MYCOPLASMAL INDUCTION OF CYTOKINE PRODUCTION AND MAJOR HISTOCOMPATIBILITY COMPLEX EXPRESSION

The mycoplasmas are a diverse set of bacteria that, in the course of t heir interactions with cells of the immune system, have a wide range o f immunomodulatory effects. These effects include polyclonal stimulati on of proliferation of T and B lymphocytes; activation of cytolytic ac tivity of macrophages, natural killer cells, and cytotoxic T cells; an d stimulation of production of cytokines (interleukin IL!-1, IL-2, IL -4, IL-6, interferon IFN!-alpha, IFN-beta, IFN-gamma, tumor necrosis factor-alpha, and granulocyte-macrophage colony-stimulating factor GM -CSF!) by immunocompetent cells. Mycoplasmas have also been shown to i nduce major histocompatibility complex (MHC) expression in macrophage cell lines and cultures. This report demonstrates that induction of MH C expression by mycoplasmas is directly due to increases in the transc riptional activity of MHC genes. Experiments attempting to determine i f the mechanism responsible for these increases in MHC expression requ ires the production of cytokines have demonstrated that production of IFN-gamma, IL-4, and GM-CSF is probably not involved.