Chromosome Conditions of Hypodiploid Moloney Virus-Induced Mouse Leukemia, Its Transplantability and Inductivity

Summary

Moloney virus-induced leukemia of BALB/c mice became transplantable in adult C3H mice after 2 successive transplant generations in suckling mice of the same strain. Cells with 39 chromosomes served as a stemline for the growth of the transplantable leukemias in the C3H mice. Thirty-nine mice were examined from the third through the sixteenth transplant generation, and a high percentage of the cells derived from their thymuses, spleens, and mesenteric lymph nodes, and livers showed predominantly 39 acrocentric chromosomes. Karyotype analyses revealed a depletion of 1 chromosome from the 40-chromosome complement of the control tissues. In 14 isologous whole-cell transplantations in C3H mice, 77% of 203 recipient hosts developed leukemias. Homologous transplantations of these leukemic cells in adult mice of the BALB/c, DBA, Rlll, and Swiss strains were negative. Only newborn Swiss mice developed the disease, and cells from their leukemic tissues showed 39 chromosomes. Evidence was presented that the transplantable leukemic cells contained virus; these cell-free extracts from the leukemic tissues of BALB/c mice of the second transplant generation induced the disease in Swiss mice inoculated at birth. The incidence of tumor growth was 92% (12/13), and the latent period, ranging from 9–30 weeks, averaged 16 weeks. In spleen cells of the cell-free, extract-induced leukemias of Swiss mice, the modal number of chromosomes was 40–41.