Further observations on the effects of 1-thiocarbamoyl-2-imidazolidinone (TCI) on cell-mediated immunity.

1-Thiocarbamoyl-2-imidazolidinone (TCI) affected several cell-mediated immune responses, including two under suppressor control. In the cutaneous delayed hypersensitivity reaction of C57BL/6J (B6) mice to 2,4-dinitro-1-fluorobenzene (DNFB). TCI produced different effects depending on when it was given relative to hapten sensitization and challenge. When given 2 days before initial sensitization, TCI (10(-9)g/kg) caused inhibition of the 24 hr ear swelling response elicited 5 days after sensitization and slight enhancement of the response elicited at 10 days. Given 2 days after sensitization, the same dose of TCI produced little effect on the day 5 elicited response but appreciable enhancement of the day 10 elicited reaction. At doses of 10(-4) to 10(-1)g/kg, TCI given to B6 mice 1 day before tolerogen decreased 2,4-dinitrobenzenesulfonic acid sodium salt (DNB SO 3NA)-induced tolerance to DNFB sensitization initiated 10 days later. In vitro, TCI at concentrations of 10(-12), 10(-12) to 10(-3), and 10(-9) to 10(-1) g/liter was demonstrated to suppress, respectively, concanavalin A (Con A)-stimulated proliferation of B6 mouse spleen cells, the one way mixed lymphocyte reaction between mitomycin-inactivated AKR mouse spleen stimulator cells and B6 mouse spleen responder cells, and the generation of cytotoxic B6 spleen cells directed against 51Cr-labeled Con A splenic lymphoblasts from AKR mice. The results indicate that TCI can affect immunological reactions under suppressor control and mimic the immunosuppressive effects of either niridazole itself in vivo or immunoactive niridazole metabolite preparations in vitro.