Anti-A and anti-B isohemagglutinins in the course of children's leukemias.

The changes in titres of isohemagglutinins anti-A and anti-B were followed up in 48 leukemic children during relapses and remissions. The levels of titres were compared 1. with levels in healthy children in the same age group, 2. in the different phases of disease in the same child. Compared with healthy children, a higher frequency of low isohemagglutinin levels was found in the phases of the exacerbation of malignancy, no changes were observed in remissions. In some children a quite evident fluctuation of isohemagglutinin titres in relation to the phases of the malignant disease was found. The depression of blood group isohemagglutinins in the phases of activation of the malignant process is considered as a partial defect in IgM, analogical to the so called normoglobulinemic defect of the antibodies.