[Effect of Mycoplasma arthritidis on the recovery of erythropoiesis in mice treated with 5-fluorouracil].

M. arthritidis injected into B6AF1 hybrid mice 24 hours after 5-FU administration was shown to promote rapid erythropoiesis recovery in the spleen as measured by 59Fe incorporation M. arthritidis injected 4 hours after the drug or 4 hours before it was less effective. When inoculated 24 hours before 5-FU, M. arthritidis caused retardation of erythropoiesis recovery. The splenic 59Fe incorporation rise in all the cases paralleled the increase in cellularity with an overshoot at day 10-15 after 5-FU administration. In the femoral bone marrow, 59Fe incorporation was decreased in the mycoplasma-infected mice compared with the mice which received the drug alone. The results indicate that M. arthritidis is likely to trigger the resting hemopoietic precursor cells into the proliferative cycle. Another possible mechanism of M. arthritidis action might involve the increased migration of erythroid cell from the bone marrow to the spleen. The mode of M. arthritidis action on hemopoiesis in mice is different from that of bacterial endotoxin and erythropoietin.