Extended, Flexible Program Matching Red Cell Antigens for Patients with Sickle Cell Anemia Provides for Both Chronic and Intermittent Transfusions.

Introduction: Transfusion of packed red cells (PRBCs) remains the major treatment of severe complications in sickle cell anemia. Patients may require acute, intermittent transfusions for some problems while other, more severe complications are treated with chronic transfusion (≥ 6 months) regimens to replace and suppress production of sickle cells. One of the main complications of transfusion therapy is production of red cell alloantibodies which significantly increases the risk of subsequent transfusions and limits the timely provision of appropriate blood products. Since 1978, we have provided sickle cell patients with extended matching of PRBCs to reduce the rate of alloimmunization. The flexibility of the program is adapted to meet both acute and chronic needs of the patient population.

Methods: Records of patients with sickle hemoglobinopathies enrolled in the Colorado Sickle Cell Treatment and Research Center between December 31, 1993 and January 1, 2006 were reviewed under a protocol approved by the COMIRB at UCDHSC. At enrollment, serologic testing was completed on patients for the following blood group antigens: ABO; Rhesus (C,c,D,E,e); Kell (K,k); Duffy (Fy^a,Fy^b); Kidd (Jk^a,Jk^b); Lewis (Le^a,Le^b); and MNS (M,N,S,s). Donors were typed for the same antigens. For all transfusions, a perfect match was sought. When exact matches at all loci could not be found, mismatches were allowed when necessary for Fy^b and MNS because of lower risk of sensitization and for Le because of infrequent hemolytic transfusion reactions. Antibody screens were completed as part of crossmatch technique at the time of each transfusion by standard methods. When an antibody screen was positive, standard antiglobulin and enzyme techniques and cell panels were used to identify the antibody. For the purposes of this study, information about patients with sickle cell anemia, complications, numbers and types of transfusions were reviewed.

Results: Over the past 13 years, a total of 6,978 transfusions were provided to 104 patients (mean 68, range 1–519). In this group, 90 patients (86.5%) had HbSS, 11 (10.6%) had HbSC, and 3 (2.9%) had HbS β-thalassemia. Indications for transfusions included vaso-occlusive crisis, aplastic crises, splenic sequestration, and preparation for surgery, acute chest syndrome, stroke and priapism. Fifty-two patients (50%) received simple transfusions only while 33 (32%) had only PRBC exchange and 19 (18%) required both modalities. Of the total group, 42 (40%) were on chronic transfusions and 11 (10%) had both intermittent and chronic transfusions. The protocol and system for delivering matched PRBCs was flexible enough that even when red cells were needed for intermittent transfusions in 62 (60%) patients, delivery of the products was easily accomplished. In only 8 patients receiving 13 units of PRBCs was the clinical situation so urgent that non-antigen matched units was required.

Conclusion: PRBCs with extended antigen matching were provided to our population of patients with sickle cell anemia. The program provided blood components for both intermittent and chronic transfusion schemes with very few patients having such urgent conditions that they required products without extended matching.