Molecular mimicry between host and pathogen: examples from parasites and implication

The studies summarized in this paper suggest that parasites may trigger act ivation of autoimmune mechanisms. The association between parasites and aut oimmunity could by manifested by the development of pathogenic anti-parasit ic antibodies and cytotoxic T cells that attack and damage self tissues as a result of molecular mimicry between host and parasites. On the other hand , the homology between self and parasitic antigens may enable parasites to protect themselves from the immune system and to induce a state of immunosu ppression. Although classic autoimmune diseases have not been shown to be m ore common amongst patients with chronic parasitic infections than in the g eneral population, it is clear that autoimmune activity does occur in patie nts with chronic parasitic infections. It is possible that infection with p arasites and other microbial agents may be followed by the activation of th e immune system and, in genetically predisposed individuals, by loss of fun ctional tolerance to self, activation of autoreactive cell that leads to pr ogression to an overt autoimmune disease. (C) 1999 Elsevier Science B.V. Al l rights reserved.