53-MHC and Antigen Presentation Flashcards Preview

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Flashcards in 53-MHC and Antigen Presentation Deck (44)
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1

T cells

effector cells of adaptive immune response, 3 types

2

CD8 t cell

t killer cells
recognize infected cells and kill them

3

CD4 t cell

t helper cells
regulate function of other cells and release cytokines

4

gamma delta t cell

like innate cells, mucosal immunity

5

activation of T cell

requires 3 signals
activation
survival
differentiation

6

signal 1 for t cell

activation
from TCR
activation of TCR by antigen/MHC

7

signal 2 for t cell

survival
from costimulatory receptors of antigen presenting cells
CD28 binding to B7.1 and B7.2

8

signal 3 for t cell

differentiation
from cytokines produced by antigen presenting cells

9

antigens

proteins or large polysaccarides that are recognized by T cells using TCR

10

epitopes

small portion of antigens recognized by TCR

11

TCR/MHC interactions

required for T cell activation, need 10-20 interactions, naïve cells need more

12

where are MHC class 1 found

nucleated cells
NOT RBC or platelets

13

MHC class 1 activate what

CD8 t killer to eliminate pathogens

14

where are MHC class 2

antigen presenting cells
macrophages
B cells
dendritic cells

15

MHC class 2 activate what

CD4 t helper to control adaptive immune response

16

MHC class 1 peptides

intracellular (mostly cytosolic proteins, some ER)
dendritic make extracellular

17

MHC class 2 peptides

extracellular
dendritic make intracellular

18

MHC class 1 structure

2 subunits
alpha-binding
beta 2 microglobulin-stabilize
bind short amino acids 8-10

19

anchor residues

amino acids on end that bind to MHC

20

loading MHC class 1

-chaperone calnexin facilitates forming MHC/b2microglobulin
-transfer to chaperone calreticulin/ERp57/tapasin that interacts with TAP
-peptides produced in cytoplasm and transferred to ER with TAP complex
-peptides cleaved to 8-10 using ERAAP protease and loaded onto MHC class 1
-released after high affinity peptide is loaded

21

viruses inhibiting MHC class 1

encode for protein to inhibit MHC class 1
evade CD8 T killer

22

combat viral suppression of MHC class 1

NK cells recognize cells with low MHC class 1 and kill them
(presence of receptors on NK that recognize MHC class 1 and suppress NK function)

23

loading MHC class 2

extracellular- pathogens loaded by phagocytosis, non specific antigens loaded by macropinocytosis
intracellular-loaded by autophagy

24

MHC class 2 structure

2 proteins: alpha and beta which make peptide binding cleft
bind loner peptides, 12-20 amino acids

25

MHC class 2 binding peptides

MHC class 2 made in ER and binds invariant chain then transported to endosome
Activation of antigen presenting cell acidifies endosome degrading invariant chain and proteins
peptides loaded onto MHC class 2 by HLA-DM

26

pathogen superantigens

bind TCR and MHC
from bacteria, virus, mycoplasmas
cause atypical activation of t cells and cytokines
create systemic toxicity and immune suppression needed for microbial pathogenicity

Septic Shock

27

CD4 T cell activation

different function depending on antigen presenting cell
dendritic-activate naive t cell
macrophage-cell mediated immunity
b cell-humoral immunity

28

Dendritic cell activating CD4

activate naive T cell for clonal expansion and differentiation into effector T cell

29

Macrophage activating Cd4

macrophage activation, activation of effector CD4 T cells at infection and inflammation
cell mediated immunity

30

B cell activating CD4

b cell activation and antibody production, humoral immunity