Comparative Activity of Isologous versus Homologous Mouse Bone Marrow on Lymphoid Tumor Production Following Irradiation. ∗

Summary

1. Lymphoid tumor development in irradiated C57BL mice was inhibited specifically by isologous marrow: homologous marrow, including F₁ hybrid marrow, was incapable of inhibiting the tumor process in C57BL mice after sublethal radiation exposures. 2. F₁ (C57BL x BALB) hybrid mice were protected against radiation-induced lymphomas by compatible marrow. The protection was essentially equal, whether the marrow injected was from F₁ hybrid or from either parental strain. The similarity between these results and those previously reported with respect to marrow-mediated thymic weight regeneration is discussed. Since host immune reactions to incompatible cells are not abolished at these radiation dose levels, it is inferred that these effects of marrow injection require persistent presence of viable marrow cells. 3. A number of lymphomas were tested for transplantability into various strains. Of those tested, none arising in C57BL mice injected with homologous marrow were found to be other than C57BL tumors, whereas 3 of 9 tumors which arose in F₁ hybrids despite marrow injections, grew in the parental marrow donor strain, indicating that repopulation must have occurred in these cases at least.