Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

FBS2 > Immunity and Infection > Flashcards

Immunity and Infection Flashcards

(122 cards)

Start Studying
1
Q

What are the characteristics of the innate immune response?

A

Non-specific; used immediately or within several hours after exposure to antigen (0-4h); responds the same way every time; distinguishes between self and non-self; induces and directs the acquired immune response

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the components of the innate immune response?

A

Physical/anatomical barriers; secreted compounds (cytokines, antibacterial compounds, complements, natural antibodies); cellular components (phagocytes, NK cells)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

When, after exposure to the antigen, does the acquired immunity (adaptive immunity) begin?

A

> 96 hours

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How does the skin prevent entry of pathogens?

A

Secretes anti-microbial compounds (against E. Coli)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

How do tears, sweat and saliva prevent the entry of pathogens?

A

Contain lysozyme –> destroy bacterial cell wall

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How does the innate immune response recognise the pathogen?

A

Recognises PAMPs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How are gram negative and gram positive bacteria differentiated?

A

GRAM NEGATIVE: small peptidoglycan component, presences of outer membrane containing lipopolysaccharide (LPS): lipid A (PAMP part), O polysaccharide (tells you which type of bacteria it is)
GRAM POSITIVE: big peptidoglycan component, no outer membrane, teichoic and lipoteichoic acid present

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Which are the pattern recognition receptors (PRR)?

A
  1. Collectins (serum)
  2. Toll-like receptors (membrane)
  3. Nod-like receptors (cytoplasm)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are collectins and how do they work?

A

Family of proteins present in solution; collagen structure: interacts with effector parts of the immune system; lectin region: binds to sugar molecules on surface of pathogen (mannose)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are toll-like receptors and how do they work?

A 
Membrane bound receptors:
TLR1: gram+ bacteria
TLR2: gram+ bacteria + mycoplasma
TLR3: RNA virus (dsRNA)
TLR4: gram- bacteria
TLR5: flagellin
TLR6: micoplasma
TLR7: RNA virus (ssRNA)
TLR8: RNA virus (ssRNA)
TLR9: unmethylated CpG DNA
TLR10: ?
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are Nod-like receptors and how do they work?

A

Intracellular PRR; NOD-1 –> gram+ bacteria; NOD-2 –> all bacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Which are the effector mechanisms of the innate immune system?

A
  1. Complement
  2. Phagocytosis and killing
  3. Cytokines
  4. Activation of adaptive immunity
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How does complement work and for which pathogens is it important?

A

Important for bacteria; operate via cascade activated by 3 pathways (classical, MB-lectin, alternative); induce activation of C3 by C3 convertase:

  1. C4a, C3a, C5a: recruitment phagocytosis
  2. C3b: opsonization
  3. C5b, C6,7,8,9: membrane attack complex –> lysis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the key players in phagocytosis?

A

Macrophage: maturates from circulating monocytes, large numbers in GI tract, spleen, liver and lungs, long-lived
Neutrophil: found only in blood unless activated, short-lived

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the killing mechanisms of macrophages and neutrophils?

A

Neutrophils: reactive oxygen intermediates –> NADPH oxidase on surgace of phagosome forms hydroxil radicals and hypochlorite –> DNA damage and alterations in bacterial membranes
Macrophages: reactive nitrogen intermediates –> cytokines –> inducible NO synthetase –> conversion of O2 and L-arginine to NO and L-citrulline –> DNA damage and alterations in bacterial membranes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are cytokines?

A

Proteins that act as intercellular messengers, can be activating or deactivating
Innate response: mostly activating (IL1,6, TNF-alpha)
Adaptive: also deactivating

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are chemokines and what are some examples?

A

Class of cytokines with chemoattractant properties; promote inflammation by allowing cells to adhere to the surface of blood vessels and migrate to the infected tissue; pleiotropic; four families;
IL-8: produced by macrophages and endothelial cells –> recruits neutrophils to site of infection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are interferons and how are they classified?

A

They are a class of cytokines:
Type 1: IFNalpha and beta –> response in virally infected cells –> activate NK cells
Type 2: IFNgamma –> antimicrobial killing, mostly adaptive immune response

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the function of NK cells?

