Immunology Lecture 8. Flashcards
What type of killing do cytokines do?
slow killing
What does fast killing?
perforin
CD28
receptor on T cells for the B7 co-stimulatory molecules (critical role in activation and proliferation of T cells after they first encounter antigen)
CTLA-4
high-affinity receptor for B7 molecules on T cells - critical role in SHUTTING OFF t cell response
B7
major T cell co-stimulatory molecules - bind to CD28 and CTLA-4
CD3
part of the TCR (Tcell receptor) complex - escorts the TCR to cell membrane and helps with signal transduction
What is the difference between TCR and immunoglobulin genes?
no somatic mutation of TCR genes
Which has more diversity? TCR or immunoglobulin? Why?
TCR - more junctional diversity
What is the difference in recognition by immunoglobulin and TCR?
anitbodies recognize surface structures (proteins, carbs, lipids), TCR recognizes short peptide fragments
Why do antibodies have stronger affinity than TCR/MHC?
somatic mutation makes it stronger
How do the subunits of MHC class I and II differ?
class I: alpha 1,2,3 and beta 2 (to help stabilize) class II: alpha 1 and 2 and beta 1 and 2 (longer peptides that are more specific)
What is required for delivery of signal to T cell?
recognition of both MHC and peptide, and CD3 to deliver signal. can also have non self MHC class II which will respond as self MHC presenting foreign antigen
What binds CD4?
MHC class II
What binds CD8?
MHC class I
How do gamma/delta TCR receptors differ from alpha/beta?
they are more similar to NK receptors because they can recognize MHC or antigen by themselves
What is the MHC haplotype?
one MHC allele from each parent - expressed codominantly, 3 different genes on each allele (can have 6 different MHC genes) - more homogeneity, more susceptible to disease
How can you tell if an allele has an association with a disease?
Relative risk (>1 = association)
How is antigen processed by MHC class I?
newly synthesized proteins are ubiquinated, then fragmented into peptides by the proteasome, —> peptides attach to TAP protein in membrane of ER —> complex moves into lumen, peptide is placed in binding groove of MHC class I, then complex goes to cell surface
How is antigen processed by MHC class II?
ingested antigen taken into phagolysosome and fragmented by proteases —> peptides move to endosomal compartments and placed in binding groove of MHC class II, displacing CLIP, then complex is carried to surface
What is CLIP?
classII associated invariant chain peptide: binds MHC class II groove to prevent the binding of self-peptide fragments
What is a super antigen?
high stimulation of T cells with certain v genes (causes toxic shock, sepsis) - no antigen needed - causes bridge between TCR and MHC
