[Stimulation of erythropoiesis in mice with mycoplasma infections].

Mycoplasma arthritidis was shown earlier to induce erythropoietin-independent erythropoiesis in infected mice. This study demonstrated the increased 59Fe incorporation in the mouse spleen as early as day 4 after infection with M. arthritidis. It is known that inoculation of mice with low doses of actinomycin D (Act D) results in a specific suppression of erythropoiesis without impairing the endogenous erythropoietin production. In this study the mice were injected with Act D (80 microgram/kg body weight) daily for 5 days. One hour after the last injection the mice were sublethally irradiated and then infected with either M. arthritidis or A. laidlawii. The effect of Act D was completely reversed by both mycoplasmas which was shown by means of endogenous colony formation (there was almost no endogenous colony formation in the spleen of non-infected mice that were given Act D). The data indicate that the target cells for the mycoplasmas probably reside within the population of primitive erythropoietin-independent precursors.