The transfusion of non-prophylactically RH-KEL1 antigen-matched red blood cells is feasible in selected myelodysplastic syndrome and acute myeloid leukaemia patients

Background and Objectives Most myelodysplastic syndromes (MDS) patients become red blood cell (RBC) transfusion-dependent. Transfusing MDS patients with prophylactically RH-KEL1 antigen-matched (PAM) RBC units is recommended to avoid RBC allo-immunization. D+C-E-c+e+, D+C-E+c+e- and D+C+E-c-e+ phenotypes are infrequent among French blood donors. To preserve infrequent phenotype RBC units for patients other than MDS, and to manage frequent phenotype RBC unit stocks, we let, for 1 year, higher-risk non-immunized chronically transfused MDS and acute myeloid leukaemia (AML) patients receive RBC transfusions matched only for D. Our objectives were to evaluate the impact of non-PAM transfusions on the transfusion policy (which would be modified in case of RBC allo-immunization) for frequent and infrequent phenotypes patients and to estimate the number of infrequent phenotypes RBC units that could be redistributed to other patients. Results Ninety patients were enrolled. Thirty-five patients had infrequent phenotypes, nine received only PAM RBC (143 units) and 26 PAM and non-PAM RBC (415 and 532, respectively): none developed allo-immunization. Fifty-five patients had frequent RBC phenotypes, 34 received only PAM RBC (561 units) and three developed antibodies (2 non-RH-KEL1 and one anti-E); 21 received PAM and non-PAM RBC (436 and 109, respectively) and one developed allo-immunization (unknown specificity). Our strategy enabled us to preserve 532 infrequent phenotypes RBC units: 216 D+C-E-c+e+, 33 D+C-E+c+e- and 283 D+C+E-c-e+ units, representing 48.8% of the total number of RBC units received by infrequent phenotypes patients during the study period. Conclusion Allowing the transfusion of non-PAM RBC in selected chronically transfused MDS and AML patients was feasible and enabled to redistribute infrequent phenotypes RBC units to other patients in need.