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

Anti-I^T 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-I^T 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-I^T. In both cases, the anti-I^T was a rarely encountered IgM warm reactive agglutinin; in one case, the IgG component was also anti-I^T, whereas in the second case the IgG antibody was broadly reactive. The unusual serologic finding of anti-I^T prompted further clinical evaluation for lymphoproliferative disease in these two patients. Immunohematology2009;25:60–62.