Concentration dependency of cyclosporin and chloroquine as inhibitors of cell proliferation and immunoglobulin production upon mitogen stimulation of mononuclear cells.

The effects of the drugs cyclosporin (Cs) and chloroquine (Chl) on the pokeweed mitogen (PWM)-induced immunoglobulin (Ig) production of peripheral blood mononuclear cells (PBMC) of blood donors, were investigated. A significant inhibition of the Ig production was found at concentrations of 0.001-0.025 microgram Cs/ml and 0.1-2.5 microgram Chl/ml of culture medium respectively, while no effect was found on cell proliferation at these concentrations. The combination of various concentrations of Cs with a constant amount of Chl (0.5 microgram/ml) and various concentrations of Chl with a constant amount of Cs (0.005 microgram/ml culture medium), resulted in a reduction of the Ig content in supernatants which was not different from the calculated sum of the effects of the individual drugs at the respective concentrations. It was concluded that both drugs exerted an effect on the PWM-driven stimulation of PBMC, depending on the concentrations used, which might be of interest in the treatment of rheumatoid arthritis.