Clinical evaluation for lymphoproliferative disease prompted by finding of IgM warm autoanti-IT in two cases

Anti-IT is an unusual specificity originally described as a naturally occurring cold agglutinin. The antibody reacts strongly with cord RBCs, weakly with adult I RBCs, and most weakly with the rare adult i RBCs. IgG anti-IT in patients with hemolytic anemia has been associated with Hodgkin's lymphoma. Difficulties in blood grouping tests and the presence of a warm reactive agglutinin in samples from two patients with hemolytic anemia led to further serologic studies and the identification of anti-IT. In both cases, the anti-IT was a rarely encountered IgM warm reactive agglutinin; in one case, the IgG component was also anti-IT, whereas in the second case the IgG antibody was broadly reactive. The unusual serologic finding of anti-IT prompted further clinical evaluation for lymphoproliferative disease in these two patients.