Production of Listeria-specific rat T-cell clones and role of interleukin-2 receptors in regulation of Listeria-dependent T-cell clone growth in vitro.

Splenic T lymphocytes from rats immunized with the facultative intracellular bacterium Listeria monocytogenes were cloned by the limiting-dilution technique in the presence of accessory cells, heat-killed L. monocytogenes as antigen, and conditioned medium containing interleukin-2. The cloned rat T-cells were Listeria-specific cells, and their proliferation depended on class II-restricted antigen presentation by accessory cells. As demonstrated by their reactivity to the monoclonal antibody W3/25, the clones were of helper cell phenotype. Cloned-cell proliferation depended on repeated (or continuous) exposure to antigen. When antigen was omitted from the system, cell growth subsided over time, and cells finally ceased to grow. By the use of the monoclonal antibody ART-18, which recognizes the interleukin-2 receptor, it was shown that cessation of growth was accompanied by the disappearance of interleukin-2 receptors from the cell surface. The addition of antigen to the culture resulted in the reexpression of interleukin-2 receptors and concomitant resumption of proliferation.