Selective inhibition of T-cell-dependent immune responses by bisbenzylisoquinoline alkaloids in vivo.

The bisbenzylisoquinoline (BBI) alkaloids, chondocurine, tetrandrine, isotetrandrine and cepharanthine, were tested for immunosuppressive activity in mice. A plaque-forming cell (PFC) response to a T-cell-dependent antigen, sheep red blood cell, was significantly suppressed by a 7 day treatment of chondocurine or tetrandrine at 1 mg/kg/day and of isotetrandrine at 50 mg/kg/day, but not suppressed by cepharanthine treatment. The suppressive effect of chondocurine was greater when it was given after immunization rather than before or concurrently. However, it did not affect the PFC response to a T-cell-independent antigen, lipopolysaccharide. A delayed-type hypersensitivity was also suppressed by chondocurine treatment. There was no significant change in lymphocyte number and proportion of T-cell subsets in the BBI alkaloid-treated mice. These data suggest that there is selective inhibition by chondocurine and tetrandrine of the T-cell-dependent immune reactions.