Association of a possible DNA ligase deficiency with T-cell acute leukemia.

DNA ligase activities were determined in blood samples of 431 different cases of lymphoblastic and nonlymphoblastic leukemia. Less activity was observed in samples from lymphoblastic patients. RNA translation together with ligase immunoprecipitation experiments show that in T-cell acute lymphoblastic leukemic cells, no ligase is translated. This deficiency is correlated with the presence of more breaks in the DNA from these kinds of leukemia which results in altered DNA. This DNA can be ligated by the addition of exogenous ligase. This is the first demonstration of a ligase deficiency in leukemic human cells. These results are discussed in terms of chromosome abnormalities and rearrangements of genes coding for enzymes involved in DNA replication and repair.