Immunology exam 1 Flashcards

Question

Primary Lymphoid Follicle

Answer 1

Ares within lymph nodes that consists principally of B cells enmeshed in a network of specialized stromal cells called follcular dendritic cells.

Answer 2

Made by several cell types in secondary lymphoid organs and is bound by the BAFF receptor expressed by B cells. It promotes B cell survival

Answer 3

Maturation first involves the alternative splicing of the heavy chain mRNA so that the cell makes IgD as well as IgM. This is followed by a shift from an excess of IgM over IgD on the cell surface to an excess of IgD over IgM

Answer 4

Similar to primary lymphoid follicle except with a germinal center. At the germinal center, the activated B cells become large proliferating lymphoblasts called centroblasts; these mature into more slowly dividing B cells called centrocytes, which have undergone isotype switching and somatic hypermutation.

Answer 5

located within secondary lymphoid follicle. It is where affinity maturation occurs. Also the resting location for memory B cells.

Answer 6

Plasma proteins constitutively produced by the liver and are present in the blood, lymph, and extracellular fluid

Answer 7

An alternative C3 convertase which works right at the surface of the pathogen. A larger proportion of the C3b fragment it produces become fixed to the pathogen.

Answer 8

Soluble C3 convertase. C3 spontaneously hydrolyzes which activates C3 to bind factor B. Cleavage of B by the serine protease factor D produces the soluble C3 convertase which then activates C3 molecules by cleavage.

Answer 9

Increases the speed and power of complement activation by binding to the C3 convertase C3bBb on microbrial surfaces and preventing its degradation

Answer 10

Complement control protein that binds to C3b and facilitates its further cleavage to a form called iC3b by the plasma serine protease factor I.Fragment iC3b cannot assemble a C3 convertase

Answer 11

Both are complement control proteins located at the membrane of human cells that binds to C3b component of the alternative C3 convertase, cause its dissociation and inactivation. MCP can also make C3b susceptible to cleavage and inactivation by factor I

Answer 12

Receptor on macrophage that binds to C3b fragments on pathogens that make phagocytosis more efficient. It also protects the surface of the cells its expressed on by making them susceptible to Factor I

Answer 13

Coating of pathogen with protein that facilitates phagocytosis

Answer 14

Prevent the recruitment of C9 by the complex C5b, C6, C7 and C8

Answer 15

They increase inflammation at the site of complement activation through binding to receptors on several cell types. They can induce anaphylactic shock, which is an acute inflammatory response that occurs simultaneously in tissues throughout the body so they are referred anaphylatoxins.

Answer 16

A glycoprotein is a protease inhibitor present in human secretions and plasma. It lures a protease with a bait region that is allowed to cleave. This activates alpha2- macroglobulin to covalently attach to the protease via its thiosester and it also undergoes a conformational change by which it envelops the protease. (Defense mechanism against protease prodcued by pathogens)

Answer 17

Human antimicrobial peptides that are rich in positively charged arginine residues and which characteristically have three intra-chain bonds. There are two classes: alpha and beta defensins. They are synthesize as part of longer, inactive polypeptides that are then cleaved to release the active fragment.

Answer 18

Are expressed mainly by neutrophils, the predominant phagocytes of innate immunity and by Paneth cells

Answer 19

Are expressed by a broad range of epithelial cells, in particular those of the skin, the respiratory tract and the urogenital tract.

Answer 20

Receptors and plasma proteins that recognize carbohydrates. These can be present on macrophages that will aid in phagocytosis of pathogen

Answer 21

A phagocytic receptor of macrophages that is not a lectin; it binds to an assortment of ligands that share the property of being negatively charged.

Answer 22

A process of engulfment initiated by the binding of these macrophage receptors to their microbial ligands in which the receptor bound pathogen is surrounded by the macrophage membrane and internalized into endosome or phagosome.

Answer 23

Is formed when phagosomes fuses with lysosomes which are loaded with degradative substances that destroy pathogens

Answer 24

Small proteins that are made by a cell in response to an external stimulus and influence other cells by binding to a specific receptor on their surfaces. Can be produced by macrophages when it receives signal by toll-like receptors that pathogen is present which will recruit other immune system cells.

