Cell mediated immunity

Cell mediated immunity Types of T cells formed Helper T cells Cytotoxic T cells. Suppressor T cells

Lymphokines Low molecular weight regulatory proteins Lymphokines secreted by lymphocytes Interleukin 2 Interleukin 3 Interleukin 4 Interleukin 5 Interleukin 6 Granulocyte-monocyte colony stimulating factor, Interferon  .,.

FUNCTIONS OF HELPER T CELLS Specific Regulatory functions of the lymphokines. Stimulation of growth and proliferation of cytotoxic T cells and suppressor T cells. Stimulation of B-Cell Growth and Differentiation to Form Plasma Cells and Antibodies. Activation of the Macrophage System. Feedback Stimulatory Effect on the T-Helper Cells

Functions of Interleukins

Cytotoxic T cells

Cytotoxic T Cells Are “Killer” Cells The cytotoxic T cell is a direct-attack cell that is capable of killing microorganism. The receptor proteins on the surfaces of the cytotoxic cells cause them to bind tightly to the organisms or cells that contain the appropriate binding-specific antigen.

secrete perforins that punch holes in the membrane of the attacked cell. attacked cell swollen ,dissolves thereafter. cytotoxic cells can pull away from the victim cells and can move on to kill more cells.

The cytotoxic cells also play an important role in destroying cancer cells heart transplant cells cells foreign to the person’s own body.

Suppress functions of both cytotoxic and helper T cells. Suppressor T cells: Suppress functions of both cytotoxic and helper T cells. Limit the ability of immune system to attack body’s own tissues Called Immune Tolerence. Suppressor & helper T cells also called as regulatory T cells.

Failure of the Tolerance Mechanism Causes Auto-immune Diseases. Rhematic fever Glomerulonephritis Myesthenia Gravis Systemic lupus erythematosus(SLE)

Functions of lymphokines Growth and proliferation of Cytotoxic T cells Suppressor T cells B lymphocytes (specially interleukins 4,5,6) Plasma cells Production of antibodies Activation of macrophages Positive feed back effect on Helper T cells themselves Absence of TH & interleukins→ AIDS

CTL Contacts a Tumor Cell CD8 T Cell Tumor Cell

Membrane Damage to the Tumor Cell

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