Flashcards in T Cell Receptor Deck (20):
What is the function of MHC?
Monitor IC environments by presenting short peptide fragments on surface of cell to T cell to either signal response against foreign protein
How do you get diversity of TCR? (5)
1. recombination of VDJ segments
2. recombination of different number of gene segments
3. imprecise joining by RAG
4. P and N nucleotide addition by TdT
5. Assembly of different combos of rearranged TCR chains (alpha/beta or delta/gamma)
Does TCR have affinity maturation?
No, because it doesn't have somatic hypermutation
What do cytosolic peptides bind to? What are they presented to? What is the effect on presenting cell?
-binds MHC class I, present to CD8, and causes cell death
What do intravesciular pathogens bind to? What are they presented to? What is the effect on presenting cell?
-binds MHC class II, presents to CD4, and activates the APC to kill intravesicular bacteria and parasites
What do extracellular pathogens and toxins bind to? What are they presented to? What is the effect on presenting cell?
-binds MHC class II, presents to CD4, activates B cells to secrete IG to eliminate EC pathogen
Is this affinity of TCR for Ag weak or strong compared to Ab?
What region of the MHC protein do CD4 and CD8 recognize?
constant region, can interact with any MHC class II or class I protein respectively
What does gamma-delta TCR recognize?
3D shape of MHC molecule or Ag, not dependent on peptide held by MHC
How do superantigens work?
-recognizes outside constant regions of TCR and MHC to bind both in a nonspecific manner
-increases frequency of T cell response from 1 in 10^4 to 10^5 to 1 in 4 to 20 to get huge cytokine release
Does superantigen have any specificity?
-has specificity for certain VB segments, increases susceptibility for certain people
What HLA types make up class I MHC? class II?
for class I, HLA-A, HLA-B, HLA-C (homodimer)
for class II, HLA-D (heterodimer)
Where does the diversity come from for class I MHC? Class II?
for class I, diversity comes from number of alleles (6) since it's a homodimer
for class II, diversity comes from heterodimer arrangments
Which class of MHC is expressed on all nucleated cells?
MHC class I
What class of MHC is expressed on APCs?
MHC class II to allow interact with CD4 T cells so it can secrete cytokines to help B cells
What is the structure of MHC class I? Which subunits make up the binding groove?
-alpha 1, 2, 3 (transmembrane), beta 2
-alpha 1 and 2 make up binding groove
What is the structure of MHC class II? Which subunits make up the binding groove?
-alpha 1, 2 (transmembrane), beta 1, 2 (transmembrane)
-alpha 1 and beta 1 make up the binding groove
Which MHC class has a closed off binding groove that fits smaller peptides only?
Which class of MHC do extracellular pathogens present from?