A

Kill virally infected cells and tumor cells, responsive to TNFalpha, IL-12; produce IFNgamma

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What are the functions of IL1,6, IL12, IL8 and TNFalpha?

A

IL-1,6 —> inflammation and fever
IL-12 —> CD4 T cell differentiation
TNF-alpha —> fever, macrophage activation
IL8 —> produced by macrophages and endothelial cells —> recruits neutrophils to site of infection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What are the 3 types of antigen presenting cells?

A

Macrophages, B cells, dendritic cells (usually present as immature round cells displaying PRR; maturation leads to dendrites and expression of MHC and CD molecules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is the structure of the T cell receptor and where are T cells developed?

A

Heterodimer: alpha and beta chain or gamma delta with variable and constant regions
Developed: thymus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the structure of the B cell receptor and where are B cells developed?

A

Two identical heavy chains and two identical light chains; two antigen-binding sites per antibody
Development: bone marrow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What are the timings for the primary and secondary responses in adaptive immunity?

A

Primary: 12 days
Secondary: 5-7 days

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
What are the variable regions of the heavy and light chains composed of?
Heavy chain variable region (chromosome 14): V, D, J | Light chain variable region: V and J only
26
What is gene rearrangement important for?
Combinatorial diversity and junctional diversity (terminal deoxynucleotide (TdT))
27
What are the two groups of T cells?
Cytotoxic T cells (CD8): secrete cytotoxic granules, T cell receptor is not needed after recognition of antigen Helper T cells (CD4): differentiate to produce different sets of cytokines (Th1, Th2, Th17, Treg)
28
What does B cell activation lead to?
Production of plasma cells --> secretion of antibodies
29
What is the structure of immunoglobulins?
Two heavy chains and two light chains; Variable region determines specificity (kappa or lambda); Constant region of heavy chain determines function of antibody (isotype)
30
Which type of bonds link the heavy and light chains of antibodies?
Disulfide bonds
31
What are the four functions of antibodies?
1. Neutralisation 2. Opsonisation 3. Activation of the component cascade 4. Agglutination of particles
32
What are the characteristics of IgG?
Main one in serum; response to vaccines; 4 subtypes; goes on to placent; opsonisation; activation of NK cells
33
What are the characteristics of IgA?
Serum: monomer Mucosal surfaces: dimer with joining J chain Important in the gut; agglutination and neutralisation; crosses placenta and found in breast milk
34
What are the characteristics of IgM?
First antibody made in immune responses; pentameric (10 possible binding sites); agglutination; too big to cross placenta; can activate complement cascade better than IgD
35
What are the characteristics of IgE?
Association with mast cells (mast cell degranulation) --> allergies; parasite infection
36
What are the characteristics of IgD?
Occurs on surfaces of naive B cells; very little in serum
37
What is affinity maturation?
Occurs only for B cells; with the help of T cells, B cells can enter germinal centres in secondary lymphoid tissue after encountering the antigen --> rapid division: 1. Somatic hypermutation: mutation of immunoglobulin variable region, requires activation induced cytidine deaminase (AID) 2. Selection: for higher affinity 3. Possible class switch
38
Which two types of cells leave the germinal centres?
Quiescent circulating memory B cells; affinity maturated possibly class switched
39
What are chimeric antibodies?
Mouse variable region + human constant regions (-ximab)
40
What are humanised antibodies?
Only parts of the variable region that come in contact with the antigen are from the mouse (-zumab)
41
What type of ending do human monoclonal antibodies have?
-umab; adalimumab --> against TNFalpha
42
What are the differences between MHC I and II
MHC I: monomer, associated with beta2 microglobulin, endogenously expressed on all nucleated cells, binds to 8-10 aa, important in viral infections and tumors, endogenous proteins MHC II: heterodimer (alphabeta), expressed on specialised antigen presenting cells, binds to 10-15 aa, exogenous proteins