Answer 25

A family of signaling receptors, each of which is specific for a different set of microbial products.

Answer 26

Expressed by macrophages and has specificity for LPS and related compounds present on the outside of gram-negative bacteria. In present of infection it can activate the expression of cytokine genes that can induce innate immune responses. Cytokines that induce inflammation are known as inflammatory cytokines. TLR4 is a homodimers of a single polypeptide

Answer 27

TLRs that sense proteins, carbohydrates, and lipids characteristics of microbial cell surface, are located on the surfaces of human cells. TLRs that detect nucleic acids of pathogens reside in the membranes of endosome within cytoplasm.

Answer 28

LPS is detected by the complex of TLR4, CD14 and MD2. The activated receptor binds the adaptor protein MyD88 which binds protein kinase IRAK4. IRAK4 will phosphorylate itself and dissociates from the complex and phosphorylates another adaptor protein TRAF6 which will eventually lead to the activation of a kinase complex called the inhibitor of kB kinase (IKK). IKK phosphorylaes IkB , causing its dissociation from the comples NFkB. NFkB can now move into the nucleus where it directs the activation of cytokine gene and other adhesion molecules that will intensity macrophage's effector function

Answer 29

After TLR3 or TLR4 have detected their ligands, they will form a complex with adaptor proteins TRIF and TRAM. This will phosphorylate TRAF3 and create a kinase cascade. Phosphorylation of IRF3 in the cytoplasm will allow it o enter the nucleus where it directs the transcription of the genes for type I interfererons and cytokines

Answer 30

Cytokine that causes fever and induces acute- phase protein production by hepatocytes

Answer 31

Activates vascular endothelium and increase vascular permeability, which leads to increase entry of complement and cells to tissue and increased fluid drainage to lymph nodes. It also cause fever mobilization of metabolities and shock

Answer 32

Activates vascular endothelium, activates lymphotes, local tissue descrution, increase access of effector cells. It also causes fever and production of IL6

Answer 33

A chemokine (Chemoattract cytokine) that recruits neutrophils and basophils to site of infection

Answer 34

Activates NK cells

Answer 35

Messengers that direct flow of leukocyte traffic . Two major families are defined on the basis of pairs of cysteine residues, which are either adjacent (CC) or separatedby another amino acid (CXC)

Answer 36

Chemokine receptors on neutrophiles that bind CXCL8 coming from infected tissue.

Answer 37

1) The leukocyte's adhesive properties are altered so that it can leave the blood and enter the tissue 2) the leuckocytes movement is guided toward the center of infection along a gradient of the chemokine.

Answer 38

Lymphocytes that specialize in defense against viral infections

Answer 39

Short lived granulocyte that have phaogcytic activity. They are the most abundant WBC and are excluded from healthy tissue and leave the blood in response to inflammatory mediators released by infected sites.

Answer 40

1) selectins - carbohydrate binding proteins which have specificity for the oligosaccharide of different vascular addressins 2) Vascular addressins 3) Integrins- binds to proteins 4) Immunoglobulin superfamily

Answer 41

The process by which neutrophils migrate out of blood capillaries and into tissues

Answer 42

Phagosomes containing pathogens fuse with azurophilic ( primary) granules and specific (secondary) granules. Primary granules contians proteins and peptides that can disrupt and digest microbes. The specific granules contains lactoferrin that compete with pathogens for iron and copper. They also contain NADPH oxidase, an essential enzyme for neutrophil function that is assembled in the phagosome after fusion of the phagosome with the azurophilic and specific granules.

Answer 43

Produces a superoxide radical that are converted into hydrogen peroxide. It raises the pH and activates the antimicrobial peptides and proteins and attacked trapped pathogens in phagosomes.

