Diagnosis and treatment of immunological platelet refractoriness by histocompatibility.

Immunological platelet refractoriness occurs when polytransfused patients develop antibodies against donors' HLA class I antigens, HPA (human platelet antigens) and few cases against both systems. Flow cytometry crossmatch with the patient serum against platelets from several donors can determine whether the refractoriness is or is not of immunological origin. Patients with moderate sensitization will be given transfusions from donors with a negative platelets crossmatch; those who are hypersensitized will need to have antibodies assessed against a reactivity panel (RP) for HLA class I and HPA.