Quiz 3

Question 1

Which MHC class molecule is bound by CD4+ versus CD8+ presenting cells?

Answer 1

Class II is bound by CD4+

Class I bound by CD8+

Question 2

Which genes are expressed in MHC class II molecules versus MHC class I?

Answer 2

DP, DQ, DR - class II
A, B, C (has beta 2 microglobulin)- Class I

Question 3

Which cells present class II MHC genes versus class I?

Answer 3

Profession antigen presenting cells - class II
All nucleated cells - class I

Question 4

What cytokine up-regulates type I MHC?

Answer 4

IFN-alpha, IFN-Beta

Question 5

What are the two types of cells called when associated with class II versus class I to their respective T-cells>?

Answer 5

Class II - antigen presenting cell (CD4 helper)

Class I - target cell (CD8+ cytotoxic)

Question 6

What is the endogenous pathway?

Answer 6

Takes antigens from cytosol, degraded in the proteosome and trasported via TAP to become class I

Question 7

What is the exogenous pathway?

Answer 7

Takes antigens from the extracellular milieu, MHC II associate with invariant chain, CLIP, presented on plasma membrane

Question 8

What is the process of T cell development?

Answer 8

Hematopoiesis -> pro T cell (thymus) -> double neg (pre T)–> double positive (immature T cell) –> Single positive stage (mature Th/Tc cell) –> Naive T cell enters circulation

Question 9

What are the two signals that t cells need for activation?

Answer 9

TCR engagement (TCR:antigen+Self-MHC and a costimulatory signal (CD28:B7 APC)
-those only getting one signal is anergized

Question 10

What does IL-2R bind and do?

Answer 10

IL-2R is a trimeric receptor needed for IL-2 binding and signaling at cytokine levels (T cell proliferation)
alpha - low affinity
beta/gamma -0 intermediate affinity
alpha/beta/gamma - high affinity

Question 11

What is the difference between effector and naive t cell rolling?

Answer 11

Naive T cell rolling/diadepsis by sialy-Lewis (l-selectin), effector T cells through E/P-selectin

Question 12

How is the t cell immune response down regulated?

Answer 12

Stop synthesis of IL-2/IL-2R and increased expression of TGF-Beta

Question 13

What does Th1 secrete?

Answer 13

Makes IL-2, IFN-gamma, - USEFUL FOR CELL MEDIATED IMMUNITY

Induced by IL-12, IFN-gamma

Question 14

What is Th1 particularly effective against?

Answer 14

Viruses, intracellular bacteria, malignant cells, fungi, extracellular bacteria

Question 15

What does Th2 make?

Answer 15

IL-4, IL-5 - USEFUL FOR HUMERAL IMMUNITY

Induced by IL-4, IL-10

Question 16

What is Th2 effective against?

Answer 16

Extracellar bacteria, helmithic parasites, extracellular viruses, allergic disease

Question 17

What do Treg cells make?

Answer 17

TGF-beta, IL-10 for downregulation of immune response

Induced by TGF-beta, and low IL-6, IL-23

Question 18

What does Th1 promote versus Th2?

Answer 18

Th1 - activates macrophages, NK cell, and increased cytotoxic activity
Th2 - b cell activation and antibody production, and isotype switching

Question 19

What is the difference between memory and naive CD4 t cells?

Answer 19

CD45RO - memory

CD45A - naive

Question 20

what are other mechanisms of CD4 t cell activation?

Answer 20

Mitogens - non-specifically activate T cell or B cell
Superantigens - trigger TCR but are NOT processed, capable of bind directly to MHC class II to activate a significant number of T cells

Question 21

What is the role of Th17 cells?

Answer 21

They are proinflammatory cells, induce neutrophil recruitment, produce IL-17, IL-6, induced by IL-23, IL-6, TGF-Beta, and lack of other cytokines until Th1/Th2 are upregulated

Question 22

Which antigens stimulate B cells directly in absence of T cell help?

Answer 22

LPS, and polysaccharides with repeating identical determinants
-Produces IgM»>Ig anything else

Question 23

Which helper cell aids in B-cell proliferation and how does it do it?

Answer 23

BCR binds antigen, Th2 cells deliver 2nd signal via CD40L and cytokines

Question 24

What co-stimulatory signals are required for B-cell activation?

Answer 24

CD28 on T cells & B7 Complex (CD80/CD86) on Bcells

CD40L on T cells and CD40 on B cells

Question 25

What is hyper-IgM syndrome?

Answer 25

Absence of functional CD40L

Question 26

Which cytokine is responsible for switching to IgE

Answer 26

IL-4

Question 27

Which cytokine is responsible for switching b cell to IgA

Answer 27

IL-10, TFG-beta

Question 28

What is the role of follicular dendritic cells?

Answer 28

Trap antigen and lymphocytes, antigen presented on surface of FDC to b cells

Question 29

Which cells play an important role in controlling viral infections?

Answer 29

Cytotoxic CD8+ cells that can directly kill virally infected cells and making cytokines such as IFN-gamma that inhibit vial reproduction

Question 30

What is the big difference between apoptosis and necrosis?

