Hereditary thrombocytopenia with excessively prolonged bleeding time, corrected by infusions of platelet poor plasma.

In a family with hereditary thrombocytopenia, transfused normal platelets as well as their own platelets had a shortened survival in the patients' circulation (11). On the other hand, the patients' platelets survived normally when transfused to a normal recipient. Platelet-associated immunoglobulins or circulating platelet antibodies were not detected (immunofluorescence method). About 200 ml platelet poor plasma (PPP) from each of 4 normal donors was infused daily for 5 consecutive d to 1 afflicted family member, causing a rise of platelet count from 65 X 10(9)/l to 163 X 10(9)/l and a decrease of bleeding time from 28 to 11 min 7 d after the PPP was discontinued. The platelet count then gradually decreased and was 65 X 10(9)/l with a bleeding time of 30 min 16 d after the PPP was discontinued. In a repeated PPP infusion experiment a similar response was evoked. It is concluded that the afflicted family members must have a deficiency of some plasma principle necessary to keep platelets fit and circulating.