis --> link between inflamm and coronary thrombosis - efflux of fluid from capillaries --> increased flow to lymph nodes and stim of adaptive immunity

Answer 73

- <1µg/ml --> enough to activate receptors all over - pyrexia (fever) --> acts of hypothalamus, inhibits growth of some bacteria/viruses, 39.5° optimum temp for B and T cell activation - cachexia (muscle wasting) --> presumably protective response to infection, cancer, trauma

Answer 74

- at concs >1µg/ml - widespread increase in vascular permeability --> hypotension - disseminated thrombus formation --> myocardial infarction and organ damage - consumption of clotting factors --> internal bleeding and spread of infection - multiple organ failure - septic shock (80% lethal)

Answer 75

- interfere w/ viral rep

Answer 76

- type I = IFNα (12 genes in humans), IFNβ - -> many cell types can be induced to make after viral infections (induced by eg. RIG-I) - -> some cell types (eg. dendritic cells) specialised for this, express high levels of endosomal TLRs. eg. TLR3, TLR9 - type II = IFNγ

Answer 77

- induce expression of endoribonuclease that degrades viral RNA and protein kinase that phosphorylates euk initiation factor 2, inhibiting protein translation - increased MHC class I expression and antigen presentation in all cells --> so infected cells recognised by cytotoxic T cells more easily - activate NK cells to kill virus-infected cells (uninfected cells protected by increased MHCI) - induce expression of chemokines --> attract other cells to site of infection - if signal goes on long enough, triggers apoptosis of neighbouring cells --> barrier to virus rep

Answer 78

- poss to make recomb or synthetic versions | - have some ability to induce apoptosis of tumour cells, so could be used for this

Answer 79

- made by neutrophils, NK cells, T cells - 1° role in adaptive (also some role in innate) - important in neuronal cells - anti-viral response by restricted range of cells - activation of macrophages in TH1 response

Answer 80

- dep on cytokines they make | - TH1 (inflamm cytokines) and TH2 cells

Answer 81

- prod IL-2, IFNγ, TNFα - activate macrophages and induce B cells to make opsonising antibodies (IgG) - in classical bacterial and viral infections

Answer 82

- prod IL-4, 5, 6, 10, 13 - induce B cells to make IgE (4 and 13) - in parasitic infections

Answer 83

- diff antigens/pathogens induce cells of innate IS to prod diff cytokines - act on adaptive IS to prod approp response - selection of wrong response can lead to disease

Answer 84

- many shaped nuclei

Answer 85

- neutrophils --> didn't take up acidic or basic dye - eosinophils --> took up red dye strongly, as v acidic - basophils --> took up basic stain

Answer 86

- neutrophils

Answer 87

- <6% leucocytes in blood - also in connective tissue under mucosal surfaces - receptors for C3b, IgG, IgA (and IgE can be induced, but not naturally) - defence against parasitic infections (too big to phagocytose) - release toxic proteins and free radicals from granules - synthesise cytokines (eg. IL-40) and prostaglandins - role in allergy --> esp asthma, contrib to chronic inflamm

Answer 88

- <1% leucocytes in blood - similar to tissue mast cells (but free to roam and enter tissues when needed) - receptors for C3a, C5a, IgE (high affinity IgE) - release heparin and histamine - make IL-4 and IL-13 - defence against parasites, role in allergy

Answer 89

- stops blood clotting too quickly

Answer 90

- vasodilator, important in early stages of infection

Answer 91

- restricted to tissues, protect mucosal surfaces - receptors for C3a, C5a, IgE - release histamine etc. and make IL-4, IL-13 - sentinel cells - defence against parasites - role in allergy

Answer 92

- 50-60% of leucocytes in blood - huge no.s can be released from bone marrow - last <24hrs in blood (unless infection present) - death by apoptosis (and destroyed by macrophages in spleen etc.) - life extended on entering tissues (extravasation in response to chemoattractants) - found in large no.s in pus

Answer 93

- phagocytosis - release of anti-microbials, eg. lysozyme, defensins - prod of ROIs --> kill and act as inflamm mediator - prod of cytokines - entrapment of MOs --> form NET (neutrophil ec trap)

Answer 94

- to move into tissue and differentiate into macrophages (circulate in blood approx 3 days)

Answer 95

- sentinel cells --> bacterial invasions, dust/particles - express wide variety of PRRs - high phagocytic ability = 100 bacteria/cell - driven by scavenger, mannose or complement receptors - prod of pro-inflamm mediators (TNF, IL-12, IL-16, IL-1β)

Answer 96

- antigen presentation to T helper cells - T cell activation of macrophages - interferon γ - antibody-dep cell med cytotoxicity (ADCC) - receptors for IgG, IgA (antigen specific phagocytosis)

Answer 97

- bacteria binds to surface of phagocyte (can be aided by antibody or complement) - pseudopods extend and engulf organism - invagination of phagocyte membrane traps organism w/in phagosome (some bacteria learnt to escape into cyto) - lysosome fuses and deposits enzs into phagosome, enzs cleave macromols and gen ROS, destroying the organism

Answer 98

- acidicification = pH 3.5-4, bacteriostatic or bacteriocidal - toxic O derived prods = O free radicals - toxic NOs = NO - antimicrobial peptides = defensins and cationic proteins - enzs = lysozyme (dissolves cell walls of some Gram +ve bacteria), acid hydrolases (further digest bacteria) - competitors = lactoferin (binds Fc) and vit B12 binding protein

Answer 99

- mechanism of killing by free radicals - "resp burst" = transient increase in oxygen, following phagocytosis, due to activation of membrane bound NADPH oxidase - ROI: superoxide (.O2-) hydrogen peroxide (H2O2) hydroxyl radicals (.OH) hypochlorite (OCl-) hypochlorous acid (HOCl) = bleach

Answer 100

- prod by iNOS2 (inducible nitric oxide synthase) | - NO can kill large variety of pathogens and precursor for other RNS, eg. NO2- (nitrite) and ONOO- (peroxynitrite)

