Interactions between murine alveolar macrophages and Mycoplasma pulmonis in vitro.

In comparison to syngeneic fibroblasts, alveolar macrophages collected from Fischer 344 rats demonstrated a significant ability to decrease the growth rate of cell-associated Mycoplasma pulmonis, even in the absence of specific actimycoplasmal antibodies. However, when exposed to thallium acetate (a cytotoxic heavy metal), macrophages supported growth of mycoplasmas almost as well as did untreated fibroblasts. This suggests an active antimycoplasmal process operative in untreated macrophages. In contrast, mouse alveolar macrophages were not capable of exerting an antimycoplasmal effect unless rabbit anti-M. pulmonis antibodies were present. Paradoxically, mouse anti-M. pulmonis antibodies did not promote this effect.