Acute Hemolytic Transfusion Reaction Due to Anti-Kpa Antibody.

BACKGROUND: Kpa (KEL3, Penney) is a red blood cell antigen within the Kell system, first described in 1957, that occurs in less than 2 percent of the population. Although anti-Kpa antibodies were identified in 2-5 percent of those with alloantibodies among patients requiring chronic transfusion, only five previously published case reports of anti-Kpa reactions were identified.

CASE REPORT: Reported here is a case of an elderly female who experienced an acute hemolytic transfusion reaction due to this antigen. Following initiation of blood transfusion, she experienced a sudden onset of rigorous chills, accompanied by elevated temperature, tachycardia, and hypertension. Laboratory studies showed uremia, elevated creatinine, positive direct Coomb's, and low haptoglobin. Serology revealed anti-Kpa antibody.

CONCLUSION: This report is only the sixth, to our knowledge, of a significant reaction attributable to anti-Kpa and only the second of an acute hemolytic reaction associated with it. It serves as a reminder of the potential of low incidence antigens causing severe reactions; this potential should be considered when evaluating acute hemolytic reaction.