Effects of 4-[4''-(2'',2'',6'',6''-tetramethyl-1''-piperidinyloxy)amino]-4'-demethylepipodophyllotoxin on immune function in mice.

4-[4''-(2'',2'',6'',6''-Tetramethyl-1''-piperidinyloxy)amino]-4'-demethylepipodophyllotoxin (GP-7) 10-40 mg.kg-1 ip daily for 7 d reduced the specific antibody formation of splenocytes, serum agglutinin titer, and hemolysin HC50 in mice immunized with SRBC. GP-7 inhibited the footpad delayed hypersensitivity reaction and decreased the weights of spleen and thymus, but did not affect the phagocytic function of the peritoneal macrophages. In vitro the proliferation of mouse splenic lymphocytes activated by Con A was markedly inhibited by GP-7 in a concentration- dependent manner. At concentrations of 0.05-5 mg.L-1, the inhibition rates were 24-96%. These results suggested that GP-7 was an immunosuppressive agent.