Answer 101

- insert into plasma membrane via perforin - perforin similar to C9 (last component of complement) and like C9 forms hollow cylinder, perforates target cell and enzs from granules go through and enter target cell - inducing apoptosis of target cell

Answer 102

- viral infections | - but also intracellular bacteria and protozoa

Answer 103

- helps keep viral infections in check before adaptive IS takes over - source of IFNγ - can use ADCC to kill infected and cancer cells - receptors for IgG

Answer 104

- activity controlled by opposing stim and inhib receptors - programmed to kill unless get signal from cell that it is self - stimulatory = natural cytotoxicity receptors (NCRs), ligands inc nectin fam (polio virus receptors) - inhibitory = killer Ig-like receptors (KIRs), eg. MHCI (=self labels expressed by all nucleated cells)

Answer 105

- to evade cytotoxic T cells, even though still killed | - as worse death than by NK cells

Answer 106

- heterogenous pop of cells in skin and lymphoid tissues - take up foreign material by phagocytosis/macropinocytosis - transport antigen to lymphoid tissue - present digested antigen to T lymphocytes - constitutively express high levels of MHCII proteins

Answer 107

- uptake of fluid and any foreign material in it | - all cells capable, but esp done by dendritic cells

Answer 108

- recognises infection (non-self or antigen) or danger - following 1° contact w/ antigen there are innate and weak adaptive responses - 2° contact = enhanced adaptive responses (immunological memory) - contains and eliminates infections through effector functions - must be reg and tolerant of body's own cells and mols

Answer 109

- macrophage/dendritic cell takes up foreign material - transported to nearest draining lymph node --> where just matured B and T cells tend to congregate - presentation of antigen to T cells, activating them - B cells activated and differentiate into plasma cells (make antibodies) - antibodies and activated T cells (= effector T cells) can go out into tissues and deal w/ infection

Answer 110

- long lived, in some cases life long, and provide immunity

Answer 111

- millions of cells made w/ diff receptors --> gen indep of antigen - any lymphocytes that recognise self deleted early in dev - if get infection w/ antigen recognised by receptor, that cell undergoes clonal selection --> get 100s-1000s cells from 1 parent w/ same receptor - some B cells differentiate into plasma cells to make antibodies - also get gen of long lived memory cells

Answer 112

- antigen recognition = as integral membrane proteins on B lymphocytes, Fab regions - antigen elimination = as soluble proteins secreted by plasma cells, Fc region

Answer 113

* DIAG* - Fab regions variable in seq and bind diff antigens specifically - Fc region constant in seq, bind to complement, Fc receptors on phagocytes, NK cells etc.

Answer 114

* DIAG* - light (L) chain = 25kD - heavy (H) chain = 50kD - immunoglobulin G = L2H2 = 150kD

Answer 115

- proteolytic cleavage w/ papain = 2 Fab fragments and 1 Fc fragment - proteolytic cleavage w/ pepsin = 1 Fab fragment (attached via disulphide bonds) and Fc fragment extensively degraded

Answer 116

- AA seq of heavy chains

Answer 117

- kappa (κ) or lambda (λ) | - not class restricted, ie can have IgGκ or IgGλ antibodies

Answer 118

- protein seq | - eg. of myeloma proteins (cancer of plasma cells)

Answer 119

- contain constant and variable regions - comprised of homologous domains - variable region domains contain 3 hypervariable regions

Answer 120

- variable bind antigen, differ between antibodies w/ diff specificities - constant same for antibodies of given H chain class or L chain type

Answer 121

- approx 110 AAs w/ intrachain S-S bridge that fold to form compact globular domains - folding pattern known as Ig fold - cleavage needed, as hinge region not folded into compact domains, so quite floppy

Answer 122

- C domain has 7 β strands - V domain has 9 β strands - found in all members of Ig gene superfam

Answer 123

- involved in recognition, binding and adhesion - domains can be V-like or C-like, domain structure is v stable and therefore prevalent, β strands stable and loops can vary w/o disrupting other cell structure

Answer 124

- 765 | - members usually only found on cell surface as receptors

Answer 125

- 3x hypervariable regions (approx 7-12 AAs) | - rest is framework regions

Answer 126

- complementarity determining regions (CDRs) | - how complementary determines how specifically can interact w/ antigen

Answer 127

- non-covalent (electrostatic interactions, H-bonds, VdWs, hydrophobic interactions) - indiv weak, but if many form simultaneously (ie. if antigen combining site and antigen contain many complementary residues), then interaction specific and of high affinity

Answer 128

- most B cells express IgM (1st to be prod in antibody response) and/or IgD --> but all classes can serve as B cell receptor - recognises and binds to antigen, but cant prod signal itself - membrane bound Igs assoc w/ 2 other prots --> Igα and Igβ - Igα and Igβ contain single ITAM (immunoreceptor Tyr activation motif) in their long cyto domains

Answer 129

- only expressed on membranes, not as soluble proteins

Answer 130

- cytotoxic = specifically kill infected host cells | - helper = augment immune response

Answer 131

- T cell immunity for intracellular pathogens, so recognise "cell-assoc", free, native antigens - T cells recognise processed peptides presented to them on cell surface by major histocompatibility proteins (MHC)

Answer 132

- MHCI = expressed by all nucleated cells, present peptides derived from endogenous proteins - MHCII = expressed by certain leucocytes (dendritic cells, B cells, macrophages), present peptides derived from exogenous proteins

Answer 133

- cytotoxic T cells recognise peptide bound to it | - virus infected cell makes virus proteins, broken down in cytosol, peptides transported to ER and bind MHCI on surface

Answer 134

- helper T cells recognise peptide bound to it - antigen presenting cell internalises and breaks down foreign material, peptides bind to MHCII in endosomes on cell surface (cell not infected, just needs help dealing w/ infection)

