Cytokines induced in vitro by Mycoplasma mycoides ssp. mycoides, large colony type

Septicemic disease in goats and sheep caused by the large colony type of Mycoplasma mycoides ssp. mycoides has clinical and pathological features in common with septic endotoxemia. We studied the ability of the mycoplasma to induce mediators of biological responses to endotoxin, such as TNFα, IL-1α, IL-6 and nitric oxide. Heat-killed suspensions of mycoplasmas in a concentration of 25 μg protein ml−1 induced all mediators in macrophages from peritoneal cavity and bone marrow of both C3HHeN (LPS responsive) and C3HHeJ (LPS low-responsive) mice. Lipopolysaccharide (LPS) in a concentration of 100 ng ml−1 induced the mediators in C3HHeN derived macrophages, only. Simultaneous stimulation of macrophages with interferon-γ enhanced the secretion of nitric oxide (measured as nitrite) but not the cytokines. We conclude that heat-killed Mycoplasma mycoides ssp. mycoides, large colony type, has cytokine inductive activity similar to bacterial endotoxin, but with an induction mechanism different from LPS.