Autoantibodies mimicking anti-Jkb plus anti-Jk3 associated with autoimmune hemolytic anemia in a primipara who delivered an unaffected infant.

A serum sample from a nontransfused 25-year-old Caucasian primipara contained weak anti-Jkb plus anti-Jk3. The direct antiglobulin test on the patient's red cells was strongly positive. Anti-Jkb was recovered in a heat eluate. An ether eluate contained anti-Jk3. Her red cells types as Jk(a-b+)Jk:3. The anti-Jkb and anti-Jk3 reactivity was completely absorbed both by red cell samples lacking and red cells possessing the corresponding antigens, indicating these antibody specificities to be of the mimicking variety. At 41 weeks gestation she delivered a normal, healthy infant with no detectable serum or cell bound antibody.