Anti-Jk3 in a Filipino man

A 62-year-old Filipino man with a history of chronic obstructive pulmonary disease, hypertension, and hyperlipidemia was admitted to the emergency department at Hospital A with recurrent fevers, weakness, and jaundice. The patient was evaluated and eventually discharged with a diagnosis of possible drug-induced hepatitis. One month later, the patient was admitted to Hospital B for recurrent fevers and weakness. The patient's hemoglobin was 3.8 g/dL. Six units of packed red blood cells (RBCs) were ordered for transfusion. The patient's sample typed as group B, D+, and the antibody screen was negative. All six units of packed RBCs appeared compatible (at immediate spin) and were transfused to the patient. His hemoglobin level 4 days post-transfusion was 9.3 g/dL, and the patient was discharged. The patient returned after a week for follow-up and his hemoglobin was found to have dropped to 8.5 g/dL, which continued to fall until it reached 7.0 g/dL. Additional packed RBCs were ordered for transfusion. During subsequent pre-transfusion compatibility testing, the antibody screen was found to be positive (all screening cells reactive at the antihuman globulin phase). An antibody identification panel was performed. The patient's serum was found to react with all panel cells tested, including the autocontrol tube. A direct antiglobulin test revealed the presence of both anti-IgG and anti-C3 coating the patient's RBCs. The specimen was then sent to a reference laboratory for further testing. Results from the reference lab testing revealed the presence of anti-Jk3 in the patient's serum. The patient was placed on steroids, and his reticulocyte count increased with no further signs of extravascular hemolysis. No additional transfusions were necessary. He was eventually discharged with a hemoglobin of 13.6 g/dL. The purpose of this case study is to report the findings of an extremely rare but clinically significant antibody, anti-Jk3.