Pathogenesis of Mouse Viral Leukemia. ∗

Abstract

Summary and conclusions

1. Incidence of thymic leukemia in AK/Z mice injected as newborns with Gross leukemia virus(agent A) was 90% and the peak incidence of the disease occurred at 3-4 months of age. Incidence of leukemia in the controls was 73% with a peak occurrence at 8-12 months. 2. Thymuses from 52 sacrificed virus-injected AK/Z mice were examined at 13-72 days of age. No gross or microscopic abnormality was noted until about SO days, when multiple foci of medium to large lymphocytes appeared in the cortex. These foci rapidly became confluent and at about 70 days of age, the thymus was transformed into a lymphomatous tumor. 3. Bioassays of 22, 57-74 day old thymuses from virus-injected mice disclosed autonomous leukemic cells in 10. Correlation of microscopic and bioassay diagnosis of malignant transformation was somewhat below 100%. Some thymuses, which were judged to be leukemic “in situ”, were not transplantable. 4. Bioassays indicate the presence of virus in non-leukemic thymuses of virus-injected mice. 5. It is concluded that the pathogenesis of virus-induced thymic lymphoma is similar to that of “spontaneous” lymphoma in the high leukemic strain but occurs at an earlier age.