Mycoplasma stimulates the production of oxidative radicals by murine peritoneal macrophages

Mycoplasmas and mycoplasma membranes have been shown to induce the production of inflammatory cytokines, including tumor necrosis factor α and interleukin-6, as well as nitric oxide, by mouse macrophages and rat brain astrocytes. Luminol-enhanced chemiluminescence was used as a sensitive method to show that Mycoplasma capricolum membranes induce mouse peritoneal macrophages to produce reactive oxygen radicals. Coincubation of the mycoplasma with a secondary stimulus, namely macrophage-activating factor or interferon-γ, increased the chemiluminescence. The augmentation was abolished by the nitric oxide synthase inhibitor N(G)-methyl-L-arginine, indicating the involvement of nitric oxide. The coproduction of superoxide and nitric oxide by the same cell allows the formation of the powerful oxidant peroxynitrite, which could be responsible for the increased chemiluminescence. Induction of oxidizing radicals by mycoplasmas may contribute to the clinical pathology seen in mycoplasma infections.