Anti-Jk3 with no clinical evidence of HDN

A sample was submitted to a reference lab from a 27-year-old Asian female, gravida 4 para 1, for antibody identification. Anti-Jk3 with an IgM component was identified. Subsequently, the antibody was eluted from the infant's cord and venous red blood cells. Normal bilirubin and hematocrit levels ruled out hemolytic disease of the newborn (HDN). Anti-Jk3 has been implicated in two cases of mild HDN. In this case, this noncomplement-binding antibody caused a positive direct Coombs test without clinical signs of HDN.