Answer 44

1) Bacteria is phagocytosed 2) phagosome fuse with primary and secondary granules 3) pH of phagosome rises, antimicrobial response is activates and pathogen is killed 4) pH of phagosome decreases,fuses with lysosome which allows acid hydrolases to degrade pathogen completely 5) neutrophil dies and is eaten by macrophage

Answer 45

Molecules that induce fever

Answer 46

A systemic effect of IL1, IL6 and TNF-alpha that changes the spectrum of soluble plasma proteins secreted by hepatocytes in the liver

Answer 47

Proteins whose synthesis and secretion is increased during the acute - phase response. Two acute phase protein called mannose- binding lectin and C-reactive protein enhance fixation of complement at pathogen surfaces

Answer 48

A calcium dependent lectin that binds to mannose-containing carbohydrates of bacteria, fungi, protozoans and virues. It circulates in plasma as a complex with two serine protease zymogens: MBL-associated serine protease (MASP) 1 and 2. Two molecules each of MASP-1 and MASP-2 is associated with MBL. When MBL binds to pathogen, one molecule of MASP-2 is induced to become enzymatically active and cuts itself. It then cuts the second MASP-2 molecule. Substrates for the activated MASP-2 protease are the C4 and C2 complement components. C4 is similar to C3 and C2 is similar to factor B.

Answer 49

C4 molecule interacts with MASP-2 and is cleaved into C4b and C4a fragments. C4b is fixated to pathogen surface. When a C2 molecule interacts with MASP-2, it is cleaved into a larger C2a and a smaller C2b. Larger C2a binds to a pathogen bonded C4b. The complex of C4b and C2a known as C4bC2a is a C3 convertase. It is a component of both the classical and lectin pathway. The classical convertase binds and cleaves C3 to yield C3b which attaches to pathogen surface. This in turn activates factor B to assemble molecules of the alternative C3 convertase, C3bBb

Answer 50

It contains 5 identical subunits that form a pentamer. When CRP binds to phosphocholine components of LPS on pathogen surfcae, it can also interact with C1, the first component of the classical pathway of complement activation. C1 has similar structure to MBL but instead of MASP 1 and 2, it has C1r and C1s. CRP binds to C1 stalk and causes one molecule of C1r to cut intself, the other molecule of C1r and both molecules of C1s. Now C1s becomes an active proteases that cleaves C4 , leading to formation of C4bC2a

Answer 51

Cytokines made when human cells becomes infected by a virus. It interferes with viral replications of infected cells, and signals nearby uninfected cells that they too should prepare to resist a viral infection.

Answer 52

Type 1 interferon production is induced by intracellular events that follow viral infection or the triggering of TLR3. Infection or ligand sensing triggers the phosphorylation of the transcription factor IRF3 in the cytoplasm which dimerizes and enters the nucleus to help initiate transcription of the Interferon-beta (IFN-b) gene which also requires the transcription factors NFkB and AP-1

Answer 53

When interferon binds to its receptor, the intracellular Jak1 and Tyk2 kinases associated with the receptor , it initiates reactions that changes the expression of different genes.

Answer 54

1) induce resistance to viral replication in all cells 2) Increase expression of ligands for receptors on NK cells 3) activate NK cells to kill virus infected cells

Answer 55

These cells secrete up to 1000x more interferon than other cells

Answer 56

Stimulation of NK cells with type 1 interferons favors the development of the cell's killer function. Stimulation with IL-12 favors the production of cytokines. One of the main cytokines is IFN-gamma (aka Type 2 interferon). Its function is to activate macrophages that will produce more IL-12 so it is positive feedback. Macrophages can activate T cells thus activating the adaptive immune response.

Answer 57

Most NK cell recepotrs have extracellular ligand-binding regions that are made up immunoglobulin domains or lecti-like domains. There an inhibitory and activating type of both receptors. Activating receptors have short cytoplasmic tails and charged amino acid residues in the transmembrane domain that facilitates interaction with intracellular signaling proteins. Inhbitory receptors have long cytoplasmic tails that caontain a short amino acid sequence motif called immunoreceptor tyrosine based inhibitory motif (ITIM), which binds protein phosphatases that act to inhibit the activating pathway

Answer 58

NKG2D is a lectin like receptor that binds to ligands called MIC-A and MIC-B, cell surface proteins that produced in response to stress. Healthy cells resists attack by NK cells because signals generated from inhibitory receptors dominate those generated from activating receptors. NK cells attack the virus -infected cell because the signal generated by NKG2D interacting with MIC proteins tips the balance to activation.

