Naturally occurring anti-Kp^a in an infant with recurrent bacterial infection: A case report and review of the literature

Naturally occurring anti-Kp^a antibody is extremely rare and was first reported in 1957, named after the first producer ‘Penney’. However, the subsequent anti-Kp^a reports presented were all anti-Kp^a due to isoimmunization. Individuals with severe bacterial infections particularly Gram-negative bacteria are known to be capable of producing cross-reactive antibodies against Kell blood group system. However, such uncommon antibodies like anti-Kp^a can be easily missed in routine pre-transfusion testing unless the panel cells containing low incidence antigen are used for antibody screening. Here, we report a case of naturally occurring anti-Kp^a antibody, identified incidentally during pre-transfusion testing of a 12-month-old female infant with the diagnosis of Niemann–Pick disease and recurrent bacterial (Escherichia coli) infection.