43
Where are the genes coding for MHC I and II situated?
Chromosome 6; 3 different HLA coding for MHC I and 3 for MHC II; polygenic and polymorphic
44
How does T cell activation occur?
Signal 1: TCR and MHC complex (CD4 with MHC II and CD8 with MHC I) Signal 2: co-stimulation (CD80/86 with CD28) Signal 3: APC secretes cytokines to direct differentiation of CD4 T cells Activation --> division and production of cytokines
45
Which types do CD4 T cells differentiate in and which cytokines are produced?
Th1: IL2, IFN-gamma, response to intracellular pathogens (TB, listeria, leprosy) and viruses, macrophages and CD8 T cells Th2: IL4, IL13, responses to extracellular parasites (schistosomes), promote B cell maturity Th17: IL17,21,22, important in the gut (parasites), extracellular bacteria and fungi, help epithelium and fibroblast, neutrophil chemotaxis Treg: TGFbeta and IL10, adaptive and innate immune response control
46
Which cytokines help naive T cell differentiation?
IL6,12 and TNFalpha
47
How does thymic education work?
1. Obtain functional TCR 2. Positive selection for self MHC (cortex) with specialised APC: select CD4 or CD8 3. Negative selection to eliminate high affinity self-reactive T cells: thymic medullary epithelial cells (TMECs) express tissue specific antigens (TSAs)
48
Which are the TSAs represented by the liver, pancreas, islets of langerhans, eye, thyroid?
``` Live: serum amyloid P Pancreas: trypsin Islets of langerhans: insulin Eye: cristallin Thyroid: thyroglobulin ```
49
Which are the peripheral mechanisms of immune tolerance?
Anergy: T cell remains in circulation but is unresponsive to future stimulation (signal 1 but not 2) Rregulatory T cells: decrease proliferation, cytokine production, reduce co-stimulation, alter cytokine production
50
What are the two types of regulatory T cells?
nTreg: produced in thymus, respond to self antigens, important for autoimmunity aTreg: develop in periphery, constant low level exposure of antigen, regulation for responses to food antigens
51
What is IPEX?
Multiple autoimmune diseases developed by individuals lacking nTregs
52
How and where does activation of naive lymphocytes occur?
Dendritic cells move to lymph nodes: secrete cytokines and chemokine —> up regulation of adhesion molecules of endothelial venules —> increase in migration of naive T cells into the lymph node
53
Which types of cells play a role in immunological memory?
Plasma cells: live for year, high affinity antibodies, protective immunity B cells: high frequency, can develop into plasma cells Memory t cells: higher frequency before primary infection, immediate effector function
54
What is inflammation?
The reaction of vascularised living tissue to local injury
55
What are the four signs of inflammation?
Redness; swelling; heat; pain
56
Which are the vascular changes in acute inflammation?
1. Transient vasoconstriction of arterioles 2. Vasodilation and increased blood flow 3. Slow of the circulation because of increased permeability of the microvasculature (stasis) 4. Exudation of plasma proteins and fluid (oedema)
57
What are the differences between exudates and transudates?
Exudates: inflammatory extravascular fluid that has a high protein concentration, much cellular debris and SG above 1020 Transudates: ultrafiltrates of low protein content
58
What is pus?
A purulent exudate rich in leukocytes (mostly neutrophils) and parenchymal cell debris
59
How does margination occur?
Inflammation --> histamine (C5a or LPS) and thrombosis factors --> weibel-palade bodies within endothelium release cell adhesion molecules (P and E selectin) --> neutrophils slow down and roll on the endothelium
60
What happens to neutrophils after margination?
1. Release of IL8 attracts neutrophils along concentration gradient 2. Chemotaxis in response to: bacterial products, complement components (C5a), products of lipooxygenase pathway of arachidonic acid metabolism (leukotriene B4) 3. Diapedesis and extravasation: interaction btw integrin molecules on leukocytes and ICAM-1 on endothelium
61
What are the differences between acute suppurative, fibrous and membranous inflammation?
Suppurative: presence of puss (accumulation of neutrophils), appendicitis Fibrous: fibrin + neutrophils (lobal pneumonia) Membranous: inflammatory membrane forms over inflamed tissue (diphteria, pseudomembranous colitis)
62
What is the histology of chronic inflammation?
