Posttransfusion purpura: conversion of PLA1-negative platelets to the PLA1-positive phenotype by stored plasma is not due to the presence of soluble PLA1 antigen.
Three previous articles have reported a PLA1 antigen in the plasma of stored blood which is capable of binding to PLA1-negative platelets in the presence of divalent cations, rendering them PLA1 positive. Such a mechanism could explain the enigma of posttransfusion purpura (PTP), i.e., severe thrombocytopenia in a healthy subject with PLA1-negative platelets secondary to the infusion of blood containing PLA1-positive platelets. We find that the PLA1 antigen of stored blood is due to the presence of platelet fragments which can be removed by centrifugation and that divalent cation-chelating agents play no role in the apparent binding of these fragments to platelets. The apparent conversion of PLA1-negative platelets to the PLA1-positive phenotype by incubation with stored plasma from a PLA1-positive subject is due to the cosedimentation of platelet fragments with the platelets. No soluble PLA1 antigen was found in the plasma of five patients with acute posttransfusion purpura.
Ehmann
W C
WC
Department of Medicine, New York University Medical School, New York 10016.
Dancis
A
A
Ferziger
R
R
Karpatkin
S
S
D016824:Antigens, Human Platelet; D001792:Blood Platelets / Q000276:immunology*; D000939:Epitopes; D006801:Humans; D039661:Integrin beta3; D007519:Isoantigens / Q000032:analysis*; D010641:Phenotype; D010980:Platelet Membrane Glycoproteins / Q000032:analysis; D011696:Purpura, Thrombocytopenic / Q000097:blood / Q000209:etiology*; D065227:Transfusion Reaction
D016824:Antigens, Human Platelet; D000939:Epitopes; C061248:ITGB3 protein, human; D039661:Integrin beta3; D007519:Isoantigens; D010980:Platelet Membrane Glycoproteins