general_pathology_-_ch37_autoimmunity_

general_pathology_-_ch37_autoimmunity_ - AUTOIMMUNE...

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Unformatted text preview: AUTOIMMUNE DISORDERS Autoimmune Disorders (immune reaction to self-antigens) • Disorders in which the immune system produces auto-antibodies to an endogenous antigen • Immune system of the body reacts against its own tissue destruction • N.B. presence of auto-reactive antibodies or T-cells does not equate to autoimmune disease • Non-pathogenic auto-antibodies are demonstrated in otherwise healthy individuals • Many disorders have an auto-immune aetiology suspected, but not proven • Autoimmune diseases range from: – Localised tissue damage • Specific immune response directed against one particular organ or cell type – Multisystem diseases • Characterised by lesions in many organs and associated with a multiplicity of auto-Ab’s or cell-mediated reactions • Changes principally in CT & blood vessels of organs involved ‘collagen vascular’ or ‘ CT disorders’ • Therefore autoimmunity implies loss of self-tolerance Classification of Autoimmune Diseases Local single organ Probable:- Hashimoto thyroidistis- Autoimmune haemolytic anaemia- Autoimmune atrophic gastritis (pernicious anemia)- Autoimmune encephalomyelitis- Autoimmune orchitis- Goodpasture syndrome- Autoimmune thrombocytopaenia- Type I DM (IDDM)- Myasthenia gravis- Graves disease Possible:- Primary biliary cirrhosis- Chronic active hepatitis- Ulcerative colitis- Membranous glomerulonephritis Systemic multiple sites Probable:- Systemic Lupus Erythematosus- Rheumatoid arhtritis- Sjogren’s syndrome- Reiter syndrome Possible:- Inflammatory myopathy- Systemic sclerosis (scleroderma)- Polyarteritis nodosa Immunological Tolerance • State in which an individual is capable of developing an immune response against a specific antigen • Self- tolerance specifically refers to a lack of immune responsiveness to one’s own tissue antigens • Immunologically competent cells learn to recognize the body’s own antigens at an early stage • Central vs peripheral tolerance Central Tolerance Clonal deletion • Deletion of self reactive T- & B-lymphocytes during their maturation in central lymphoid organs • T-lymphocytes with receptors for body’s own antigens are removed/ destroyed in thymus during maturation of T-cells • Many self antigens not present in thymus T-cells bearing receptors for autoantigens escape into the periphery • Similar ‘slippage’ in B-cell system Peripheral Tolerance (Self-reactive T-cells that escape negative selection in thymus) Anergy • Prolonged/irreversible inactivation of lymphocytes induced by encounter with antigens • Inactivated cells can’t amplify the immune response • Cells do not react to presentation of antigen...
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This note was uploaded on 10/07/2010 for the course DBT 446 taught by Professor Dd during the Spring '10 term at Indian Institute of Technology, Guwahati.

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general_pathology_-_ch37_autoimmunity_ - AUTOIMMUNE...

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