Answer 135

- Fab like --> disulphide bond holding together and some flexibility (like hinge region) - ec domains homologous to V and C regions of Ig --> each V region has 3 hypervariable regions of CDRs

Answer 136

- γδ receptors - in 1-5% T cells - found at epithelial surfaces - less diverse --> recognise broader range of antigens

Answer 137

- complex of antigen and self MHC

Answer 138

- CDR3 regions of α and β chains most variable --> bind foreign peptide - CDR1/2 bind self MHC

Answer 139

- v short C-ter, so don't protrude much into cyto, so can't signal by itself, needs to assoc w/ diff membrane proteins

Answer 140

- α and β subunits (TCR) | - CD3 subunits (ε, δ and γ) and ξ --> CD3 subunits contain ITAMs in their cyto regions

Answer 141

- approx 10^14 antibody receptors and 10^18 T cell receptors

Answer 142

- variation in seq and length of CDRs are main determinants of antibody diversity - CDR3 tends to be most variable in length and seq - heavy chain generally contributes more to antigen binding and more variable than light chain

Answer 143

- multiple genes - somatic mutation --> not pop to have mutations in somatic cells - somatic recomb --> not pop to have genes in fragments

Answer 144

- Igs encoded by separate C region and multiple V region genes

Answer 145

- Ig genes rearranged during B cell dev --> proven through restriction digests

Answer 146

- used mouse embryo and mouse myeloma cells - DNA extracted and digested w/ REs - restriction fragments separated by gel electrophoresis - V and C regions identified by hybridisation w/ radioactive probes - in myeloma both probes bound same region --> so must have been recomb event so V and C lying close together - embryo pattern (V and C probes bound separately) in all cells, except those of B lineage

Answer 147

- heavy (H) chains = chromosome 14 - kappa (κ) chains = chromosome 2 - lambda (λ) chains = chromosome 22

Answer 148

- each locus has multiple variable region genes and 1, or a few constant region genes - V regions encoded by 2 or more exons

Answer 149

- by 2 segments of DNA * DIAG* - most encoded by V segment - there is also joining segment

Answer 150

- by 3 segments of DNA * DIAG* - V segment, diversity and joining

Answer 151

- Cμ (IgM heavy chain)

Answer 152

- somatic recomb = V gene spliced to J gene and intervening DNA excised - rearranged V promoter now close to enhancer allowing transcrip - intervening seqs removed by RNA processing - end up w/ mRNA corresponding to particular V and J region, and C region

Answer 153

- D-J joining - then V-D-J joining - all extra bits removed when transcribed to mRNA

Answer 154

- CDR1 and CDR2 encoded by V segments (ie. germline) | - CDR3 corresponds to VDJ (or VJ for light chain) join

Answer 155

- involves lymphocyte specific recombinases and conserved recognition signal seqs (RSSs) - RSSs guide recomb, make sure correct order and don't get misjoining - 12-23 bp rule

Answer 156

- conserved heptamer (7bp) and nonamer (9bp) separated by 12 or 23 random nucleotides - found directly adj to coding seq of V, D or J gene segments

Answer 157

- gene segment w/ 12bp spacer only joins w/ gene segment w/ 23bp spacer - 12bp and 23bp spacer correspond to 1 and 2 turns of DNA helix

Answer 158

- complex of several enz req for somatic V region gene recomb --> normal DNA cleavage/repair enzs, inc DNA-dep protein kinase - products of Rag-1 and RAG-2 genes (recombination activation genes) - terminal deoxynucleotide transferase (TdT)

Answer 159

- severe combined immunodeficiency (SCID)

Answer 160

- bone marrow transplant | - genetic techniques

Answer 161

- RAG-1/RAG-2 complex recognises and aligns RSSs adj to gene segments to be joined (germline DNA folded) - 2 ssDNA breaks made close to RSSs - free 3' OH attacks phosphodiester bond on other strand DNA to create hairpin at segments to be joined and flush ds break at RSS boundary - other proteins bind to repair joints, but imprecise, w/ nts added/subtracted - -> DNA hairpins claved at random, symmetrically or asymmetrically - -> for VDJ joining of H chain, nts can be added in a template indep, by TdT - -> unpaired overhangs filled in by DNA pol or may be excised by endonuclease - DNA ligase joins nicked and repaired hairpins to form "coding joint" (blunt ends ligated to form "signal joint" and typically excised)

Answer 162

- looks a bit like a pair of scissors - hinge region and flexible pair of domain that bind nonamer => NBD (nonamer binding domain) - structure tilts, so if bound to RSS w/ 12bp spacer, will now bind 23bp spacer

Answer 163

- heavy chain rearrangement (D-J, then V-D-J) --> μ heavy chain - light chain gene rearrangement (V-J) --> expresses membrane IgM - selection against self recognising cells - in 2° lymphoid tissue naive B cell expresses membrane IgM or IgM and IgD

Answer 164

- apoptosis

Answer 165

- bone marrow

Answer 166

- 2° lymphoid tissue

Answer 167

- somatic hypermutation | - class switching

Answer 168

- point mutations introd in rearranged V regions - mechanism is activation induced cytidine deaminase (AID) --> mutations introd t/o V regions, but in mature B cells mutations clustered in CDRs

Answer 169

- enz expressed only by B cells in lymphoid tissue responding to antigen

Answer 170

- main role to improve immune response | - but can also add diversity

Answer 171

- higher affinity receptors selected as immune response proceeds --> "survival of the fittest"

Answer 172

- 1bp per 10^3 bp per cell division | - normal = 1bp per 10^10 bp per cell division

Answer 173

- IgM --> IgG, IgA etc. - same recombined V region assoc w/ diff C region genes - antigen specifically retained, but diff localisation/effector functions induced --> flexible response to pathogens - by DNA recomb between switch regions --> irreversible and intervening DNA lot - can get sequential switchin

