Enhanced AKR leukemogenesis by the dual tropic viruses. II. Effect on cell-mediated immune responses

We examined the relationship of the leukemia-accelerating properties of a dual-tropic virus (DTV-70) (when injected into the thymus of 14-day-old AKR mice) to its ability to impair T cell functions. Splenic lymphocytes from virus-infected AKR mice were found to have reduced T cell mitogenic responses; moreover, these cells suppressed phytohemagglutinin stimulation of cells from normal, uninfected AKR mice. The response to the B cell mitogen lipopolysaccharide was slightly enhanced at 15 days following DTV-70 infection and was unaffected at later ages. AKR mice infected with DTV-70 showed reduced ability to develop delayed-type hypersensitivity reaction and interleukin 2 production. In contrast, spleen cells from the virus-infected mice responded normally to allogeneic stimulation in mixed lymphocyte culture and mounted an almost normal graft versus host reaction. The data suggest that DTV-70 impairs certain T cell functions that could interfere with immune surveillance and thus permit progression of preleukemic cells into overt leukemia. These T cell functions are suppressed normally by 6 months of age, perhaps by spontaneously arising DTV.