Flow cytometric phenotyping of platelet HPA-1a antigen: donor screening for a case of neonatal alloimmune thrombocytopenia due to anti-HPA-1a antibodies

Neonatal alloimmune thrombocytopenia can effectively be treated by transfusing compatible platelets to the affected newborn, but typed, compatible platelets are not generally available. For a case of probable neonatal alloimmune thrombocytopenia due to anti-HPA-1a, part of the donor population of the regional blood bank was phenotyped to find HPA-1a-negative platelets. A flow cytometric technique was used, which is reliable, rapid, and relatively simple and therefore well suited for large-scale screening. Using this method, several HPA-1a-negative donors were identified, and one of them donated platelets that were successfully transfused to the thrombocytopenic newborn. Immunohematology 1995;11:125–128.