Answer 174

- T cell help | - AID

Answer 175

- initiated by AID acting at switch regions --> G rich tandem repeated DNA seqs found close to C region genes

Answer 176

* DIAG* --> deaminated C to form U - AID expressed in activated B lymphocytes, only active on ssDNA - activity triggers DNA repair pathways (mismatch repair, base excision repair) - ie. not intro of U itself that causes mutation, its the repair pathways - repair pathways in B cells error prone, leading to diff mutational outcomes - -> mismatch/base excision = somatic hypermutation - -> ss nicks to ds nicks (common in G-rich tandem repeat switch regions) = class switching

Answer 177

- prior to class switching B cells may express diff classes by differential transcript processing and splicing - allows simultaneous membrane expression of 2 classes --> usually IgM and IgD (but can get IgM w/ any other class) - reversible, as no change in DNA

Answer 178

- differential processing of 1° transcript - at C-ter of IgM 2 diff exons --> 1 encodes hydrophobic residue, and other a hydrophilic residue - dep on which polyadenylation site used, decides which --> so whether can sit on lipid bilayer (hydrophobic) or exported and secreted (hydrophilic) - as B cells become activated, secreted form predominates

Answer 179

- look like antibody genes - chromosome 14 has 1 C region for α chain - chromosome 7 has 2 C regions for β chains --> v homologous, don't know function of having both

Answer 180

- somatic recomb of TCR V region genes --> same machinery as used in dev B lymphocytes - only diff is occurs in thymus

Answer 181

- mutliple copies of V region gene segment (Vn x Jn / Vn x Dn x Jn) --> α, β, γ (α-like) and δ (β-like) - α x β chain conformation (Vα x Jα) x (Vβ x Dβ x Jβ) = approx 6 x 10^6 - junctional diversity = approx 2 x 10^11 - -> conc in CDR3 of TCR α and β chains - -> total diversity = approx 10^18

Answer 182

- 1-5% of T cells - also gen by gene rearrangement - fewer V region gene segments, junctional variability (focussed at CDR3) may compensate to some extent --> but less diverse, recognise broader range of antigens, inc lipids - do not appear to req processing or presentation by MHC --> receptors more "antibody-like"

Answer 183

- encoded by genes of MHC chromosome 6

Answer 184

- HLA = human leucocyte antigen | - eg. HLA-A, HLA-B, HLA-C

Answer 185

- v polymorphic - eg. >1400 alleles of HLA-B locus - alleles may differ by up to 20 AA substitution - polymorphisms clustered in distal peptide binding domains (variability inherited, 1 person only has few diff variants of these alleles)

Answer 186

- T lymphocytes can only recognise antigen in context of self MHC molecules

Answer 187

- via experiments w/ inbred mice (identical MHC alleles) and virally infected cells (in vitro) - cytotoxic T cells from mouse A could kill infected cells - cytotoxic T cells from mouse B (even though from mouse immune to virus) couldn't kill cells taken from mouse A

Answer 188

1) 2 receptors on T cells - 1 (TCR) for antigen and 1 for MHC 2) 1 receptor on T cells (TCR) - recognises antigen and MHC - -> proof from X-ray crystallography

Answer 189

- MHCI = polymorphic TM α chain and invariant β2-microglobulin - MHCII = polymorphic TM α and β chains

Answer 190

- membrane-prox domains Ig like | - membrane distal domains bind peptides and contain polymorphisms

Answer 191

>> particular MHC molecule can bind wide range of related peptides MHCI: - bind peptides 8-10 AA long - N and C-ter bind to invariant sites at end of groove - 2/3 anchor residues on peptide bind to specificity pockets formed by polymorphic residues MHCII: - bind peptides 13-25 AA long - peptide backbone interacts w/ conserved residues that line groove - side chains (anchor residues) interact specifically w/ specificity pockets formed by polymorphic residues along peptide binding groove

Answer 192

- demonstrated MHC binds peptide - that TCR recognises complex of peptide and self MHC - MHC molecules have broad specificity for peptides (degenerate specificity) - bound peptide is integral part of MHC structure

Answer 193

- dissoc v slowly - if not bound, doesn't fold correctly and not transported to cell membrane correctly - important in immune response, so want it to be displayed as long as poss

Answer 194

- peptides transported to ER by ATP hydrolysis driven transporter, TAP (transporter assoc w/ antigen presentation) - peptides loaded onto MHCI in ER (req chaperones) - peptide binding essential for MHCI cel surface expression

Answer 195

- antigen taken up by phagocytosis or endocytosis etc. - acidification promotes folding and proteolysis - peptides assoc w/ MHCII in endocytic compartment

Answer 196

- process by which certain antigen presenting cells, eg. dendritic cells, present peptide assoc w/ MHCI to cytotoxic T cells

Answer 197

- TCR must assoc w/ other cell surface receptors (CD3 and ζ chain) to signal

Answer 198

- stabilise interaction - facilitate signalling - CD8/4 interact w/ invariant regions on MHCI/II - MHCI + antigen CD8 - MHCII + antigen CD4

Answer 199

- phosphorylation of ITAMs by receptor assoc kinase - when co-receptor binds to MHC ligand, ZAP-70 binds to phosphorylated ζ chain ITAMs and phosphorylated by Lck (Y kinase)

Answer 200

- co-dominantly --> increasing no. diff MHC molecules expressed per cell - MHCI most variable

Answer 201

- graft rejection (recognised as foreign, unless identical twin) - ensures wide recognition of foreign peptides - but variability of MHC mols small compared to that of TCR - T cell responses determined by individuals MHC type (MHC restriction) --> responders and nonresponders (may get pathogen that can't prod any peptides which bind MHC, happens in inbred mice strains, but rare in humans as not inbred) - each MHC allele can bind restricted range of related peptides

Answer 202

- pathogens | - eg. black death/flu/HIV ??

