Regulatory Mechanism of Delayed‐Type Hypersensitivity in Mice: IV. Effect of Suppressor T Cells on the Development of Memory T Cells Involved in Accelerated Generation of DTH‐Effector Cells In Vitro

The effect of suppressor T cells (Ts) on the induction and the subsequent development of memory T cells for delayed‐type hypersensitivity (DTH) was examined. The memory cells were induced in the spleens of mice primed previously with a low dose of reduced and alkylated ovalbumin (RA‐OA), and they generated DTH‐effector T cells (DTH‐Te) in a significantly accelerated fashion when cultured with OA in vitro . Ts were obtained from the spleens of mice which received OA‐coupled spleen cells i.v. 4 days previously, and they inhibited antigen‐specifically the induction of DTH responses in the recipient mice sensitized with alum‐absorbed OA only when transferred within 5 weeks before sensitization. The spleen cells from mice given Ts together with the priming antigen 7 weeks before culture failed to generate DTH‐Te in an accelerated manner on restimulation with OA in vitro . The memory cells from primed mice also did not cause accelerated generation of DTH‐Te, when cultured with Ts in the presence of OA in vitro . These results indicate that both the induction of the memory cells by priming with antigen in vivo and the subsequent development of memory cells to DTH‐Te by restimulation in vitro are inhibited independently by Ts. This corresponded well with the effect of Ts on the development of DTH‐memory in vivo .