title: Thrombocytopenia caused by passive transfusion of anti-glycoprotein Ia/IIa alloantibody (anti-HPA-5b).
abstract: We describe a patient who developed transient and moderately severe thrombocytopenia (platelet count nadir 35 x 10(9)/L) after the transfusion of plasma. Using the technique of direct radioimmunoprecipitation, we showed that during the thrombocytopenia episode, the patient's platelets had IgG specifically bound to the glycoprotein (GP) Ia/IIa complex. Indirect radioimmunoprecipitation using serum from the plasma donor confirmed that anti-HPA-5b (anti-Zava) was the cause of GP Ia/IIa sensitization. The relatively mild thrombocytopenia, compared with passive alloimmune thrombocytopenia caused by anti-HPA-1a (anti-P1A1), may reflect the low copy number of HPA-5 compared with HPA-1. Direct radioimmunoprecipitation permits the detection of the GPs carrying the known platelet alloantigen systems, and this study suggests that this technique can be used to diagnose passive alloimmune thrombocytopenia.
authors.affiliation: Department of Medicine, McMaster University, Hamilton, Ontario, Canada.
authors.forename: T E
authors.initials: TE
authors.lastname: Warkentin
authors.forename: J W
authors.initials: JW
authors.lastname: Smith
authors.forename: C P
authors.initials: CP
authors.lastname: Hayward
authors.forename: A M
authors.initials: AM
authors.lastname: Ali
authors.forename: J G
authors.initials: JG
authors.lastname: Kelton
mesh_terms: D006801:Humans; D007518:Isoantibodies / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D010980:Platelet Membrane Glycoproteins / Q000276:immunology*; D011233:Precipitin Tests; D013921:Thrombocytopenia / Q000209:etiology*; D065227:Transfusion Reaction
chemical_list: D007518:Isoantibodies; D010980:Platelet Membrane Glycoproteins