Autoimmune disease is a group of disorders in which the body's immune system improperly recognizes self-antigens (the body's own antigens - not foreign antigens) and induces an immune response that results in tissue destruction. Autoimmune disease can be either organ-specific (such as: Type I diabetes, Multiple sclerosis, Graves' disease, Hashimoto's thyroiditis etc.) or not organ-specific (Systemic lupus erythematosus, Rheumatoid arthritis, etc.). Although autoimmune diseases are mediated through various mechanisms and can be induced by multiple environmental or hereditary causes, they all are a result of a failure in immunological tolerance. Immune cells that are improperly selected in the thymus (T-cells) and bone marrow (B-cells) can result in an expansion of these cells when they encounter self-antigens and cause disease. To safeguard against this, there is a type of regulatory T-cell (T-regs) that recognizes self-antigens and suppresses auto-reactive cells that are improperly selected. A failure in T-reg-mediated tolerance can result in autoimmunity without a defect in selection due to the molecular mimicry of foreign microbes. Although there is no known cure for any autoimmune disease, treatment with immunosuppressants (such as ciclosporin a and rapamycin) can be effective at managing symptoms.

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