Characterization of three different rat T-cell clones with specificity to Listeria monocytogenes: phenotype, specific proliferation, lymphokine production, and protective capacity in vivo.

Splenic T lymphocytes from rats immunized with the facultative intracellular bacterium, Listeria monocytogenes, were cloned by the limiting-dilution technique. From several clones obtained, three have been scrutinized in detail. As demonstrated by their reactivity to the monoclonal antibodies, W3/25 and MRC OX8, the clones RVIIC2 and R23D6 are of helper cell phenotype, whereas cells from clone R30D5 express both the helper and the cytotoxic/suppressor cell markers. Proliferation of all three clones critically depends on antigen-presenting cells, exogenous interleukin 2, Listeria antigen, and on class II-restricted antigen presentation by accessory cells. There are differences between cells from different clones with respect to the degree of production of migration inhibitory and macrophage-activating factors. Thus, T lymphocytes of clones R23D6 and R30D5 are highly active, whereas cells of clone RVIIC2 showed markedly less production of these factors. In vivo studies, analyzing the capacity of cells to transfer systemic protection, showed a positive correlation between the production of migration inhibitory factor, macrophage-activating factor, and systemic protection.