1. Infiltration by mononuclear cells: macrophages, lymphocytes and plasma cells 2. Proliferation of fibroblasts and small blood vessels
63
What are granulomas?
``` Formed from macrophages due to chemokine release; Early granuloma (macrophages + lymphocytes): 1. non-caseating epitheloid granuloma (+ fibroblasts producing collagen) 2. caseating epitheloid granuloma (+ fibroblasts producing collagen) ```
64
What are some examples of granulomas?
1. Foreign body granuloma 2. Pulmonary tubercolosis: granulomatous inflammation 3. Paraffin oil
65
What is atopy?
Inherited tendency to make immediate hypersensitivity responses due to mast cell degranulation and histamine release (wheal and flare)
66
What are common therapies for immediate hypersensitivities/allergies?
anti-histamines, beta2-adrenorecepetor agonists, corticosteroids
67
How does an allergic reaction work?
Allergen activates CD4 cells --> Th2 --> IL-4,5,13 release --> B cell differentiation into plasma cells that produce IgE
68
What is the most common autoimmune disease?
Graves' thyroiditis
69
What are examples of organ specific and non-organ specific autoimmune disease?
Organ-specific: Type I diabetes, graves' thyroiditis | Non-organ specific: systemic lupus erythematosus, rheumatoid arthritis
70
What are serum autoantibodies?
Example of breakage of self tolerance; usually IgG class
71
What is myasthenia gravis?
Autoimmune disease: antibody to the ACh receptor --> muscular weakness and fatigue
72
How is diabetes T cell mediated?
1. CD8 T cells kill beta cells 2. CD4 T cells mediate inflammation 3. Failure of Treg to suppress
73
What are the differences between primary and secondary immunodeficiencies?
Primary: inherited defect, rare Secondary: acquired defect, common
74
What is Di George syndrome?
No T cells --> often abnormalities of heart and facial features
75
What is SCID?
Severe combined immune deficiency: no B and T cells
76
What is chronic granulomatous disease?
Neutrophils can't kill bacteria
77
What is hypergammaglobulinemia?
Absence of CD40 ligand on T cells (important for communication with B cells) --> you can only make IgM
78
What is HAART?
Highly active antiretroviral therapy; used for AIDS against HIV
79
What are examples of iatrogenic immune deficiency?
Anti-TNFalpha for rheumatoid arthritis --> mycobacterial infections Anti-IL17 for psoriasis --> fungal infections
80
How do cancers hide from immune attack?
Cancer cell: expresses PD-L1 which interacts with programmed death (PD) receptors on effector cells --> stops killing of cancer cell
81
How are organisms that cause infectious diseases grouped?
``` Parasites: helminths and protozoa Fungi Bacteria Viruses Prions ```
82
Which organisms are microparasites and which are macro?
Macro: helminths Micro: protozoa, bacteria, fungi, viruses
83
What are the most serious helminth infections?
Multicellular | Tapeworms (taenia solium) and flukes (schistosoma mansoni)
84
What are characteristics of protozoa and what are some examples?
Single cell organisms; active growth stage (trophozoite) and dormant stage (cyst); malaria, toxoplasmosis, leishmaniasis
85
What are characteristics of fungi?
Grow as single cell (yeast), branched filaments (hyphae --> form mycelium) or both (dimorphic fungi); thick cell wall composed of chitin
86
What is peptidoglycan?
Also known as mucopeptide or murein; polymer of hexose sugars NAG and NAM and aa (tetrapeptide chain)
87
Which bacteria cannot be seen with Gram stain?
Acid fast bacteria (outer membrane of free mycolic acids and polypeptides); mycobacterium tubercolosis
88
What is the structure of capsules?
Gelatinous layer outside cell wall, primarily composed of polysaccharides; antiphagocytic
89
What are the functions of pili?
Attachment and conjugation
90
What are spores?
Only produces by some gram+ bacteria (bacillus and clostridium species); keratin-like coat confers resistance to heat, chemicals and drying
91
What is the structure of viruses?
DNA or RNA; capsid core; polymerase protein; envelope (sometimes)
92
What are capsids?
Constructed from small number of virally-encoded protein subunits (capsomeres) 3 types of symmetry: icosahedral, helical, complex
93
Which viruses have a complex capsid?
Poxviruses
94
What are the differences between resident and transient flora?
Resident: re-establishes itself, not removed by routine hand wash, not associated with transmission of infection, most common is Staph. epidermidis Transient: doesn't re-establish itself, removed by routine hand wash, associated with transmission of infection, most common is Staph. aureus
