Vaccination against the intracellular bacterium Listeria monocytogenes with a clonotypic antiserum.

The T cell clone 26.1.1, which confers specific protection against the intracellular bacterium Listeria monocytogenes, was fused to BW 5147. The resulting T cell hybridoma, TLm1, could be stimulated to secret interleukin 2 by antigen plus accessory cells or concanavalin A. Stimulation was specific for an epitope expressed by L. monocytogenes EGD but not ATCC 19114 and was H-2I-A restricted. Antisera against TLm1 were raised in syngeneic mice and tested for their capacity to block TLm1 responses. Two antisera were identified that blocked antigen but not concanavalin A stimulation of TLm1 and did not affect antigen stimulation of similar but not identical L. monocytogenes-specific T cell hybridomas. Hence, these antisera had clonotypic activity. When these antisera were administered subcutaneously in complete Freund's adjuvant, mice were protected against a subsequent L. monocytogenes infection. Protection was antigen specific and H-2 nonrestricted. These findings suggest the feasibility of clonotypic antibodies for vaccination against intracellular bacterial infections.