title: Alloimmunization against Iy, a low-frequency antigen on platelet glycoprotein Ib/IX as a cause of severe neonatal alloimmune thrombocytopenic purpura.
abstract: Neonatal alloimmune thrombocytopenia (NAIT) is usually induced by platelet-specific antibodies against HPA-1a (Zwa) or HPA-5b (Bra). Recently, low-frequency alloantigens on the platelet glycoprotein (GP) IIb/IIIa complex have been discovered as a cause for NAIT. In this report, a new low-frequency platelet-specific alloantigen, Iy, is described which induced severe NAIT. The corresponding antigen was detected in 1/249 unrelated German blood donors. Antibody binding assays with trypsin-digested platelets (ELISA, immunoprecipitation with biotin-labelled platelets) indicate that the antigen is not localized on the glycocalicin moiety of GP Ib alpha, but may be situated on the remnant moiety of GP Ib alpha, GP IX or GPIb beta. Apparently, Iy is not related to the HPA-2 (Ko) antigen system.
authors.affiliation: Institute for Clinical Immunology and Transfusion Medicine, Justus-Liebig University, Giessen, Germany.
authors.forename: V
authors.initials: V
authors.lastname: Kiefel
authors.forename: M
authors.initials: M
authors.lastname: Vicariot
authors.forename: Y
authors.initials: Y
authors.lastname: Giovangrandi
authors.forename: H
authors.initials: H
authors.lastname: Kroll
authors.forename: M
authors.initials: M
authors.lastname: Böhringer
authors.forename: A
authors.initials: A
authors.lastname: Greinacher
authors.forename: C
authors.initials: C
authors.lastname: Breitfeld
authors.forename: S
authors.initials: S
authors.lastname: Santoso
authors.forename: C
authors.initials: C
authors.lastname: Mueller-Eckhardt
mesh_terms: D000328:Adult; D016824:Antigens, Human Platelet / Q000276:immunology*; D001792:Blood Platelets / Q000276:immunology*; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D007518:Isoantibodies / Q000276:immunology*; D008431:Maternal-Fetal Exchange / Q000276:immunology*; D019038:Platelet Glycoprotein GPIb-IX Complex / Q000276:immunology*; D011247:Pregnancy; D011696:Purpura, Thrombocytopenic / Q000276:immunology*
chemical_list: D016824:Antigens, Human Platelet; D007518:Isoantibodies; D019038:Platelet Glycoprotein GPIb-IX Complex