95
What are opportunistic infections?
Caused by non-pathogenic microorganisms that act as pathogens in certain circumstances
96
What is immunopathogenesis?
Primary cause of cell death in many infections, caused by killing of infected cells by the host immune system
97
What is the difference between symptom, sign and syndrome?
Symptom: subjective features of disease experienced only by the patient Sign: objective manifestations of disease that can be observed and measure by others Syndrome: group of symptoms and signs of a disease
98
What are the obligatory steps for infectious organisms?
1. Entry and spread 2. Evasion 3. Multiplication 4. Transmission
99
What are the stages of infectious disease progression?
1. Incubation 2. Prodrome 3. Illness 4. Recovery/convalescence
100
What is the difference between sporadic, endemic, epidemic, pandemic?
Sporadic: occasional Endemic: continuously present in the population Epidemic: increase in numbers in an area in a short period of time Pandemic: epidemic disease that has world-wide distribution
101
What is the difference between superficial and systemic infection?
Superficial: self limiting, replication in epithelium at site of entry and damage is local Systemic: replication at multiple sites due to infection of deeper tissues, spread through lymph and blood
102
What are nosocomial infections?
any infection acquired in a hospital or medical facility. Can affect patients and health care workers and are common because: easily moved around by staff, patients or visitors, not always can be prevented by proper hand washing. Most common in hospitals: Staph. aureus, c-difficile...
103
What are some examples of antibiotic-resistant bacteria?
Methicillin resistant S. aureus (MRSA), VRE and CPE
104
Which are the determinants of pathogenesis?
Opportunism, attachment, invasiveness, virulence, cellular pathogenesis
105
What does tissue tropism mean?
Different tissues within the host that are infected by the pathogen
106
What is a permissive cell?
One that allows the pathogen to replicate
107
How do bacteria spread to deeper tissues?
Produce specific enzymes (invasins): 1. Collagenase and hyaluronidase 2. Coagulase: fibrin clot around bacteria to protect from phagocytosis 3. Leukocidins 4. Hemolysins
108
What is virulence?
Degree of pathogenicity of a microorganism | Pathogenicity: ability of a microbe to cause disease
109
How is virulence measured?
LD50 and ID50
110
What are the differences between endo and exotoxins?
Endotoxins: from gram negative bacteria, LPS, genes contained in bacterial chromosome, low toxicity Exotoxins: gram+ and - bacteria, secreted, genes in plasmid or phage, high toxicity, high antigenicity
111
What are superantigens?
Toxins that stimulate the immune system; can bind to MHC II molecules non-specifically and stimulate a large number of T cells
112
What is epidemiology?
Science that studies where and when diseases occur and how they are transmitted in a population
113
What factors affect the spread of infection?
Reservoirs and modes of transmission
114
What are emerging diseases?
Unrecognised disease, or previously recognised infection that has expanded into a new ecological niche, often accompanied by a significant change in pathogenicity
115
What are zoonotic diseases?
Spread between animals and people
116
What are the types of vehicle transmission?
Waterborne, airborne, foodborne
117
What are the types of vector transmission?
Mechanical and biological
118
What is the difference between vertical and horizontal transmission?
Vertical: between mother and child Horizontal: person-to-person that is not mother to offspring
119
What are the two main laboratory methods to confirm infection?
Direct detection: culture, microscopy and molecular methods | Indirect detection: presence of antibodies against the pathogen
120
What are the two methods of detection of nucleic acids?
Hybridisation techniques with nucleic acid probes; PCR
121
What is meant by titre?
Refers to antibody concentration in a sample and is associated with the number of times you can dilute a sample and still detect antibodies; retrospective
122
Is it easier for RNA or DNA viruses to develop resistance?
RNA viruses: presence of error-prone polymerase enzyme

FBS2 (3 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions