Organ distribution and fate of human platelets: Studies of asplenic and splenomegalic patients

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Abstract
Little is known about the organ distribution and fate of human platelets. We investigated the kinetics, organ distribution, and fate of autologous 111 In-oxine-labeled platelets in 12 normal volunteers, four asplenic subjects, and four patients with splenomegaly. The initial recovery of infused 111 In-platelets from the circulation was 97.8 ± 9.8% (means ± SD) for asplenic subjects and 26.3 ± 5.9% for splenomegalic patients as compared to 59.2 ± 9.3% for normal controls. The mean platelet survival times as derived from the multiple-hit model were 9.2 ± 1.0 days for asplenics and 6.2 ± 0.6 days for splenomegalic subjects (8.4 ± 0.8 days for normals). At 30 min postinfusion, 79.4 ± 19.2% of the infused 111 In-platelets pooled in the spleen of splenomegalic subjects and 42.7 ± 12.2% in normal controls. There was 7.1 ± 2.0, 12.6 ± 3.7, and 29.3 ± 8.4% pooling in the liver of splenomegalic, normal, and asplenic subjects, respectively. At 10 days postinfusion, 37 and 24% of the 111 In-platelets were sequestered in the spleen and liver of normal control subjects, respectively. Similar figures for splenomegalic subjects were 71 and 14%, respectively. In asplenic subjects, 89% was sequestered in the liver. We conclude that spleen and liver are the primary sites of platelet destruction, accounting for 61% of infused 111In-platelets in normal volunteers and 85% in splenomegalies, while the liver is the primary site of platelet destruction, accounting for 89% in asplenic subjects.