Immunomodulation In Vivo by the Mycoplasma arthritidis Superantigen, MAM

Abstract

Mycoplasma arthritidis produces a potent superantigen (MAM) that activates specific murine and human T lymphocytes to proliferate and secrete lymphokines. We show here that MAM also influences both T- and B-cell functions in vivo. Lymphocytes from mice injected with MAM exhibit a suppression of proliferative responses to MAM in vitro but only a partial suppression of responses to other mitogens. This T-cell anergy not only decreased contact sensitivity to dinitrofluorobenzene but also prolonged survival of skin transplants. In contrast, B-cell reactivity is increased following in vivo injection of MAM, as evidenced by enhanced antibody responses to sheep red blood cells and ovalbumin. Also, there is a marked decrease in the ability of splenocytes from MAM-injected mice to produce interleukin-2 (IL-2) but a marked increase in their ability to produce IL-4 and IL-6. The combined results suggest that MAM induces a lymphokine profile that favors activation of B-cell functions, with a resulting potential for triggering of autoimmune disease.

Stimulation of whole blood cultures in patients with ankylosing spondylitis by a mitogen derived fromMycoplasma arthritidis (MAS) and other mitogens

“…A similar in vitro anergy in peripheral T lymphocytes has been described in the mouse model for SEB [29]. Furthermore, MAS not only influences T-cell functions, but also increases monocyte activity by enhancing the production of IL-6 and IL-1/3 [11,12,30].…”

Heat shock protein of Mycoplasma salivarium and Mycoplasma orale strains isolated from HIV-seropositive patients.

“…They have been implicated in immunomodulatory actions such as immunosuppression and induction of autoimmune diseases 6,26,27) . The present study showed that mycoplasma species isolated from saliva samples obtained from HIV(‫)ם‬ and HIV(‫)מ‬ subjects produced HSPs.…”

“…Production of superantigens and of heat shock proteins (HSPs) is closely associated with changing host responses [1][2][3][6][7][8]21,22,26,27) . This study was designed to evaluate the significance of infections by M. salivarium and M. orale in HIV(‫)ם‬ patients.…”

Molecular Biology and Pathogenicity of Mycoplasmas

“…MAM has been found to enhance the responses of human and mouse B cells (85,97,461). Although MAM by itself did not trigger significant stimulation of isolated B lymphocytes, CD4…”

“…The potential of M. arthritidis to cause acute and chronic inflammatory arthritis in rodents, together with the discovery that this mycoplasma produces the potent superantigen MAM (83), prompted Cole and associates to investigate the effects of MAM in vivo. Although MAM by itself failed to induce chronic arthritis in mice (85), the investigators found that intra-articular administration of MAM to DA rats produced local joint inflammation and swelling that resolved a week later (67). Systemic injection of MAM into mice caused a temporary anergy of cell-mediated immune responses with a simultaneous enhancement of B-cell activation and differentiation (85).…”