The role of bone marrow and thymic elements in the initiation and spread of virus production in the AKR thymus.

Passive anti-viral immunotherapy greatly suppresses the incidence of spontaneous leukemia in AKR mice, rendering the thymus of successfully treated animals devoid of infectious ecotropic retrovirus. Reconstitution assays have determined that the thymic and splenic homing cells of the AKR bone marrow become ecotropic virus producers subsequent to their seeding of these hematopoietic organs and that in vitro depletion of gp71 expressing bone marrow cells reduces stem cell numbers without affecting prothymocyte content. In the thymus, a population of radioresistant cells, which phenotypically resemble cortical thymocytes, but are unique in their expression of high levels of H-2Kk antigen, have been found to produce high levels of both ecotropic and MCF virus and have been implicated as a putative therapeutic target cell population of anti-viral treatment. In addition, the failure of treated animals to reconstitute following lethal irradiation suggests that an immunotherapy-induced alteration occurs in the bone marrow of AKR mice.