Answer 30

Apoptosis - suicide, cell shrinkage and plasma membrane integrity is preserved Necrosis - murder, loss of membrane integrity and cellular swelling

Question 31

What is the Ca++ dependent mechanism of killing target cells?

Answer 31

Release of granules from CD8+ cells including perforin, and granzymes

Question 32

What is the Ca++ independent mechanism of killing target cells?

Answer 32

Expression on the surface of the CD8+ cell of cytokines (IFN-gamma, INF alpha and beta) that signal apoptosis such as FasL

Question 33

What is the CD4+ independent mechanism in which naive CD8+ cells differentiate into effector cytotoxic CD8+ cells?

Answer 33

Dendritic antigent presenting cells through MHC class I/antigen complex and costimulated through CD28 receptor

Question 34

What is the CD4+ dependent mechanism in which naive CD8+ cells differentiate into effector cytotoxic CD8+ cells?

Answer 34

CD4+ upregulate B7-1 and produce IL-2

Question 35

What are the requirements for effector CD8+ cytotoxcity?

Answer 35

Adhesion between effector and target cells (LFA-1 w ICAM-I) or CD2 w LFA3, and TCR activation by MHC class I/Ag

Question 36

What are the effector functions of NK cells?

Answer 36

``` Cytotoxicity (mediated by perforin/granzymes and FasL) Cytokine production (IFN gamma, TNF alpha, IL12) ```

Question 37

What do NK cells target and how do they kill their target cells?

Answer 37

Viruses, killing by release of granules that contain perforin and granzymes. Also express Fas: that will kill cells with Fas receptor

Question 38

How do NK cells recognize their targets?

Answer 38

They target cells that lack HLA class 1 expression

Question 39

How do NK cells kill cells coated with antibodies?

Answer 39

NK cells express Fc-gamma-RIII or CD16 that binds IgG1, IgG3 and kill via antibody dependent cell mediated cytotoxicity

Question 40

What are the two types of NK activator and inhibitor receptors?

Answer 40

C-type lectin family receptors (CD94, NKG2) | Killer cell immunoglobulin-like receptors (KIRs)

Question 41

How is infection blocked from being deposited and absorbed?

Answer 41

Secretory IgA, mucociliary apparatus, nonspecific mucoproteins

Question 42

How is infection propagated?

Answer 42

Virus replicates within the host cell, leading to cell death via apoptosis, infections viral particles are released for hours after cell death

Question 43

What is normal, fever, and high fever?

Answer 43

Normal - 98.6 F = 37 C Fever - 100.5 F = 38 C High fever - 104 F = 40 C

Question 44

What exogenous and endogenous factors are released during fever?

Answer 44

Exogenous - PAMPS, bacterial SA, LPS | Endogenous - DAMPS, IL-1TNF, IFN

Question 45

Which cytokine is responsible for inhibition?

Answer 45

IL-10, inhibits cytokine production, inhibits inhibition of apoptosis of neutrophils

Question 46

What is the immune system function?

Answer 46

Resist pathogens, microbes that cause diease, foreign bodies and abnormal cells. Resistance to pathogens is primary

Question 47

What makes a bacteria gram positive?

Answer 47

Thick peptidoglycan layer

Question 48

How does extracellular bacteria cause pathology?

Answer 48

Inflammation, or producing toxins

Question 49

How does intracellular bacteria cause pathology?

Answer 49

Causing chronic infections which activate and sustain immune response against host tissue

Question 50

What is unique about parasites?

Answer 50

Unicellular and multicellular eukaryotic organisms that account for more morbidity and mortality

Question 51

What are the exterior defenses?

Answer 51

Skin, mucosal epithelium, lysozyme in secretions, acidic environment of the stomach

Question 52

What are interior defenses?

Answer 52

Causes inflammation, neutrophils, macrophages, innate defense mechanisms are presents prior to exposure to infectious agents

Question 53

What are the receptors of innate immunity?

Answer 53

Pattern recognition molecules, toll-like receptors

Question 54

What is the general immunity for extracellular bacteria?

Answer 54

opsonizing antibody IgG enhances phagocytosis, C3b, neutralizing antibody, complement activation

Question 55

What is the general mechanism for intracellular bacteria?

Answer 55

CD4+ T cell to Th1 secreting IFN-gamma to activate macrophages, CD8+ T cell into cytotoxic T cells

Question 56

What is the evasion strategies for bacteria?

Answer 56

Exotoxins, IgA protease, capsules, prevention of phagosome0lysosome fusion, escape from the phagosome

Question 57

What is the mechanism immunity to viruses?

Answer 57

Inhibit IFN alpha and beta, NK cell lysis, neutralizing antibodies IgG, IgA, complement, cell mediated

Question 58

What are virus evasion strategies?

Answer 58

Down regulation of MHC class I proteins (attacked by NK cells), Virokines (EBV) and viroreceptors (IL-10)

Question 59

What is the mechanism for immunity to parasites?

Answer 59

Macrophages, Th1 responses are most important, activation of Th2 results in IgE, activation of eosinophils

Question 60

What is the evasion strategies of parasites?

Answer 60

Cuticle formation, antigenic variation