immune tolerance

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Immune tolerance : 

Immune tolerance The other side of the coin.

Slide 2: 

cattle of dizygotic twin

Immune tolerance : 

Definition: A type of specific unresponsiveness to an antigen induced by the exposure of specific lymphocytes to that antigen, but response to other antigens normally. Tolerogens: antigens that induce tolerance Immune tolerance

General features of Immunologic tolerance Tolerance is antigenic specific and results from the recognition of antigens by specific lymphocytes. Normal individuals are tolerant of their own antigens(self antigen)----- Self-tolerance. Foreign antigens may be administered in ways that preferentially inhibit immune response by inducing tolerance in specific lymphocytes---antigen induction.

Difference of Immuologic tolerance & immunodeficiency, immunosuppression : 

Difference of Immuologic tolerance & immunodeficiency, immunosuppression Immunodeficiency: any condition in which there is deficiency in the production of humoral and /or cell-mediated immunity---non-specificity to Ag Immunosuppression: The suppression of immune responses to antigens. This can be achieved by various means, including physical, chemical----non-specificity to Ag

Slide 6: 

Experiment of Medawar on immunologic tolerance

Mechanism of Immunologic Tolerance : 

Mechanism of Immunologic Tolerance Central tolerance Peripheral tolerance

Central tolerance : 

Central tolerance Central tolerance occurs in the central lymphoid organs as a consequence of immature self-reactive lymphocytes recognizing ubiquitous self-antigen.

Peripheral tolerance : 

Peripheral tolerance Peripheral tolerance was induced in peripheral organs as a result of mature self-reactive lymphocytes encountering tissue-specific self antigens under particular conditions

Central tolerance : 

Central tolerance Clonal deletion (apoptotic cell death) During maturation of lymphocytes in the thymus for T cell or in the bone marrow for B maturation, immature lymphocytes that recognize ubiquitous self-antigen with high affinity are deleted by negative selection

Clonal deletion:negative selection of T cells in the thymus : 

Clonal deletion:negative selection of T cells in the thymus

Negative selection of B cells inbone marrow : 

Negative selection of B cells inbone marrow

Peripheral tolerance : 

Peripheral tolerance Clonal anergy functional inactivation without cell death: lack co-stimulatory signal

To induce immunologic tolerance : 

To induce immunologic tolerance Prevent the rejection of organ allografts and xenografts Treat autoimmune diseases Treat allergic diseases

To terminate immunologic tolerance : 

To terminate immunologic tolerance To treat tumor enhance first signal or second signal To treat infection diseases

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