T cell proliferation in Mycobacterium lepraemurium infection. II. Characterization of cells that transfer resistance in subcutaneously infected mice.

T lymphocyte proliferation, Lyt phenotypes and their role in the evolution of protective immunity were studied in BALB/c and C57BL/6 mice infected subcutaneously with Mycobacterium lepraemurium. Antigen-induced proliferation was not demonstrable with T-enriched cells obtained from the spleens. However, these cells were capable of spontaneously proliferating in the absence of added antigen for a limited period. This proliferation was dependent on the presence of a phagocytic and adherent accessory cell. During the period when the T cells proliferated spontaneously they consisted of a mixture of Lyt-1 and Lyt-23 and were able to transfer protection to syngeneic recipient mice. Furthermore, the multiplication of the organisms was curbed during the same period demonstrating a strong association between the ability to proliferate spontaneously Lyt-1/Lyt-23 cells and protective immunity. T cells from normal BALB/c mice showed a marked suppressive effect on protection suggesting that these cells may be responsible for the susceptibility of this strain to a moderate subcutaneous infection.