11/6/12

Question 1

function of mhc molecules

Answer 1

present peptides for recognition by TCR

Question 2

mhc I get peptides from where and how?

Answer 2

intracellular Ag that are digested by protease

peptide transported to ER and loaded onto MHC as it is synthesized/secreted to plasma membrane

Question 3

mhc II gets peptides from where and how?

Answer 3

protein phagocytosed, degraded into peptides in phagolysosome.

mhc II syn in golgi buds off and fuses with phagolysosome where mhc II binds peptide

transported to plasma membrane

Question 4

what expresses mhc I

Answer 4

almost all cells except RBC

less-so on neurons

Question 5

what expresses mhc II

Answer 5

APC

B cells, macrophages, DC, thymic epithelium

Question 6

implications of mhc I?

Answer 6

problem in cells

i.e. APC infected. Get rid of cell.

Question 7

implications of mhc II?

Answer 7

problem outside cells

i.e. APC has detected an infection. Don’t necessarily get rid of cell

Question 8

What do t cells do that recognize mhc I?

Answer 8

CD8 T cells are cytotoxic to mhc I presenters

Question 9

what do t cells do that recognize mhc II?

Answer 9

CD4 t cells help activate APC via cytokines, cell-surface contact mediated stimulation

Also, recognize B cell MHC II (Ab that binds Ag) and help B cell activate

Question 10

what are the two cells that are cytotoxic?

Answer 10

CD8 T cells

Natural Killer cells

Question 11

mechanism of cytolysis?

Answer 11

specific recognition

release of lytic granules via cytoplasmic rearrangement and release

Question 12

what kinds of cells are lysed?

Answer 12

virally infected cells

infected cells with cytoplasmic bacteria

neoplastic cells

Question 13

what are the two main categories of helper T cells?

Answer 13

Th1

Th2

Question 14

Th1 do what?

Answer 14

post-regulatory molecules and cytokine release that help cells do cell-mediated responses

Question 15

Th2 do what?

Answer 15

help Ab-mediated responses (or humoral responses)

Question 16

what are the two major cytokines that differentiate?

Answer 16

Th1 – IFN-gamma –> cell-mediated responses

Th2 – IL-4 –> Ab-mediated response (also release IL-10 for plasma cell differentiation effect)

Question 17

what are the choices for B cell development

Answer 17

1. become a plasma cell

2. become a memory b cell

Question 18

how does B cell become plasma cell

Answer 18

Th2 produces IL-10 and B cell becomes short-lived plasma cell that produces Ab

Question 19

how does B cell become memory B cell

Answer 19

Th2 cell produces IL-4 and B cell becomes long-lived memory cell

Question 20

discuss somatic hypermutation during B cell development

Answer 20

during b cell/t cell interaction, b cells modify their DNA for Ab.

in area that encodes the binding site

dependent on activation-induced cytidine deaminas (AID)

Question 21

discuss affinity maturation in b cell development

Answer 21

select for B cells that express Ab’s w/ high affinity for Ag and remove those that do not

Question 22

discuss isotype switching in b cell maturation

Answer 22

Th2 produce cytokines that induce b cell to change the heavy chain of Ig (maintain same Ag binding site)

DNA recombination

Question 23

isotype functions

Answer 23

IgM/IgG - trigger complement pathway

IgG - binds Fc receptors on NK cells and triggers antibody-dependent cell-mediated cytotoxicity (ADCC)
-from mother is able to cross placenta

IgA - transported across epithelial surfaces (important for immunity at mucosal surfaces)

IgE - triggers degranulation by Mast cells (allergic responses).

Question 24

cytokines and their effect

Answer 24

IL-4 (Th2) = promotes IgE (anti-helminth responses and allergy)

IFN-gamma (Th1) = promote IgG sub-classes (cell-mediate responses)

Question 25

how do T cells take on their specific cytokine production?

Answer 25

DC determine polarization of T cells via its own cytokine production

DC produces IL-12 –> Th1 cytokines by T cell

DC produces low IL-12 –> Th2 cytokines by T cell

Question 26

how do you favor cytotoxic cell differentiation in adaptive

Answer 26

CD4 Th1 cells can produce IL-2 that help activation CD8 T cells favoring cell-mediated responses.

IL-12 from DC also trigger this

Question 27

what determines DC IL-12 production?

Answer 27

The nature of the PRR stimulation

Thus, the initial, innate stimulation (type of pathogen) determines the characteristics of the adaptive immune response