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Autoimmune conditions: causes, symptoms, diagnosis, treatment
Medical expert of the article
Last reviewed: 04.07.2025
Autoimmune conditions involve the production of antibodies to endogenous antigens. Cells bearing the antibody, like any cell with foreign particles on its surface, activate the complement system, causing tissue damage. Sometimes antigen-antibody complexes are involved in the damage mechanism (type III hypersensitivity reaction). Specific autoimmune disorders are discussed in other chapters of this publication.
Causes of Autoimmune Conditions
Several mechanisms of autoimmune damage can be named.
Autoantigens may acquire immunogenic properties through chemical, physical, or biological modification. Certain chemicals combine with host proteins, making them immunogenic (as in contact dermatitis). Drugs may induce some autoimmune processes through covalent binding to serum or tissue proteins. Photosensitivity is an example of physically induced autoallergy: ultraviolet light alters skin proteins to which the patient is allergic. Animal models have shown that persistence of viral RNA that is bound to host tissue alters autoantigens biologically, resulting in autoallergic disorders such as SLE.
Antibodies produced in response to a foreign antigen can cross-react with normal autoantigens (cross-reaction between streptococcal M-protein and protein structures of human cardiac muscle tissue).
Normally, autoimmune reactions are suppressed by specific regulatory T-lymphocytes. A defect in regulatory T-lymphocytes may be accompanied by or result from any of the above mechanisms. Anti-idiotypic antibodies (antibodies to the antigen-binding site of other antibodies) may interfere with the regulation of antibody activity.
Genetic factors also play a role. Relatives of patients with autoimmune disorders often have the same type of autoantibodies, and the incidence of autoimmune disorders is higher in identical than in fraternal twins. Women suffer from autoimmune diseases more often than men. Genetic factors determine predisposition to autoimmune conditions. In predisposed patients, external factors can provoke the disease (for example, certain medications can provoke hemolytic anemia in patients with G6PD deficiency).