Answer 203

- greater social interaction | - and therefore chance of passing on diseases

Answer 204

- graft rejections - T cell activation - antigen presentation to T cells - self/non self recognition (NK cell KIR = killing inhibitory receptors) - assoc w/ certain autoimmune diseases --> eg. MS, Graves disease - dev of T cell repertoire/tolerance in thymus - choice of mate?

Answer 205

- someone w/ MHC proteins as diff as poss

Answer 206

* DIAG* - bone marrow stem cell is double -ve (CD4-/CD8-) - rearrangement of TCR genes (γδ or αβ) - get TCR w/ double +ve (CD4+/CD8+) - MHC selection (αβ) - +ve selection and any cells that don't bind self MHC rejected and undergo apoptosis - -ve selection and any cells that bind self MHC and self peptide strongly rejected and undergo apoptosis - AIRE (autoimmune regulator) allows expression of proteins in thymus usually expressed elsewhere - result is single +ve (CD4+ OR CD8+)

Answer 207

- diff Ig classes have diff biological roles | - way they deal w/ pathogens is dep on class

Answer 208

* DIAG* - monomeric - mw = 150,000d - subclasses = IgG1, IgG2, IgG3, IgG4 --> differ mainly in length and no. disulphides of hinge region (rest is homologous) - C2 faces covered by carb so not touching - extended hinge region --> v flex and susceptible to proteolysis

Answer 209

- main antibody in tissues and blood - can activate complement - bind Fc receptors on phagocytes and NK cells --> IgG1 and IgG3 most active in this and complement activation, due to residues and longer hinge region - crosses placenta --> binds FcRn on trophoblast - long serum half life - important in 2° or "memory" responses

Answer 210

* DIAG* - pentamer --> 5 antibody units and J chain - mw = 970,000d - no defined hinge = "functional hinge", so not as much flex

Answer 211

- usually serum restricted (unless inflam and vessels get leaky) - high valency --> can usually only bind 5 antigens at once, but good agglutinator of particular antigen - most efficient class at activating complement - important in 1° antibody response --> doesn't undergo somatic mutation so lower affinity (but higher avidity)

Answer 212

* DIAG* - monomer in serum and usually dimer in secretions - subclasses = IgA1 and IgA2 - in secretions and at mucosal surfaces forms secretory IgA = IgA dimer + J chain + secretory component

Answer 213

- helps protect from digestion and can bind mucin to anchor IgA to mucus

Answer 214

- high valency (binds 4 antigens at once, so good at clumping) - rapid catabolism - present in milk --> role in protecting newborn - does NOT activate complement --> exposed to foreign material in gut all the time, don't want big inflam response, just clumps bacteria together - binds Fc receptors on phagocytes

Answer 215

- mucosal lymphoid tissue prod 5g IgA per day - poly-Ig receptor binds polymeric IgA/IgM (normally IgA) - allows secretion of IgA (and IgM) into lumen - bacteria that penetrate mucosa can be transported back to lumen

Answer 216

* DIAG* - monomeric - mw = 184,000 - long extended hinge, heavily glycosylated

Answer 217

- <1% serum Ig - function still not entirely understood, but v conserved in evo - present as antigen receptor on many B lymphocytes, w/ IgM (may help B cells recognise antigen, as better hinge and flex than IgM) - prod by B cells/plasma cells in upper resp tract, interacts w/ receptors on basophils, inducing antimicrobial, inflam and B cell stimulatory factors

Answer 218

* DIAG* - monomeric - mw = 190,000d - no defined hinge --> "functional hinge" like IgM

Answer 219

- trace in serum (0.0003% Ig) - binds to high affinity FcR on mast cells and basophils - important in allergy - role in immune defence against large ec parasites, eg. helminths

Answer 220

- label pathogens --> elimination/destruction - specific binding/multivalency --> at least divalent - neutralise toxins (IgG, IgA) - immobilise pathogens (IgM) - prevent binding of pathogens to host cells (IgG, IgA) - agglutinate particles, eg. bacteria (IgM, IgA) --> so more easily wafted through body and less mobile - form "immune complexes" w/ soluble antigen

Answer 221

- if bind to transporter, but usually need to react w/ complement/leucocyte to kill

Answer 222

- invoke destruction of labelled pathogens - activate complement (IgM, IgG) - bind Fc receptors on leucocyte surfaces (IgG, IgA, IgE)

Answer 223

- site and type of infection | - stage of immune response (1° or 2°)

Answer 224

- antigen-antibody complex - 2x IgG molecules bound to bacterial cell surface, so C1q can interact w/ CH2 - C1q must interact w/ 2 Fc regions - need 2x C1q to bind to activate complement

Answer 225

- IgM pentameric, so C1q bind 1 molecule, rather than at least 2 of IgG

Answer 226

- pentameric IgM bind to antigens on bacterial surface and adopt 'stable' form (arms dislocate so no longer in same plane) - C1q binds to 1 bound IgM - binding of C1q activates C1r, which cleaves and activates C1s (both Ser proteases)

Answer 227

- bind to antigen on bacterial surface - C1q binds to at least 2 IgG molecules - binding activates C1r, which cleaves and activates C1s (both Ser proteases)

Answer 228

- inflam - activation of leucocytes (eg. for chemotaxis) - opsonisation - lysis of foreign cells

Answer 229

- immune defence against bacteria (and viruses), clearance of immune complexes - inducer of inflam, can cause pathology

Answer 230

* DIAG* | - when Ab and C3b coated best recognised, as phagocytes have receptors for both

Answer 231

- variety of effector cells | - inc granulocytes, mononuclear phagocytes, NK cells

Answer 232

- most function as part of a multi-subunit complex | - α chains bind Fc and assoc chains facilitate cell surface expression/signalling

Answer 233

- activation dep on FcR bound antibodies binding to antigen --> generally receptors quite low affinity, only activated when cross-linked - involves immunoreceptor Tyr activation motifs (ITAMs)

Answer 234

- inhibitory receptors contain immunoreceptor Tyr inhibitory motifs (ITIMs)

