Platelet Sequestration in Man. Ii. Immunological and Clinical Studies.

The mechanisms of platelet destruction and their sites of sequestration in disease states are poorly understood. Although recent studies have emphasized the importance of platelet isoantibodies in certain clinical situations (1-3), little is known of the effects of antibodies on platelets in vivo. In conditions such as idiopathic thrombocytopenic purpura, there is debate as to whether immune mechanisms are involved, and sites of platelet sequestration are unknown. The availability of a method for labeling platelets with Cr5' that allows most of the transfused platelets to remain viable and reduces the initial deposition of nonviable platelets in the liver and spleen (4) permits study of some of these aspects of platelet pathophysiology. We investigated the survival and sites of sequestration of platelets exposed to isoantibodies in vivo. Included in this paper are observations of pyrogenic reactions after immune platelet destruction. Studies in patients with idiopathic thrombocytopenic purpura and other platelet disorders are also described.