An algorithm to locate hrB- donors for individuals with sickle cell disease

Many African Americans with sickle cell disease (SCD) develop alloantibodies to antigens in the Rh blood group system. Others have shown that from D- individuals, those lacking the high-incidence hrB antigen (> 98% prevalence) may be found among r'r African Americans. We describe an algorithm to locate units for African Americans with SCD and anti-hrB and -D. From 46,539 donations, 5136 listed African American as race. Our primary reference laboratory performed Rh phenotyping (D, C, c, E, e) for first-time donors and those not tested previously. Specimens typing r'r were sent to a secondary reference laboratory for hrB phenotyping after each donation. Hemoglobin S screening was performed. Of 24 donors (27 donations) who phenotyped r'r, seven donors,29.2 percent (nine donations) were hrB-. Two of seven who donated twice consistently tested hrB-. One of 24 donors initially tested hrB-, but hrB+ on repeat donation. The donor tested hrB- by a second reference laboratory. Reagents for phenotyping high-incidence antigens are often not readily available, requiring a specialized reference laboratory that adds cost and turnaround time. Our algorithm selected r'r African American donors most likely to lack hrB for further evaluation by a second reference laboratory. We felt this was the most judicious use of resources and provided the greatest opportunity to find compatible components for individuals with SCD and anti-hrB and -D.