Effects of antiplatelet serum and thrombopoietin on the percentage of small acetylcholinesterase-positive cells in bone marrow of mice.

Megakaryocytopoiesis was evaluated in the marrow of mice after they had been injected with rabbit anti-mouse platelet serum (RAMPS) or a thrombocytopoiesis-stimulating factor (TSF or thrombopoietin). For controls, other mice were injected with normal rabbit serum or saline. All materials were given as single intraperitoneal injections; at frequent intervals of up to seven days the mice were killed. RAMPS caused severe thrombocytopenia in mice with significant rebound-thrombocytosis following five to seven days later. TSF did not significantly increase platelet counts of mice. Both RAMPS and TSF increased the proportion of the small acetylcholinesterase positive (SAChE+) cells in the marrow of mice which was elevated 3-fold above control values at 8-10 h after treatment. The percentage of SAChE+ cells returned to control levels by 48 h and to below control values by 64-168 h. These data indicate that both exogenous TSF and endogenously produced TSF released in response to acute thrombocytopenia caused a transitory increase in the percentage of SAChE+ cells in mice.