Department of Pathology, Indiana University School of Medicine, Indianapolis, IN Indianapolis, Indiana, United States
Background/Case Studies: Anti-U was identified by Wiener et al. in 1953 and is clinically significant due to its association with hemolytic transfusion reactions. The U antigen is prevalent on red blood cells, found on the surface of approximately 99% of Black individuals and nearly 100% of Caucasian individuals. Patients who lack the U antigen (U-negative) with rare exception also lack the S and s antigens have the potential to produce anti-U antibodies that can target the U antigen regardless of the S and s status. In contrast, studies have reported that approximately half of S-s− individuals exhibit the U+ phenotype. However, in these cases, the U antigen undergoes molecular alterations and is denoted by the term U+var. People with the S-s−U+var phenotype produce anti-U antibodies that react with both U+ and a variable proportion of other U+var cells. We present a rare case of the development of anti-U antibodies in a patient with Hemoglobin SS, sickle cell disease (SCD).
Study
Design/Methods: Review of patient history, transfusion history, routine screening to include a type/screen, antibody identification workup, and molecular antigen phenotyping.
Results/Findings: We present a female in the second decade of life with a history of SCD undergoing laparoscopic cholecystectomy. Preoperative transfusion was requested for optimization of hemoglobin and hydration. The patient’s blood type is A, Rh positive, and immunohematological workup revealed warm autoantibody with positive eluate and a new anti-U antibody. Additionally, molecular antigen phenotyping showed negativity for C, E, K, Kpa, Jsa, Jkb, S, s, Lua, and U+var. Preoperative transfusion with two units of leukoreduced HbS negative red blood cells S-s- was without complications. Conclusions: We addressed the challenge posed by the patient’s specific requirements for a blood unit that is U negative, matched for K, Rh-negative, and Hb S negative, and that blood bank should be promptly notified to facilitate the recruitment of a suitable unit. The complex antibody workup for this patient, particularly in the context of SCD, warranted special attention. The patient’s potential risk of acquiring more future transfusions further complicated the search for a compatible unit. Minimizing unnecessary exposure to blood products remains crucial to prevent alloimmunization and transfusion reactions in this patient population. However, situations like the one we presented, where surgical optimization is essential, make limiting blood product exposure challenging. When selecting red blood cell products for transfusion,The American Society of Hematology advocates for comprehensive matching beyond the ABO and Rh systems, including Jka/Jkb, Fya/Fyb, M/N, and S/s, for all SCD patients. In order to protect patients with challenging phenotypes from alloimmunization further testing including monocyte monolayer assay or donor genotyping needs to be considered for future transfusion.
