The role of cytokines in polymyositis: interferon-gamma induces class II and enhances class I major histocompatibility complex antigen expression on cultured human muscle cells.

Aberrant expression of class II major histocompatibility complex molecules has been found on target cells of various autoimmune diseases, including muscle fibers in patients with polymyositis-dermatomyositis. In this study the effects of a number of recombinant human cytokines, individually and in combination, on class I and class II molecule expression by cultured human muscle cells were examined with monoclonal antibodies and an immunoperoxidase technique. The following cytokines were tested: interferon-gamma, tumor necrosis factor-alpha, tumor necrosis factor-beta, interleukin-2, interleukin-1 alpha and interleukin-1 beta. Only IFN-gamma induced expression of class II molecules in muscle cells. It also enhanced the preexisting class I molecule expression by muscle cells. These findings suggest that IFN-gamma is involved in the aberrant expression of major histocompatibility complex molecules in the affected muscles of patients with polymyositis-dermatomyositis.