Abstract
During serial inoculation of spontaneous Iympbocytic leukemia in C58 and AKR mouse strains by splenic cell-free extracts, a change of the leukemia type from lymphocytic to myelogenous was observed. As a method to clarify this phenomenon, isolation of viruses by passaging through guinea pig brains and cross-neutralization tests of viruses according to the method of Hamazaki were performed with these two types of leukemias in both strains of mice. First of all, the author succeeded in isolating viruses of the, original lymphocytic leukemia and the changed myelogenous leukemia. These viruses induced a mesenchymal tissue reaction in the spleen, lungs and liver of the guinea pigs in serial passage. The pathological changes were especially prominent in the lungs and spleen; in the lungs so-called viral interalveolar pneumonia and granulomatous inflammation around the interstitium were observed, and in the spleen proliferation of the reticulum cells in the red pulp and of the sinus endothelium were seen. These chauges were slight in the liver and brain. A diffuse proliferation of the stellate cells in the liver and chickening of the pia mater and sometimes proliferation of the glia cells were observed.
