Cell-Free Transmission of AKR Mouse Leukemia

1. Spontaneous mouse leukemia began to develop at 6 months and its maximum incidence was observed at 9 months of age.2. Of mice inoculated at less than 24 hours of age with cell-free filtrates extracted from AKR leukemic livers, spleens, and lymph nodes, 39.1% developed leukemia within 6 months. The incidence of leukemia for two groups of mice, 24 to 48 hours old and 48 to 72 hours old, was equally 25%. Very seldom leukemia resulted in mice inoculated at 6 to 48 days of age. There was a 2-month acceleration in the development of leukemia, however, in comparison with the control group.3. Whereas more females than males developed leukemia before 6 months following inoculation, after that time the reverse was the case.4. Leukemogenic activity of brain extracts was weaker than that of lymph node extracts.5. The second cell-free passage caused more leukemias than the first cell-free passage within 6 months.6. At autopsy there were two distinct types of leukemic involement, thymic and lymph node, and also transitional types of the two.7. The peripheral leukocyte count ranged in the majority of cases from 20, 000 to 30, 000per cu mm, rarely reaching 80, 000per cu mm. In differential counts, there were 1% to 52% lymphoblasts. Some leukemic mice showed an increase of cells of the neutrophilic series. Nucleated red cells were also present.8. In bone marrow, lymph node, thymus, and spleen, lymphoblasts were of the predominant cell type.9. In vitro tissue culture of lymph node, bone marrow, and spleen produced an identical growth pattern with that of acute lymphatic leukemia in human beings.10. The chromosomes studied in spontaneous AKR leukemia were 40 in number and rod-shaped, showing no aberrations from the normal counterparts.11. The first cell-free passage resulted in one of the mice in the development of myelogenous leukemia. The second cell-free passage from the myelogenous leukemia induced lymphatic leukemia in one of the mice injected.12. Lymphatic leukemia, once converted to the ascitic form, was subsequently maintained in the ascitic form by successive intraperitoneal transplantation.