Effects of triptonide on mouse immune functions.

Triptonide (Tri) extracted from Tripterygium wilfordii Hook inhibited the proliferation of mouse splenocytes induced by suboptimal concentration of concanavalin A or lipopolysaccharide at concentrations of 0.02, 0.1, and 0.5 microgram.ml-1. It showed a suppressive effect on one way mixed lymphocyte culture (MLC) at 0.1-0.4 microgram.ml-1. The lymphocytes harvested from the first Tri (0.4 microgram.ml-1)-containing MLC inhibited the second MLC after being washed and irradiated with 60Co source (30 Gy). Serum anti-sheep red blood cell antibody (hemolysin) formation and clearance of charcoal particles were also suppressed by Tri in vivo. Although delayed hypersensitivity (DH) reaction to dinitrofluorobenzene (DNFB) was inhibited by Tri 1.2, 2.5, and 5.0 mg.kg-1 (ip, qd x 5 d), the spleen cell interleukin-2 secretion activities of these mice were not suppressed. Graft vs host reaction (GVHR) was not inhibited by Tri 2.5 and 5.0 mg.kg-1 (ig, qd x 5 d). Helper T cells (Th)/suppressor T cells (Ts) ratio was reduced at 2.5 mg.kg-1. The effects of Tri on mouse thymus and spleen weight were related to the age. Tri (1.2, 2.5, 5.0 mg.kg-1) had no effect on thymus and spleen weights in 8-wk-old mice. However, it increased the thymus and spleen weights in 12-wk-old mice at doses of 1.2 and 2.5 mg.kg-1. The data indicated that Tri had extensive suppressive effects on mouse immune function and its mechanism may be related to the reduction of Th/Ts ratio and the induction of Ts cells.