immunity 2 Flashcards
2 subgroups of T cells
Helper cells and cytotoxic lymphocytes
what molecules are expressed on the surface of helper cells
CD4
what molecules are expressed on the surface of cytotoxic lymphocytes
CD8
what are the subsets of CD4 cells
helper T cells - TH1, TH2, etc…
what are TH0 cells
naive helper T cells
what allows T cell receptors to engage with other proteins
transmembrane domains
what is a TCR
T cell receptor
in the TCR, what do the alpha and beta chains associate with
CD3 molecule complex (has intracellular component called the zeta chain)
what is CD3 made of
1xδ chain
1xγ chain
2xε chains
what does that zeta chain allow
binding to turn into signalling
what do TCRs recognise
processed antigen in the form of peptides presented by MHC molecules on the cell surface
what molecules stabilise the interaction when an antigen is recognised by TCR
CD4 or CD8
3 examples of professional antigen presenting cells
dendritic, macrophage and B
what do APCs do
phagocytose dead and dying cells and pathogens, chop them up in proteolytic compartments and load the peptide fragments onto new MHC molecules
how do T cells engage APCs
via their TCR and they scan the surface of the APC for a peptide on MHC that they recognise
what happens if TCR find a peptide on MHC that they recognise
the T cell is stimulated to become an activated effector T cell, some of these also become memory cells
2 types of MHC molecules
MHCI and MHCII
what is MHCI and what does it do
major histocompatibility complex I - associates with 9-mer peptides, its present on all cells (except RBC and germ)
what is MHCI recognised by
CD8 T cells
what is MHCII and what does it do
major histocompatibility complex II - associates with 9-20mer peptides, it is only present on APCs
what is MHCII recognised by
CD4 T cells
what do CD4 (t helper) cells produce
cytokines
what influences which antibody isotype is produced
the type of cytokine
what can cytokines activate
granulocytes, macrophages, NK cells
