Asian Journal of Immunology

Anti-N antibodies usually possess cold-reactive properties which make them clinically insignificant and are mostly classified as naturally occurring IgM antibodies. These antibodies sometimes trigger reactions at body temperature (37°C) or in the anti-human globulin phase resulting in serious medical outcomes such as delayed hemolytic transfusion reactions or hemolytic disease of the newborn. This case shows an extraordinary naturally occurring anti-N antibody which was detected in a 20-year-old male liver donor during standard antibody testing because of its unexpected reactivity at 37°C. The absence of any previous blood transfusions or medication use in the patient made this case stand out as particularly intriguing. The antibody identification was successful following the 'pre-warm' technique implementation while antigen phenotyping validated it as an IgG-type anti-N antibody. This medical case demonstrates the critical importance of recognizing unusual antibody responses during blood transfusions and organ transplants because uncommon reactions may lead to serious consequences.