Primary immune response to blood group antigens in burned children.

Delayed hemolytic transfusion reactions (DHTRs) are generally attributed to an anamnestic immune response. Case reports of DHTRs due to a primary immune response are rare. Transfusion reactions occurring in patients on the pediatric burn unit from 1981 to September 1988 were reviewed, and additional information was obtained for patients for whom a DHTR was documented. Of 62 transfusion reactions, 11 were classified as a primary immune response (DHTR), with either a positive antibody screen, a positive direct antiglobulin test (DAT), or both. None of the 11 patients included in the study had been previously tranfused or pregnant. The average number of units transfused prior to antibody identification was 19. The average time elapsed between the first transfusion and antibody identification was 3.6 weeks. Anti-K and anti-E were the most frequently identified. Three patients had a decrease in hemoglobin (average 1.5 g/dL) and hematocrit at the time that a positive DAT was detected. Such changes could not be demonstrated for the remaining eight patients. The conclusion was that a DHTR may he caused by a primary immune response in burned children more often than expected, but DHTR signs and symptoms are often not apparent due to the complications of burn trauma.