Characterization of immunomodulating action of TI-31 on antibody response in mice.

TI-31, at concentrations of 10 and 100 microM, suppressed the antibody response to T cell-dependent (sheep red blood cells, SRBC) and -independent antigens (trinitrophenyl-lipopolysaccharide, TNP-LPS and TNP-Ficoll). The anti-SRBC response was suppressed by TI-31 when T cells were replaced by a supernatant of concanavalin A (Con A)-stimulated spleen cells, indicating the drug had influence on T lymphocytes, B lymphocytes and macrophages. TI-31 augmented the Con A-induced suppressor T cell (Ts) assessed by anti-SRBC plaque-forming cells response in vitro. The drug (10 mg/kg, p.o.) potentiated antigen specific Ts induction in vitro after injection of a high dose of SRBC. The results demonstrate that TI-31 enhanced Ts induction, which resulted in a diminution of antibody formation.