Platelet alloantibodies in transfused patients.
BACKGROUND
Patients receiving cellular blood components may form HLA antibodies and platelet-specific alloantibodies.


METHODS
Serum samples from a cohort of 252 patients with hematologic or oncologic diseases who are receiving cellular blood components were studied for platelet-reactive antibodies. Specificity of platelet alloantibodies was determined with a panel of typed platelets


RESULTS
Platelet-reactive antibodies were detected in the sera of 113 patients (44.8% of 252), HLA antibodies in the sera of 108 (42.9%), and platelet-specific antibodies in the sera of 20 (8%). The following platelet-specific antibodies were identified: anti-HPA-5b (n = 10), anti-HPA-1b (n = 4), anti-HPA-5a (n = 2), anti-HPA-1a (n = 1), anti-HPA-2b (n = 1), anti-HPA-1b+5b (n = 1), and anti-HPA-1b+2b (n = 1). Fifteen sera from the 108 patients with anti-HLA (13.9%) contained additional platelet-specific alloantibodies, while in 5 sera, platelet-specific alloantibodies only were detected: anti-HPA-5b (n = 4) and anti-HPA-1a (n = 1). Of the 108 sera with HLA antibodies, 29 (26.9%) showed discordant results when studied with the lymphocytotoxicity test and the glycoprotein-specific immunoassay. Ten sera contained panreactive antibodies against platelet glycoproteins (GP) IIb/IIIa, GPIa/IIa, and/or GPIb/IX. Alloimmunization occurred in 58.3 percent of female patients with previous pregnancies, but in only 23.3 percent of those without previous pregnancies (p = 0.0049).


CONCLUSIONS
Platelet alloantibody specificities in transfused patients (predominantly anti-HPA-5b and -1b with antigen frequencies <30% among whites) differ significantly from those observed in patients with neonatal alloimmune thrombocytopenia or posttransfusion purpura, in whom anti-HPA-1a (antigen frequency >95%) is the most prevalent specificity. HLA antibody detection yields discordant results when the lymphocytotoxicity assay and a glycoprotein-specific immunoglobulin-binding assay are used.
Kiefel
V
V
Department of Transfusion Medicine, University of Rostock, Rostock, Germany. volker.kiefel@med.uni-rostock.de
König
C
C
Kroll
H
H
Santoso
S
S
D016824:Antigens, Human Platelet / Q000276:immunology; D001792:Blood Platelets / Q000276:immunology*; D001803:Blood Transfusion; D005260:Female; D006680:HLA Antigens / Q000276:immunology; D006801:Humans; D007518:Isoantibodies / Q000276:immunology*; D007519:Isoantigens / Q000276:immunology; D008297:Male
D016824:Antigens, Human Platelet; D006680:HLA Antigens; D007518:Isoantibodies; D007519:Isoantigens