RBCs of Asian-type DEL do not undergo antibody-mediated phagocytosis by macrophages.

BACKGROUND: In the Rhesus (Rh) blood group system, D is the most immunogenic antigen. RhD-negative patients with anti-D must be transfused RhD-negative red blood cells (RBC) to avoid hemolytic transfusion. RBC of Asian-type DEL phenotype are typed as RhD-negative by routine blood group serological methods because they have very weak expression of D antigen. The prevalence of Asian-type DEL phenotypes was 30% in RhD-negative Chinese donors. Therefore, this DEL type can be transfused to RhD-negative patients with anti-D. However, there is a lack of direct evidence regarding the safety of this practice and potential mechanisms in act. MATERIALS AND METHODS: The proportion of Asian-type DEL donors that serologically tested RhD-negative was investigated by using genotyping. Furthermore, a model system for in vivo clearance was established to assess antibody-mediated phagocytosis of Asian-type DEL RBC by macrophages. RESULTS: We identified six serologically RhD-negative donors, 16 Asian-type DEL donors according to polymerase chain reaction polymerase chain reaction with sequence-specific primers (PCR-SSP), and six PCR-SSP RhD-positive donors across various regions in China. Our study revealed that antibody-mediated RBC clearance was not observed following co-culture of opsonized Asian-type DEL RBC with macrophages. DISCUSSION: Incompatible transfusion of Asian-type DEL RBC may not result in significant RBC clearance.