Abstract
Several species of mycoplasmas including M. pneumoniae, the causative agent of human respiratory infection, were investigated for tumor necrosis factor-alpha (TNF-α) induction. The cytotoxic activity to Meth A cells of peritoneal macrophages purified from BALB/c mice was enhanced markedly when cultured with either viable or nonviable mycoplasmas. The supernatant of macrophage culture mixed with mycoplasmas, M. pneumoniae or A. laidlawii, showed a potent cytotoxic activity to TNF-α-sensitive but not to TNA-α-insensitive L cells. Addition of anti-TNA-α antiserum inhibited completely the cytotoxic activity of the supernatant, indicating that the cytotoxic activity is due mostly to TNF-α. These results strongly suggest that mycoplasmas possess an activity to induce TNF-α, which enhances the cytotoxic activity of macrophages and prevent infection with mycoplasmas in vivo.
