Influence of Host Factors on Development and Type of Leukemia Induced in Mice by Graffi Virus23

Cell-free extracts of leukemic tissues containing the Graffi virus were serially transmitted to newborn mice of the AKR, XVII, C57BL, DBA/2, C3Hf/Gs, and Swiss strains. In all the strains tested, leukemia developed with an incidence of approximately 90 percent, after latent periods ranging from 13 to 20 weeks. Although Graffi virus has been described as myelogenous, different types of leukemia, i.e., lymphatic, stem-cell, and myeloid, occurred in the various strains. In AKR mice inoculation of the virus caused lymphatic leukemia almost exclusively, which appeared after a median latent period of 14 weeks. When cell-free extracts of AKR lymphatic leukemia were passed in other strains of mice, such as C57BL and DBA/2, myeloid forms appeared in a significant number of the recipients. Induction of leukemia by the Graffi virus was also studied in C3Hf/Gs and AKR mice whose spleen or thymus gland had been removed. Splenectomy did not modify the incidence and type of leukemia. However, 76 percent of the C3Hf/Gs mice and 40 percent of the AKR mice that had been thymectomized developed myeloid leukemia. In the shamoperated controls, 8 percent of the C3Hf/Gs and 3 percent of the AKR mice developed a similar lesion. It is concluded that the environmental conditions of the recipient hosts significantly influence the type of neoplastic response induced by the Graffi virus.