Accurate Rh phenotype determination by reticulocyte mRNA typing shortly after multiple transfusions.

Alloimmunization is a common phenomenon after transfusion, with an estimated incidence of 0.5% increasing to 20-60% in chronically transfused patients. In recently transfused patients, serological typing can be hampered by mixed field agglutination. We established RT-PCR methods for RHD, RHC/c and RHE/e typing using mRNA from reticulocytes. Molecular typing was performed soon after 51 separate mismatched transfusion events involving 30 patients. Accurate identification of the transfused patients' phenotype was confirmed in all cases. Reticulocyte maturation studies revealed that temperature is a crucial parameter for transition into mature red blood cells.