Effective antibacterial protection induced by a Listeria monocytogenes-specific T cell clone and its lymphokines

The capacity of the murine Listeria monocytogenes-specific T cell clone 9-36-1 and of lymphokines derived therefrom to induce antibacterial protection in vivo was studied. Clone 9-36-1 was stimulated to proliferate and to produce lymphokines by in vitro culture with syngeneic accessory cells and heat-killed L. monocytogenes. Although 9-36-1 cells were highly active in vitro, intravenous transfer of the cells resulted in marginal protection against a systemic infection with L. monocytogenes. In contrast, 9-36-1 cells injected subcutaneously together with L. monocytogenes into the footpad induced marked protection in syngeneic, but not in allogeneic, mice. Multiplication of Salmonella typhimurium was not reduced by the T cell clone. Studies with 51Cr-labeled T cells indicated that the low activity of intravenously transferred cells was due to an altered migration pattern. Lymphokines produced by 9-36-1 cells in vitro induced protection against L. monocytogenes in syngeneic recipient mice. Lymphokine-induced protection was also demonstrable in allogeneic recipients and against S. typhimurium. These findings suggest that the L. monocytogenes-specific T cell clone 9-36-1, although unable to immigrate into sites of bacterial deposition, had retained its ability to mobilize antibacterial defense mechanisms once present at the site of reaction.