Single allelic C mu gene rearrangements in patients with T cell and undifferentiated leukemia

By using a panel of monoclonal antibodies in combination with conventional morphological and histochemical studies, seven leukemic patients were diagnosed as having T-cell lymphocytic leukemia (ALL) and three patients were classified as having acute undifferentiated leukemia (AUL). When genomic DNA from each patient was analysed by the Southern blot hybridization technique, two out of seven cases with T-cell ALL and two of three cases with AUL demonstrated immunoglobulin (Ig) mu gene rearrangements. Interestingly, the patterns of C mu gene rearrangement found in these four cases as well as in the T-cell line HSB-2 were quite similar with rearrangement of a single allele and germ line configuration retained in the other allele. Ig gene rearrangement is an essential property of cells of B-lineage, but detection of an Ig gene rearrangement by itself seems insufficient to assign commitment to B-lineage differentiation. The significance of Ig gene rearrangements in T-cell ALL is unclear, but this heterogeneity at the DNA level among T-cell ALL may reflect differences in leukemogeneis and have prognostic and therapeutic implications.