Studies on Platelets : III The Absence of "Selective Sequestration" and Destruction of Platelets by the Spleen in "Idiopathic" Thrombocytopenic Purpura

1. The question of "selective sequestration" of platelets by the spleen in the pathogenesis of thrombocytopenia of idiopathic thrombocytopenic purpura (I. T.P.) was evaluated by means of direct experiments at operation. Observations were made on: (1) differences in platelet number and function between blood collected from the splenic artery and splenic vein; (2) platelet level of the splenic pulp in 2 cases of I.T.P.; (3) effect of the injection of platelet-rich 1) blood in the peripheral circulation on the platelet level in the blood from the splenic artery and splenic vein; (4) effect of the direct injection of platelet-rich blood in the splenic artery on the number of platelets in the splenic artery and splenic vein blood.

2. No significant differences in platelet number or function could be found in samples of blood collected from the splenic artery and vein in cases with I.T.P. or other pathologic conditions. In 2 cases of I.T.P., splenic pulp blood and blood from the peripheral circulation showed a comparable number of platelets, in respect to the various hematocrit readings. The injection of platelet-rich blood in the peripheral circulation failed to establish a difference in platelet count between blood from the splenic artery and splenic vein. No significant diminution of the number of platelets in the splenic vein blood followed the direct injection of platelet-rich blood in the splenic artery. A similar result was observed in 1 case of hereditary spherocytosis where the spleen admittedly does not sequester platelets.

3. The results of these various experiments failed to indicate any "selective sequestration" of platelets by the spleen in "idiopathic" thrombocytopenic purpura.