Platelet storage in the spleen in idiopathic thrombocytopenic purpura and congestive splenomegaly.

The kinetics of 51Cr-tagged platelets was studied in 10 patients with idiopathic thrombocytopenic purpura and in 8 patients with congestive splenomegaly. The surgically removed spleens were examined for their platelet content and for their microscopic structure. In idiopathic thrombocytopenic purpura the life-span of platelets was reduced, the number of platelets washed out from the spleen averaged 4.36 X 10(10)/100 g splenic tissue (intrasplenic platelet reserve). The index platelets per g splenic tissue/platelets per ml whole blood reflecting the tendency of platelets to concentrate in the spleen was 8.06. Microscopically, extensive phagocytosis of platelets by macrophages and a preserved lienal architecture were seen. In the group of congestive splenomegaly the life-span of platelets was not significantly shortened and the intrasplenic platelet reserve agreed with the figure found in idiopathic thrombocytopenic purpura. The spleen was characterized by fibroid degeneration and endothelial hypertrophy causing partial obstruction of the sinusoids. It is concluded that while the intrasplenic platelet reserve is nearly the same in idiopathic thrombocytopenic purpura and congestive splenomegaly, in idiopathic thrombocytopenic purpura hypersequestration while in congestive splenomegaly platelet storage predominates.