Answer 59

The process by which pathogens select particular lymphocytes for expansion

Answer 60

The proliferation of selected clones

Answer 61

A type of phagocytic cell leukocyte that reside in tissues and are specilized in the uptake and breakdown of infection agents. The presence of infection causes dendritic cells to differentiate into mobile cells that transport bacteria and their antigens through the lymph to the secondary lymphoid tissues.

Answer 62

Binds CD8 T-cells and processes intracellular antigens.It is expressed on all cells

Answer 63

Binds CD4 T cells and processes extracellular antigens. It is only expressed on professional APCs ( DC, macrophages, B cells)

Answer 64

a single motif of about 100-110 amino acids long and folds up into a compact and exceptionally stable protein.

Answer 65

Heavy chain- constant IgG, IgD, IgA have 3 constant domains IgM, IgE have 4 contant domains Light chain: All have 1 constant domain Only 1 variable domain for both heavy and light chian

Answer 66

1) Light and heavy chain each have 3 hypervariable regions (CDRs) so they are totaly of 6 CDR 2) CDR are flanked between less variable framework region 3) Made of 4 polypeptides

Answer 67

Highly repetitive sequences that flank the 5' side of each C gene, with the exception of gamma gene, that mediate recombination

Answer 68

Occurs after gene rearrangement. It randomly introduces point mutations at a high rate throughout the V region.

Answer 69

Enzyme that is made in proliferating B cells. AID converts cytosine in single stranded DNA to uracil. During transcription, when the two DNA strands become temp separated, AID converts cytosine into uracil. Other enzymes then act to convert the uracil to any of the 4 normal DNA bases

Answer 70

CD3 proteins and squiggly line chian remain in stable association with the T cell receptor. In this complex, CD3 proteins and sqiggly chain transmits singals to the cells interior after antigen has been recognized by the alpha and beta chain of the TCR . The alpha and beta chain has short tail that cannot signal.

Answer 71

A calcium dependent lectin that retains MHC class I heavy chains ( alpha) in the ER till beta2- microglobulin binds

Answer 72

ERp57 and tapasin - bridging proteins that bind to both mhc clas I and the TAP-1 subunit of the peptide transporter Protein disulfide isomerase ( PD-1) - stabalizes the disulfide bond of the alpha2 domain of the class I heavy chain Calreticulin- resembles soluble calnexin and has similar chaperone function

Answer 73

An enzyme that removes amino acids from the amino terminal end of the peptide on MHC 1 to improve fit

Answer 74

A protein embedded in the ER membrane that transports peptides across the ER membrane

Answer 75

Associates with alpha and beta chain of MHC 2 to prevent it from bindin peptides present in the ER. It also delivers the MHC 2 to endocytic vesicles where they bind peptides. The vesicles called MHC class II contain proteases that selectively cleave the invariant chain which will leave a small fragment covering the peptide binding site called Class II associated invariant chain peptide (CLIP)

Answer 76

Removes CLIP and helps the binding of peptide to mhc II. When HLA-DM binds to mhc II it causes CLIP or weakly bound peptides to be released

Answer 77

It allows extracellular antigens to be presented by MHC I. Two possible ways 1. Phagocytosis of dead, infected cells by APC allows complexes of MHC I and viral peptides to be transported from the dead cell to the membranes of intracellular vesicles inside the APC to the cell surface 2) extracellular viral proteins are deliver by endocytic vesicles to proteasome degradation and presented by the usual mhc I pathway

Answer 78

Soluble proteins that inhibit C5b, C6 and C7 binding to cell membrane

Answer 79

Membrane bound form of antigen receptor of B cells

Immunology exam 1 Flashcards

(103 cards)