In vitro studies on the mitogenic activity of mycoplasmal species toward lymphocytes.

The observed mitogenic activity of many mycoplasmal species provided the impetus for studies on this biologic manifestation. Studies designed to define the rat lymphocyte populations activated in vitro by Mycoplasma pulmonis showed that both B and T cells are activated. On the other hand, Mycoplasma neurolyticum induces nonspecific blastogenesis of the B-cell population of both rats and mice. These results and those of other workers suggest that the lymphocyte subpopulations activated by mycoplasmas differ with the mycoplasmal species and the origin of the lymphocytes. Further, one mycoplasmal species activates lymphocytes obtained from different species. Experiments performed to localize and define the biochemical nature of mitogens of M. pulmonis demonstrated that membranous outer-surface proteins are major constituents of the mitogenic factors. Membrane carbohydrates, but not lipids, may also be involved in the mitogenicity of M. pulmonis. Further studies establish a direct correlation between mitogenicity and pathogenicity of M. pulmonis in rats.