Distinguishing patients with suspected auto- versus allo-anti-Jka antibodies and highlighting the clinical significance: A case series from India.

Alloantibodies against Kidd (JK) blood group antigens are well known for their clinical significance due to their association with transfusion reactions and hemolytic disease of the newborn. In contrast, auto-anti-Jk antibodies are extremely rare and can pose significant diagnostic uncertainty. Moreover, distinguishing autoantibodies from alloantibodies remains a diagnostic challenge in transfusion-dependent patients. In this series we report three pediatric cases with hematological disorders in whom auto-anti-Jka were detected. On serological investigations, antibody detection and direct antiglobulin tests were positive in all three cases. The result of antibody identification was consistent with anti-Jka specificity. Molecular typing showed that all three patients had the JK*01/JK*01 genotype, which confirmed that the antibodies were autoimmune. In addition to auto-anti-Jka, one case involved an underlying anti-Fyb alloantibody, further complicating transfusion management. Despite these laboratory findings, none of the patients received any corticosteroids or experienced clinically significant hemolysis during the long-term follow-up. Transfusions were successfully managed using corresponding antigen-negative red blood cell units tailored to the antibody profiles. This case series underscores the practical value of red cell genotyping in resolving complex serological findings, and a cautious, individualized approach with close clinical and laboratory monitoring may be appropriate in the management of such cases. Our data contributes to the existing limited literature on the clinical behavior of auto-Jk antibodies.