10. Normal antigen Antigen presenting cell (APC) Phagocytose invading bacteria The CD4+ T cell gets activated and proliferates clonally Broken down bacterial antigens are processed and expressed on the surface of MHC II Each processed antigen is recognized by specific T cell receptor (TCR)
11. Super antigen Super antigen binds directly to MHC II (non antigen binding domain) It is then able to bind to non matching TCR Leads on to activation of more than 10% of the circulating lymphocytes Massive release of inflammatory mediators