A mycoplasma extract highly enriched in lipoproteins can be prepared with Triton X-114. However free membrane lipids and capsule components are also co-extracted and therefore, the effects of such extracts cannot be exclusively attributed to lipoproteins unless appropriate control experiments are performed. This killing requires the presence of actinomycin D and resembles apoptosis. The physiological significance of this finding is unknown because the mycoplasmas by themselves have not been shown to induce apoptosis. We have studied the molecular interactions between spiralin, a mycoplasma lipoprotein, and immune cells.
Mycoplasma lipoproteins are potent immunogens and are major components of the mycoplasmal membranes.
Antigenic variability may explain the chronicity of mycoplasmal infection and thus further information on this issue would be valuable. Another mechanism often involved in immune system escape is molecular mimicry by structures of the parasite for its host. This strongly suggests molecular mimicry of the GLF for the sugars exposed on human cell surfaces. Possibly GLF, recently characterized as a capsule-like material, protects M. penetrans from host phagocytosis. Altogether, there is various evidence for complex cellular and molecular activation of the immune system by mycoplasmas.