Leukemia Virus-Induced Immunosuppression

Abstract

Abstract Spleen cells from mice infected with Friend leukemia virus lost their capacity to migrate in vitro as assessed by the capillary tube culture procedure used to demonstrate cellular immunity. Spleen, lymph node, thymus and bone marrow cells from normal non-infected mice readily migrated in vitro. A marked inhibition of spleen cell migration occurred when the donor mice were infected with FLV 5 to 7 days or more before culture. Less or no suppression occurred when mice had been infected for less than 5 days. Normal migration was evident with spleen cells from mice infected on the day of testing or one day earlier. Loss of lymphoid cell migration activity was directly related to the dose of virus used for infection: a smaller dose resulted in less pronounced inhibition. Furthermore, lymph node, thymus and bone marrow cells were less affected than were spleen cells. Superficial and deep lymph node cells and bone marrow cells lost migration activity 2 to 3 weeks after infection, whereas thymus cells were unaffected until the 4th week of infection. No migration-inhibitory factor could be detected in culture supernatants of spleen cells from FLV-infected animals sensitized with an allogeneic skin graft or tubercle bacilli and challenged in vitro with the appropriate antigen. In contrast, similar cultures of lymphoid cells from sensitized control mice released an inhibitory factor as assessed by inhibition of migration of normal spleen cells in vitro, when incubated with the appropriate antigen. These observations indicate that a normal functional capacity of lymphoid cells of mice, i.e., migration in vitro of macrophages and other motile cells, is rapidly inhibited by in vivo infection with a leukemia virus. The relationship between such inhibition and cellular immunity in leukemic mice was discussed.