Detection of IgG anti-A/B must be essential for safe transfusion support in patients undergoing ABO incompatible allogeneic HSCT

Recipients of ABO incompatible allogeneic HSCT present with unusual ABO groups and crossmatch problems accompanied by change of the ABO group from that of the host to the donor. We report on a patient undergoing major ABO incompatible allogeneic HSCT (donor/recipient: A/O) whose blood group was wrongly established to have completely switched to blood group A when using a routine tube method and micro gel column blood grouping card on the 68th day post transplantation. The major crossmatch test with added antiglobulin and blood group A red cells was still positive. After further investigation, an explanation was found because we could not detect IgG anti-A in the serum. At the same time, anti-A coated the patient’s RBCs and could be identified using a heat elution method although the DAT was negative. We also found an obvious mixed field with the LISS-IAT gel card. Hence, routine methods of ABO grouping are unfit for ABO incompatible allogeneic HSCT patients and a micro column neutral gel card is recommended for forward typing especially to detect mixed fields and a LISS-IAT gel card or IAT tube method for detecting IgG anti-A/B in reverse typing.