Answer 235

- differ in cytoplasmic/membrane spanning regions

Answer 236

- uptake of immune complexes - opsonisation - cell activation - resp burst (release of ROI) - release lysosomal contents ("frustrated phagocytes")

Answer 237

- IgG (IgG1 = IgG3 > IgG4) | - IgA

Answer 238

- IgG (IgG = IgG3)

Answer 239

- med ADCC (antigen dep cell-med cytotoxicity) - antibody binds antigens on surface of target cells - Fc receptors on NK cells recognise bound antibody - cross-linking of Fc receptors signals NK cell to kill target cell - target cell dies by apoptosis - occurs through binding of IgG coated target cells to FcγRIII --> NK cells release enzs and perforin from cyto granules

Answer 240

- intracellular receptor for IgG, IgM and IgA - meds humoral immunity - binds Ig w/ high affinity - recruits to internalised antibody bound virus and targets it to proteasome --> recognises viruses more efficiently - shown to neutralise virus infection in vivo

Answer 241

- neonatal receptor for IgG (IgG1 > IgG3 > IgG2 > IgG4) and present in neonatal gut - also in adults in gut, liver and endothelial cells

Answer 242

- placental receptor of IgG (on trophoblast), protects fetus and newborn - in adults binds and recycles IgG, preventing excretion (improves half life)

Answer 243

- med allergy/defence against large parasites | - mast cells secrete inflam mediators and cytokines

Answer 244

- make IgE instead of IgG - IgE binds to receptors on mast cells - if come across allergen again get cross linking of receptors ad v rapidly (5-10 mins) mast cell releases granule contents

Answer 245

- have no thymus, so no T cell responses | - survive reasonably well as have innate and some B cell response

Answer 246

- eg. bacterial polysaccharides - induce more rapid response and prod of IgM antibodies - memory cells not gen

Answer 247

- eg. proteins - for most antigens differentiation of B cells into plasma cells (or memory cells) us T cell dep - responses involve somatic hypermutation (leading to affinity maturation) and class switching following AID expression

Answer 248

- can influence slass/subclass of antibody prod in humoral response

Answer 249

- recognition of MHC + peptide + co-receptor - causes activation (signal 1) - TCR +CD3 + CD4/CD8 MHCII/I + peptide

Answer 250

- recognition of MHC + peptide + co-receptor (CD4/CD8) --> signal 1 - recognition of co-stimulatory molecules --> signal 2

Answer 251

- only dendritic cells, macrophages and B cells express co-stim molecules req to deliver 2 signals - dendritic prob most important in stim naive T cells

Answer 252

- T cells become unresponsive/tolerised

Answer 253

- B7 - expressed by dendritic cells, macrophages, B cells - interacts w/ CD28, inducing expression of IL-2 and IL-2 receptor - IL-2 acts in autocrine manner on T helper cells, also req for cytotoxic T cell activation - other cytokines direct T-cell differentiation into diff subsets of T effector cells (signal 3)

Answer 254

- dendritic cells and other innate cells | - varies dep on type of pathogen

Answer 255

- signal 3 = IL-12, IFNγ - prod IL-2, IFNγ, TNFβ - activate macrophages, causing inflam (classic cell-med immunity) - induce B cells to make more IgG1 and IgG3 (opsonising) antibodies - important for dev of cytotoxic T cells

Answer 256

- signal 3 = IL-4 - prod Il-4, 5, 6, 10, 13 - activate eosinophils and mast cells - induce B cells to make IgE (promotes mast cell degranulation)

Answer 257

- more than would expect

Answer 258

- signal 3 = TGFβ, IL-6 - prod IL-17, IL-22 - activates epithelial cells, fibroblasts - proinflam, esp at mucosal surfaces - recruit neutrophils to sites of infection, early in response - important in fungal and ec bacterial infections --> role in autoimmune disease?

Answer 259

- signal 3 = IL-6 - found in lymphoid follicles - help B cells differentiate into plasma cells and memory cells - promote somatic hypermutation - prod cytokines which prod AID (important for class switching and affinity maturation) - contact dep --> some go into germinal centres and physically interact w/ B cells - also prod IL-21 and other cytokines

Answer 260

- natural | - induced

Answer 261

- natural = thymus | - induced = periphery (mucosal lymphoid tissue)

Answer 262

- both CD4+, CD25+, FoxP3+

Answer 263

- natural = MHC and self peptide | - induced = MHC and non-self peptide

Answer 264

- natural = contact dep, IL-10, TGFβ | - induced = IL-10, TGFβ

Answer 265

- natural = dendritic cells, effector T cells | - induced = effector T cells

Answer 266

- natural = suppression of autoreactive T cells | - induced = downreg of mucosal immunity (dampens down immune response once pathogen destroyed), inflam responses

Answer 267

- if finds, makes cytokines to downreg immune response and stop any autoimmune response

Answer 268

- suppress immune response - selective prod of diff CD4 effector subsets can have sig consequences for type of immune response induced (influence Ig class, type of immune response or can downreg response)

Answer 269

- once activated, bind specifically to infected target cells and induce them to undergo apoptosis - naive cytotoxic T cells usually req co-stim from both dendritic cells (cross presentation) and effector T cells (TH1)

Answer 270

- release proteases (granzymes) that enter target cell via perforin channel - fas ligand induces clustering of fas ("death receptor") on target cell --> clustering causes activation of caspase cascade which induces apoptosis

Answer 271

- specific - efficient - "clean" --> no release of enz/toxins etc, and corpse removed by macrophages

Answer 272

- can prod some cytokines, eg. IFNγ and TNFα --> can synergise in activating macrophages - killing by fas pathway may be important in downreg immune response --> ie. may have suppressor function once immune threat dealt w/

Answer 273

- antiviral effects --> induces MHCI, enhances activity of immunoproteasome - recruits macrophages

Answer 274

- disease following immune response to innocuous antigen (=allergen)

