Platelet recovery after induction of acute thrombocytopenia

After mild thrombocytopenia (about 50-100% of control platelet level), induced by injection of antiplatelet serum (APS), platelets increased at a fairly constant and moderate rate for about 4 days and reached a maximum count, greater than pretreatment levels, on the fifth day. After moderate to severe thrombocytopenia, an early moderate rate of platelet increase was succeeded within 2 days by a second more rapid rate that persisted for about 3 days. The maximum overshoot of the platelet count was usually less than twice the pretreatment level. After the largest doses of APS, the platelet count remained depressed for several days. Platelet response after acute thrombocytopenia induced with antiserum is therefore variable, depending on the level and duration of thrombocytopenia.