[Recent findings on the mechanism of murine T-cell lymphomagenesis]

The pathogenesis of murine T-cell lymphomas, induced by radiation, chemical carcinogens or lymphomagenic retroviruses, implicates such multiple factors as the derangement of T-cell differentiation, intervention of the endogenous retroviruses, the expression of the cellular oncogenes, and so on. The application of virological, immunobiological and molecular biological techniques has opened an avenue to gaining an insight into the mechanism of the disease. Among recent achievements, data on the following aspects are presented in this review. 1) Unequivocal demonstration of the "indirect induction mechanism" of lymphoma using Thy. 1 congenic mice, 2) the presence of preleukemic cells and their evolution to leukemic cells by virtue of the thymic microenvironment, 3) search for the expression or rearrangement of v-onc and c-onc with molecular hybridization techniques, and 4) generation of lymphomagenic retrovirus from non-producer T-cell lymphoma cell lines infected with non-oncogenic endogenous ecotropic virus, which may represent the emergence of a lymphomagenic virus following leukemogenic treatments through the genetic recombination of viral genomes.