A simple, practical model for reducing alloimmunization in patients with sickle cell disease

Abstract

Patients with sickle cell disease (SCD) form immune alloantibodies more frequently than other transfused populations because red cells (RBCs) from white donors (with a higher incidence of certain Rh, Duffy, Kell, and Kidd blood group antigens) are transfused to black patients often lacking these antigens. We propose a model to reduce alloimmunization in patients with SCD by providing them with blood from only black random donors. Rationale is shown by examining calculations based on the phenotype E-, C-, Fy(a-), K-, and Jk(b-). There is a 7% probability that this phenotype belongs to a white donor, while there is a 93% probability that this phenotype belongs to a black donor. The probability of selecting blood from a black donor identical with the above phenotype for black recipients from an all black population and from a typical urban blood inventory population (90% white, 10% black) is 1/4 and 1/33, respectively. Therefore, an 8-fold greater chance of selecting antigen non-identical blood occurs if blood is obtained from a typical urban donor population as compared to a black population. Based on these calculations, alloimmunization can be reduced prospectively in patients with SCD by meeting their transfusion requirements with blood selected from random black blood donors.

High prevalence of red blood cell alloimmunization in sickle cell disease despite transfusion from Rh-matched minority donors

“…Based on antigen prevalence differences, it was hypothesized that alloimmunization would be reduced in patients with SCD by transfusion with blood selected from ethnically similar donors. 34 Indeed, antibodies to FY, JK, and S were rare, with a rate of 0.027/100 units. However, the overall incidence of alloimmunization was higher than expected, primarily due to a large number of unexpected Rh antibodies.…”

Molecular biology of the Rh system: clinical considerations for transfusion in sickle cell disease

“…31 In addition to antigen-matching for D, C/c, E/e, and K antigens, a program to direct blood from African-American donors to children with SCD was initiated in 1997 as a cooperative effort between Children's Hospital of Philadelphia (CHOP), the Penn-Jersey American Red Cross, and the local Chapter of the Sickle Cell Disease Association of America. 26 Blood donors voluntarily selfidentify as African-American and agree to have their blood specifically support SCD children by selecting a special tag to attach to their donation.…”

Membrane Blood Group Antigens and Antibodies

“…Because the incidences of antigens differ in various ethnic groups, blood for these patients is most likely to be found among African American donors, whose RBCs more commonly lack C, E, K, S, Fy a , Fy b , and Jk b antigens than the RBCs of white donors. 70 However, it is worth noting that RBCs from African American donors are more likely (approximately 1 in 5) to express antigens for which we do not routinely test, such as VS, Js a , Go a , and DAK. 71 Thus, because all these antigens are immunogenic but are not present on screening cells, it is recommended in this group of patients that blood be crossmatched using the IAT in preference to performing a computer match.…”

“…63,64 There is still no consensus as to the best and most practical approach, although the goal is to provide blood with maximal survival. In addition to the traditional practice of providing antigen-negative blood only after the patient has made an antibody, approaches that have been adopted include providing phenotype-matched blood after the first antibody is made; providing blood matched for D, C, E, and K antigens; providing fully antigen-matched blood (i.e., matched for D, C, E, c, e, K, Fy a , Fy b , Jk a , and Jk b antigens); and providing blood based on ethnic background combined with antigen matching for D, C, E, and K. [65][66][67][68][69][70] Clearly, if the objective is to prevent immunization to blood group antigens, initial phenotype matching is the logical approach; however, this approach does not prevent the production of antibodies to high-prevalence antigens, such as U, Js b , Cr a , hr S , and hr B . The decision as to whether the blood donor community can support this approach lies with the directors of the transfusion service and of the donor center that supplies the blood.…”