Selective thymic localization of murine leukemia virus-related antigens in C57BL-Ka mice after inoculation with radiation virus.

The tissue distribution and extent of virus-specific antigen expression were studied by immunofluorescence as a function of time and of lymphoma development in adult C57BL/Ka (Fv-1(b)) mice after intravenous injection of radiation leukemia virus, a B-tropic murine leukemia virus. Viral antigens were detected earlier in the thymus (1 week) than in the bone marrow, spleen, or lymph nodes (2-3 weeks). Despite an initial virus-induced thymic involution, the percentage of immunofluorescence-positive cells in the thymus rapidly increased thereafter to 65-80%, at which level it remained until 9 weeks, at which time increases in size and weight, histological changes, and an increased number of blastoid cells indicated the onset of lymphoma development in the thymus. In contrast, the percentage of immunofluorescence-positive cells in the bone marrow, spleen, and nodes remained low, and gradually decreased to zero within 8 weeks after thymectomy. The selective thymic localization of antigens induced by radiation leukemia virus in C57BL/Ka mice is in striking contrast to the previously reported ubiquitous tissue distribution of the Gross-AKR virus, an N-tropic virus, in its natural host, the Fv-1(n), AKR strain with a high incidence of leukemia.