Lecture 6: MHC and Ag Presentation to T cells Flashcards Preview

Immunology 2.0 > Lecture 6: MHC and Ag Presentation to T cells > Flashcards

Flashcards in Lecture 6: MHC and Ag Presentation to T cells Deck (32):
1

in order to activate T cells Antigens in host cells are broken up into ____ peptides (processed) and displayed by MHC molecules on their surface

linear

2

T T cell antigen receptor (TCR) only recognizes ____ Antigens (peptides) bound to MHC molecules 

linear peptides (processed) 

3

CD4 and CD8 attach to the _____ part of the MHC class II and MHC class I molecules, respectively

non-polymorphic (non-variant) 

4

is recognition of the peptide Ag by the TCR sufficient to activate the naive T cells 

  • No: co-stimulatory molecules are required together with co-receptors 

5

Th1 cells help ___ to get rid of intracellular microbes and help the development of ______ to kill virus-infected cells

  • Macrophages, CTLs 

 

6

Th2 cells are mainly involved in helping _____ cells develop into ____ and ____ 

B cells develop into memory cells and plasma cells that produce antibodies

7

The TCR is composed of _______ polypeptide chains

two (most are alpha and beta but some are are gamma and delta chains) 

8

The gamma/delta T cells have some of the characteristics of alpha/beta T cells, but have a 

broader specificity for unconventional Ag such as HSPs and phospholipids

9

The genes coding for TCR polypeptide chains are members of the 

Ig super family 

10

The T cell receptor complex consists of the TCR, the alpha/beta or gamma/delta dimer, in association with 

CD3

11

CD3 is a signaling complex composed of ___, ____ and ____ chains

gamma, delta, and epsilon

12

What are the three major class genes for Class I MHC

  • HLA-A
  • HLA-C
  • HLA-B
  • on chromosome 6

13

What genes are responsible for MHC class II

  • HLA-DR
  • HLA-DQ
  • HLA-DP
  • on chromosome 6

14

Class I MHC genes (HLA-A, HLA-B, and HLA-C) encode a polymorphic heavy chain which combines with _____ and is expressed on the surfaces of all nucleated cells 

beta2-microglobulin

15

Class II MHC genes (HLA-D) encode molecules (HLA-DP, HLA-DR, HLA-DQ) composed of two dissimilar ____________ (an alpha and beta chain), both of which contribute to the peptide-binding groove

polymorphic polypeptide chains 

16

MHC class I and class II are the peptide-binding domains of these molecules and bind peptides ranging from _____ and _____ amino acids residues, respectively 

8-10 (MHC class I)

10-20 (MHC class II)

17

Class I molecules are composed of a polymorphic alpha chain non-covalently attached to the ___________

non-polymorphic Beta2-microglobulin (beta2m)

18

class II MHC molecules are composed of a polymorphic alpha chain non-covalently attached to a 

polymorphic beta chain 

19

source of protein antigens for Class II MHC molecules

Endosomal/lysosomal proteins (mostly internalized from extracellular environment) 

20

Source of protein antigens for class I MHC molecules

Cytosolic proteins (mostly synthesized in the cell; may enter cytosol from phagosomes) 

21

Site of peptide loading for MHC class II

Specialized vesicles 

22

Site of peptide loading of MHC class I 

Endoplasmic reticulum

23

enzymes responsible for pepide generation for MHC class II 

Endosomal and lysosomal proteases (e.g. cathepsins) 

24

Enzymes responsible for peptide generation for MHC class I 

Cyoplasmic proteasome 

25

Molecules involved in transport of peptides and loading of MHC class II molceules

Invariant chain, DM

26

Molecules involved in transport of peptide and loading of MHC class I molecules 

TAP

27

Peptide Ags that bind to class II MHC complexes are from the ____ pathway while peptide antigens for class I MHC are taken from the ____ pathway

  • exogneous pathway (MHC class II)
  • endogenous pathway (MHC class I)

 

28

what is CLIP

  • Class II-associated invariant chain peptide
    • it 24-amino acid remnant of the invariant chain that is placed in the peptide binding site.  it is removed by HLA-DM (HLA-DM is a peptide exchanger that removes the CLIP and allows for the addition of other peptides) 

29

MHC class II (along with the invariant chain) is formed in the 

ER

30

What are the 3 major functions of HLA-DM

  • HLA-DM causes the dissociation of CLIP from the peptide binding groove of MHC II
  • HLA-DM stabilizes and prevents degradation of the empty MHC II
  • HLA-DM facilitates the binding of Ag fragments to the open, stabilized binding groove

31

How is CLIP formed 

the degradation of the invariant chain by proteolytic enzymes in the endosome. This forms the 24 amino acid invariant chain known as CLIP

32

What are immunodominant peptides

Applies to peptides presented by both class I and class II MHC molecules