title: The first case of alloantibody against human platelet antigen-15b in Japan: possible alloimmunization by a hydatidiform mole.
abstract: BACKGROUND
  The involvement of the human platelet antigen (HPA)-15 system in neonatal alloimmune thrombocytopenia (NAIT) has been reported in various populations, but not in the Japanese population. In Japan, the mixed passive hemagglutination assay (MPHA) is used for detection of HPA alloantibodies. However, most of the reported cases of HPA-15 incompatibility are based on the monoclonal antibody immobilization of platelet antigen (MAIPA) assay or immunoprecipitation; thus there is a possibility that HPA-15 alloantibodies are not efficiently detected by the MPHA, and currently, the causative antibody is not detectable in approximately half of the suspected NAIT cases in Japan.
  
  
  METHODS
  We examined the sera of mothers from NAIT cases, previously with undetected HPA antibodies by MPHA, using the MAIPA technique. Sera from 90 mothers of suspected NAIT were tested by MAIPA for the presence of anti-HPA-15 alloantibodies.
  
  
  RESULTS
  Anti-HPA-15b was detected in one case. This case was a mother in the first pregnancy diagnosed as hydatid mole-coexisting fetus, and the baby was born with suspected NAIT. The familial analysis revealed compatibility of HPA-15 genotype between the mother and the baby (both HPA-15a/a), but incompatibility with the paternal one (HPA-15a/b). The hydatid mole's tissue was genotyped as HPA-15b positive. Besides anti-HPA-15b, maternal sera contain strong HLA Class I antibody
  
  
  CONCLUSIONS
  Here we reported the first case of anti-HPA-15 in Japan. Alloimmunization against the hydatid mole seems to be responsible for the production of HPA-15b alloantibody. This antibody, however, did not apparently involve in the development of NAIT of the newborn, the coexisting anti-HLA Class I being the possible cause.
authors.affiliation: Department of Transfusion Medicine, The University of Tokyo, Tokyo, Japan.
authors.forename: Mika
authors.initials: M
authors.lastname: Matsuhashi
authors.forename: Nelson H
authors.initials: NH
authors.lastname: Tsuno
authors.forename: Michiru
authors.initials: M
authors.lastname: Kawabata
authors.forename: Tomokazu
authors.initials: T
authors.lastname: Yokoyama
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Tazaki
authors.forename: Takeshi
authors.initials: T
authors.lastname: Takashima
authors.forename: Hidetaka
authors.initials: H
authors.lastname: Oda
authors.forename: Yukari
authors.initials: Y
authors.lastname: Kuroda
authors.forename: Yuji
authors.initials: Y
authors.lastname: Nagayoshi
authors.forename: Shoji
authors.initials: S
authors.lastname: Morita
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Shibata
authors.forename: Sentot
authors.initials: S
authors.lastname: Santoso
authors.forename: Koki
authors.initials: K
authors.lastname: Takahashi
mesh_terms: D015703:Antigens, CD / Q000276:immunology*; D005260:Female; D058851:GPI-Linked Proteins; D006386:Hemagglutination Tests; D006801:Humans; D006828:Hydatidiform Mole / Q000276:immunology*; D007518:Isoantibodies / Q000097:blood*; D009363:Neoplasm Proteins / Q000276:immunology*; D011247:Pregnancy; D054098:Thrombocytopenia, Neonatal Alloimmune / Q000276:immunology*; D014594:Uterine Neoplasms / Q000276:immunology*
chemical_list: D015703:Antigens, CD; C120523:CD109 protein, human; D058851:GPI-Linked Proteins; D007518:Isoantibodies; D009363:Neoplasm Proteins