Answer 275

- individual sensitised (2-3 wks) - -> IgE binds tightly to IgE FcR on mast cells (skin and mucus surfaces), basophils (blood) and activated eosinophils - -> no symptoms at this stage - immediate hypersensitivity reaction - -> 5-10 mins after re-exposure to allergen - -> cross linking of IgE by allergen on mast cell surface triggers release of inflam mediators

Answer 276

- smooth muscle contraction - increased vascular permeability - mucus secretion - platelet activation - stim of nerve endings - recruitment and activation of eosinophils (symptoms vary dep on where encounter antigen on body)

Answer 277

- insufficient exposure to certain types of infection ("dirt") skew TH1/TH2 balance towards TH2 - makes sense if look at interaction between TH1 and TH2 cells

Answer 278

- -ve correlation between helminth infections and allergic disease - would expect people responding to pathogens to be more prone to allergy, but opp true

Answer 279

- infection w/ MOs or parasites plays critical role in driving immunoreg - human IS and "old friends" co-evolved - infection protects against atopy by promoting IL-10 and TGFβ prod (TREG increase, and decrease in TH1/2) - so if not exposed to enough pathogen during IS dev, then don't get T suppressor cells - may also explain rise in autoimmune disease (TH1/2 driven)

Answer 280

- once antigen eliminated or infection cleared, 99% of activated and effector cells die - mechanisms of downreg = TREGs, cytotoxic T cells - inhibitory "immune checkpoints" expressed on lymphocytes, eg. CTLA-4 (induced on activated T cells) --> inhibits T cell activation - lymphocyte receptors w/ ITIMs - -> FcγRIIb on B lymphocytes (binds IgG and response switched off - -> PD-1 on activated B and T lymphocytes interacts w/ PD ligand (downreg of B and T cells as triggers phosphorylation of ITIM)

Answer 281

- 1 dimer of CD28 can only bind 1 B7 dimer (lower affinity/avidity) - CTLA-4 can interact w/ lots of B7 dimers at once, providing high affinity clustering

Answer 282

- used widely, as diagnostics and increasingly as new class therapeutic drugs - generally used to identify and label molecules in complex mixtures (blood/urine etc.)

Answer 283

- diverse (>10^9 specificities) - specific, high affinity (Kd 10^-8 - 10^-9M --> higher than most enzs for sub) - domain structure --> stable, facilitates engineering - multivalent --> increases avidity, cross-linking can be useful - effector properties --> useful in some techniques, therapeutics

Answer 284

- prod antisera (serum containing high levels of antibodies to target antigen) - can be purified and labelled w/ detectable tag

Answer 285

- fluorescent (eg. fluorescin) = immunofluorescence microscopy, FACS (fluorescence activated cell sorting) - enz --> coloured product = ELISA (enz linked immunoabsorbent assay), immunoblotting, immunohistology - radioisotope = radioimmunoassay, imaging of eg. tumours - gold particles = immuno-electron microscope - sepharose = affinity purification, immunoprecipitation

Answer 286

- as mol size <1000da | - as generally wouldn't stay in body long enough to cause response otherwise

Answer 287

- immunogenecity (=ability to induce immune response) - foreignness (=seq homology between antigen and equivalent protein in recipient) - mol size --> need carrier proteins - chemical composition --> aromatic groups, charged residues, some non-covalent interactions stronger than others - ability to provoke T cell responses (need carrier proteins) --> consider genotype of recipient (esp important in inbred mice - MHC) - use of adjuvants

Answer 288

- immunise animal - prod 2° response - collect serum

Answer 289

- product of several/many B cell clones (/lineages) - mix of antibodies specific to diff epitopes - instances where epitopes shared between antigens,s o could affect more than 1 antigen

Answer 290

- part of antigen where antibody binds

Answer 291

- cheap - robust (may recognise partially denatured/unfolded antigen) - form immune complexes well (good at cross-linking)

Answer 292

- poly-specific - need pure antigen to immunise - can be difficult to standardise

Answer 293

- 2° antibodies for immunoassays (may use monoclonal as 1°) - can cross react w/ diff mols, so see relationship between mols (eg. antibody isotypes) - identification of gene products, eg. dystrophin gene in Duchenne MD (ie. gene seq --> protein seq --> peptide -- > antibody

Answer 294

- have single specificity and derived from single B lymphocyte

Answer 295

- B cells from mouse immunised w/ antigen fused w/ myeloma cells - grow in drug-containing medium --> selection against unfused hybridoma cells as only hybrid cells survive (myeloma line deficient in enz for purine biosynthesis) - select for antigen specific hybridoma - clone selected hybridoma cells

Answer 296

- highly specific - can be standardised - pure antigen not needed for immunisation

Answer 297

- often conformation sensitive - less good at complex formation - expensive (tissue culture equipment and expertise)

Answer 298

- detect/quantitate diagnostically important molecules in clinical samples - eg. pregnancy/fertility testing, Down's syndrome testing

Answer 299

- eg. human leucocytes have CD (cluster of differentiation) classification system - identify cell types, eg. T cells (CD3) and subpops (eg. CD4, CD8) and stage of differentiation - functional studies --> antibody binding may inhibit, or activate (mimic natural ligand binding) - gene cloning --> identify gene products, screen expression libs

Answer 300

- if could use to recognise protein only found on cancer cells

Answer 301

- dev of antibiotics

Answer 302

- HAMA = human anti mouse antibody - at best monoclonal antibody not effective - at worst causes serum sickness

Answer 303

- antibody chimeras | - "humanised" antibodies

Answer 304

- mouse V regions and human C regions (C region most immunogenic) - mouse V regions still immunogenic - reasonably successful

Answer 305

- human framework regions and mouse CDR regions --> aka CDR grafting (CDR most important in binding antigen) - facilitated by Ig domain structure - overall folding pattern not disrupted

Answer 306

- may lose affinity/specificity (as framework regions can also be important in binding antigen) - time consuming

