title: Procoagulant effect of incompatible platelet transfusions in alloimmunized refractory patients.
abstract: The clinical effectiveness of platelet transfusion in refractory patients is still a subject of debate. We have evaluated the possible hemostatic effect of platelet transfusion in 16 alloimmunized thrombocytopenic patients whose platelet counts were less than 20,000/microliters. Platelet concentrates were always obtained by apheresis procedures from incompatible donors. The posttransfusion platelet recovery was greater than 15% only in 3 cases. In the first 6 patients, measurements of bleeding time performed immediately before transfusion were in all cases longer than 30 min and did not change significantly 10 and 60 min after platelet transfusions. In all patients, ex vivo perfusion experiments with Baumgartner's platelet adhesion model, using native nonanticoagulated blood, were performed immediately before and 10 and 60 min after transfusion. No difference in platelet deposition onto the subendothelial surface was observed after platelet transfusion. Unexpectedly, the deposition of fibrin on the subendothelial surface was statistically augmented in the posttransfusion studies. Quantification of thrombin-antithrombin complexes (TAT) in plasma showed statistically significant elevations (p < 0.01) in the posttransfusion samples (31.9 +/- 12.6 vs. baseline 5.8 +/- 1.7 ng/ml), not justified by TAT levels in the transfused material (2.3 +/- 0.17 ng/ml). Transfusion of incompatible platelets to refractory patients may activate coagulation mechanisms in the absence of an increase in peripheral platelet count.
authors.affiliation: Servicio de Hemoterapia y Hemostasia, Hospital Clinic, Barcelona, Spain.
authors.forename: R
authors.initials: R
authors.lastname: Mazzara
authors.forename: G
authors.initials: G
authors.lastname: Escolar
authors.forename: M
authors.initials: M
authors.lastname: Garrido
authors.forename: C
authors.initials: C
authors.lastname: Sanz
authors.forename: A
authors.initials: A
authors.lastname: Pereira
authors.forename: R
authors.initials: R
authors.lastname: Castillo
authors.forename: A
authors.initials: A
authors.lastname: Ordinas
mesh_terms: D001787:Blood Group Incompatibility; D006487:Hemostasis; D006801:Humans; D007519:Isoantigens / Q000276:immunology*; D010973:Platelet Adhesiveness; D010976:Platelet Count; D017713:Platelet Transfusion; D013921:Thrombocytopenia / Q000097:blood* / Q000276:immunology
chemical_list: D007519:Isoantigens