Platelet Sequestration in Man. I. Methods*

Abstract

Current methods of labeling platelets with chromium51 using ethylenediaminetetraacetate (EDTA) as an anticoagulant cause rapid hepatic sequestration of nearly all the transfused platelets. About 50% returned to the circulation but then were partially destroyed in the spleen. Less than one-third survived. Evidence is presented which indicates that EDTA is injurious to platelets. When an acid-citrate medium which buffered plasma at pH 6.5 was used as an anticoagulant, 36-85% of the labeled platelets survived (average 62%) and marked temporary sequestration did not occur. Studies in thrombocytopenic persons showed that circulating platelet Cr51 activity measured the true survival of such transfused platelets. The survival and sequestration of platelets was studied in normal subjects. The survival data support the concept that platelets die chiefly by a process of senescence. External scintillation scanning of the various organs suggests that normally the majority of platelets are destroyed in the liver.