Answer 307

- iso mRNA from antibody prod cells --> blood, lymphoid tissue, bone marrow - amplify Fab of Fv cDNA by PCR (part that recognises antigen) - clone and express in bacteria/phage (phage display) - screen antibody phage display lib vs solid phase antigen "panning"

Answer 308

- most common vectors | - express soluble protein in bacteria or on surface of filamentous phage particles

Answer 309

- iso pop of genes encoding antibody V regions - construct fusion protein of V region w/ bacteriophage coat protein - cloning random pop of V regions gives rise to mix of bacteriophage = phage display lib - select phage w/ desired V regions by specific binding to antigens ("panning") - following selection, phage used to re-infect bacteria and process repeated to enrich for antigen binders

Answer 310

- genes optimised for expression in bacteria | - not real human genes, as codons swapped

Answer 311

- synthetic/semi-synthetic human antibody gene lib created - human V region genes and "randomised" CDR regions - >10^9 members - CDRs can be further mutated to improve specificity/affinity

Answer 312

- no adaptive I, can tolerate human leucocytes - so reconstituted w/ human lymphocytes using hybridoma techniques - can be immunised to gen human antibodies, but repertoire limited to that of human cells used

Answer 313

- mouse antibody genes replaced by human antibody genes ("xenomouse") - these genes introd using YACs - mice can be immunised t gen human antibodies by conventional monoclonal or phage display techniques - their IS works w/ human antibodies (seem healthy), but may have some problems as some effector sites diff etc.

Answer 314

- fully mouse (-omab) - chimeric (-ximab) - humanised (-zumab) - fully human (-umab)

Answer 315

- 2 forms - conventional --> H and L chains, both req for antigen stability and binding - and H chain antibody --> only H chains, full antigen binding capacity and v stable *DIAG*

Answer 316

- single domain antibody (VHH) - small (1/10 size of monoclonal antibody) - flexible formatting - highly potent, robust and stable - broad target applicability - multiple administration routes - ease of manufacture - speed of discovery

Answer 317

- neutralise toxins --> eg. anti-tetanus (pooled IgG), anti-snake venom - prevent/treat infection --> eg. resp syncytial virus (RSV)

Answer 318

- magic bullets to target cancer cells - eg. anti-CD52 antibodies (CAMPATH antibodies) --> recognises leucocytes, good activator of complement and ADCC, use in leukemias and lymphomas - eg. anti-HER2 antibodies (Herceptin) --> recognise HER2 (RTK expressed in high levels in ≈25% breast cancers)

Answer 319

- antigen specificity (finding something only on cancer cells) - antigen shedding - tumour cells inaccessible, esp if large - HAMA responses - other side effects

Answer 320

- depletion of leucocytes (eg. antibodies to CD52, CD3, CD4) --> organ transplantation, graft vs host disease, autoimmune disease - blocking of cytokines, cytokine receptors, soluble mediators (eg. antibodies to TNF-α, IL-1, IL-6, C5 or their receptors) --> inflam/autoimmune disease, allergy (antibodies to IgE, cytokines) - immune checkpoint inhibitors (eg. antibodies to CTLA-4, PD-1) --> dampen down IS after response

Answer 321

- to inhibit immune checkpoints, to avoid death

Answer 322

- prod cytokine that recruit TREGs - express PD-L - CTLA-4 induced on activated T cells, expressed constitutively on TREGs, higher avidity for B7, so switched T cells off (usually only towards end of immune response) - PD-1 (transiently expressed on activated T cells) interaction w/ PD-L also induces inhibition

Answer 323

- antibodies that block inhibitory immune checkpoints

Answer 324

- characterisation of immune checkpoints | - cancer therapy by inhibiting -ve immune cell regulation

Answer 325

- exploit antibody effector functions/binding | - label antibody w/ toxin/drug/prodrug/radionuclide

Answer 326

- tumour specific antibody --> antibodies bind tumour cell --> NK cells w/ FcR activated to kill tumour cells - tumour specific antibody (or fragment) conjugated to toxin --> antibody-toxin conjugates bind to tumour cell --> conjugates internalised, killing the cell - tumour specific antibody (or fragment) conjugated to radionuclide --> radioactive antibody binds tumour cell --> radiation kills tumour cell and neighbouring tumour cells

Answer 327

- immunotoxins --> retain antigen specificity, tag or replace Fc w/ toxin - eg. ricin, diphtheria toxin or BFL1

Answer 328

- sites for eg. C1q binding, FcR binding "mapped" to AA residues on Fc - antibody engineering to improve half life an effector functions (eg. ADCC, complement activation) - "glycoengineering" --> removal of fructose improves interaction w/ FcγRIII and therfore ADCC

Answer 329

- OTK3 - specificity = CD3 - for transplant rejection

Answer 330

- infliximab - specificity = TNF-α - for Crohn's disease, rheumatoid arthritis (inflam)

Answer 331

- herceptin (trastuzumab) - specificity = HER2 - for breast cancer

Answer 332

- nivolumab - specificity = PD-1 - for metastatic melanoma, non-small cell lung cancer

Answer 333

- CAR = chimeric antigen receptor | - T cells engineered to recognise tumour antigen

Answer 334

- T cells harvested from blood of patient w/ B cell tumour - CD19 is antigen expressed by acute lymphoma leukemia - retrovirus encoding anti-CD19 CAR infects T cells that are activated w/ antibodies to CD3 and CD28 - infected T cells express anti-CD19 CAR, fused to signalling domain - CAR expression and T cell activation in vitro overcomes req for MHC recognition

Answer 335

- individualised medicine

Answer 336

- if T cells could mutate in tissues, then danger of getting T cells that recognise self --> doesn't matter as much if B cells do, as req T cell help anyway - would no longer be able to recognise self MHC - TCRs don't need v high affinity, as always recognise antigen in context of self MHC --> whereas B cells prob soluble Ig which does need to bind tightly

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