4.2. Mechanisms of autoimmune tissue injury

Immune responses can cause tissue injury and disorders called as hypersensitivity diseases. Hypersensitivity is a term of excessive or aberrant immune responses [4]. Tissue damage in autoimmune diseases can occur through several mechanisms, which are similar to three of the classical types of hypersensitivity reactions [5]:

1. Type II (caused by autoantibodies reactive with cell surface or matrix antigens):

Antibodies against cell and tissue may cause tissue and disease. IgM and IgG antibodies activate the phagocytosis of cells by binding to complement and Fc receptor- mediated leukocyte [4]. The reactions are caused by antibodies against self-protein antigens. Autoantibodies generated against cell surface antigens/extracellular matrix proteins may be cytotoxic (type IIA) or agonistic/antagonistic (type IIB). Autoantibodies to cell surface antigens may initiate cell destruction by complement- mediated lysis (cell destruction), phagocytosis, or antibodydependent cell-mediated cytotoxicity (ADCC) [5]. At Table 5, some examples of antibodymediated diseases are given.


Table 5. Antibody-mediated diseases.
