Erythrocyte Alloimmunization and Transfusion Strategies in Sickle Cell Disease: A Single-Center Analysis

Alloimmunization (the production of antibodies against foreign red blood cell (RBC) antigens) is a significant complication in patients with sickle cell disease (SCD) who require chronic transfusion. This retrospective study examined the distribution of ABO and Rh phenotypes in SCD patients at Dr. Soliman Fakeeh Hospital in Jeddah (DSFH-J) and their implications for alloimmunization risk. The high immunogenicity of the K antigen in the Kell system, second only to that of the D antigen in the Rh system, makes it a frequent target.

Among 241 patients with SCD, the most common blood group was O (58.5%), followed by A (26.97%), B (12.03%), and AB (2.9%). The majority of patients (93.36%) were Rh-positive (D antigen-present). Among Rh antigens, the e antigen was the most prevalent (97.51%), while C antigen and c antigen were detected in 68.04% and 75.52% of patients, respectively. Within the Kell system, K was found in 8.29% of the study population. The most common antibodies detected were anti-E (20%) and anti-C (15%), indicating Rh incompatibilities to be a major concern. Kell system antibodies (anti-K) accounted for 12.5% of cases, and unidentified alloantibodies represented 17.5%. Although antibodies from other blood group systems (such as Kidd, Duffy, Lutheran, and MNS) were detected at low frequencies, their presence and known clinical significance in causing transfusion reactions underscore the need for extended RBC phenotyping to include these systems.

The observed distribution of Rh phenotypes and the presence of alloantibodies beyond the prevalent ones highlights the need for extended RBC phenotyping to include other blood group systems, such as Kidd and Duffy. Establishing a national blood donor registry with comprehensive RBC antigen data is a crucial step toward ensuring safer transfusions. Standardizing blood screening protocols across hospitals in Saudi Arabia and introducing routine extended RBC typing before transfusions would minimize alloimmunization risks and improve the overall patient safety.