ANTIGEN PROCESSING and PRESENTATION

1) Uptake of antigen by APC's: PATHOGEN, PAMP, TLR (depending on the pathogen)

APC's = dendritic cells, B cells, and macrophages (PROFESSIONAL) MHC Class II

Phagocytes = All nucleated cells (MHC Class I) ex: viruses, anybody can get them!

2) Particular APC depends on where the pathogen comes from:A) MHC Class I: intracellular B) MHC Class II: extracellular

*Recognition of antigen (HLA + T cell Receptor)

T cell response/activation depending on corresponding MHC Class molecule A) MHC Class I = CD8+ T cytotoxic (kill)

B) MHC Class II = CD4+ T helper (mediate killing, alert other T cells, etc.)

5) Effector T cells encounter antigens and are activated

Then Exert cellular function:

T cell effector function

3) Cellular expansion and differentiation (into effector and memory cells)

4) Migration: interact with other cells and go to site of infection