micro ch16 L3
Perfornin granzyme cytotoxic pathway
cytoplasm if cytotoxic T cells has vesicles containing 3 key protein cytoxins perforin and granzyme
perfornin- performing cytolytic protein found in the granules of cytotoxic T lymphocytes and natural killer cells
Granzyme- serine protease released by cytoplasmic granules with in cytotoxic T cells and natural killer cells
Both used in natural killer cells in conjunction with antibody dependant cellular toxicity
Activation of cytotoxic T cell clones and their functions
adaptive initiated response do not initiate at any site of infection but move so in the lymph nodes
1-antigen presentation
2-helper T cell differention
3-clonal expansion
4-self stimulation
cytotoxic cells kill in 2 different pathways
Perfornin granztme pathway continued
cytotoxic T cell first attaches to its target, vesicles, containing the cytotoxins release their contents
having forced its target to commit suicide, the cytotoxic T cell disengages and moves on to another infected cell
CD95 cytotoxic pathway
cell mediated cytotoxicity
requires essential glycoprotein CD95, thats in cytoplasmic membranes in many human body cells
T cell that is activated comes into contact with its target like a TCR or the CD95L receptor it binds to CD95 on the target
Memory T cells
activated T cells
become functional immediately
T cell regulation
Body carefully regulates cell mediated immune responses so that T cells do not respond to autoantigens
Requires several signals from ann antigen presenting cells to activate
regulatory T cells also modulate cytotoxic T cells by mechanisms that are beyond the scope of our descision