Dynamics of lymphocytic subpopulations in Friend leukemia virus-induced leukemia

The in vivo roles of the immunosurveillance mechanism of the host against leukemia induced by Friend leukemia virus (FLV) were examined. The significance of T-cells in host defense against FLV-induced leukemia was indicated by the fact that thymus-deprived C57BL/6N-nu/nu mice were sensitive to FLV, although normal C57BL/6N mice were, as already reported by many authors, resistant to FLV. In relation to the role of T-cells on the onset of FLV-induced leukemia, the population dynamics of the lymphocytic subpopulations of the systemic lymphoid organs after FLV injection in FLV-resistant C57BL/6N mice were examined in comparison with the dynamics in FLV-sensitive strains, C57BL/6N-nu/nu mice and normal C3H/HeN mice. In this system, Lyt-1+2- helper T-cells in the spleen of FLV-resistant C57BL/6N mice increased in number after FLV injection. The number of immunoglobulin positive cells did not remarkably change in FLV-resistant C57BL/6N mice after FLV injection, whereas the number increased in the lymph node of FLV-sensitive C3H/HeN mice. The results indicated that a major contribution to the relative susceptibility and resistance of the host to FLV was controlled by the capacity to mobilize T-cells to the spleen in an early stage of disease, although the interaction of these T-cells with other immune cells may play an important role in mediating host resistance to FLV-induced disease.