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