Circulating immune complexes and dermatologic diseases

Immune complexes are products formed by the noncovalent union of antibody and antigen. Formation of immune complexes usually benefits the host by clearing antigens from the circulation. In some instances however, immune complexes are deposited in tissues with subsequent inflammation and tissue damage. The physiochemical characteristics of the immune complex, the status of the host's reticuloendothelial system, and the duration of exposure to antigen all influence the possibility of immune complex-mediated damage to tissues. Examples of this mechanism of injury are seen in serum sickness, systemic lupus erythematosus, and leukocytoclastic vasculitis. It is likely that the development of sensitive and reliable antigen-specific tests will provide more definitive information about the analysis of immune complex mediated injury.