The relative importance of the oligosaccharide units in human chorionic gonadotropin (CG) for LH/CG receptor activation in rat Leydig cells and mouse Leydig tumor cells.

The biological properties of deglycosylated human chorionic gonadotropin (DhCG), obtained by hydrogen fluoride treatment (HF-DhCG) of intact hCG or by oligonucleotide-directed mutagenesis (CHO-DhCG), and that of their fully glycosylated counterparts, were tested in terms of cAMP and steroid production in rat Leydig cells and in mouse Leydig tumor cells (MA-10 cells). In both cell types, HF-DhCG and CHO-DhCG possessed comparable biological activities. The maximum for DhCG-induced cAMP production was approximately 12% of that of intact hCG when tested in rat Leydig cells, and only 2% when tested in MA-10 cells. DhCG possessed significant steroidogenic activity in both cell types. In MA-10 cells the maximum for DhCG-induced steroidogenesis was 30-50% of that of intact hCG, while in rat Leydig cells DhCG and hCG induced similar steroidogenic maxima. Based on its ED50, DhCG possessed 10-17% of the steroidogenic potency of intact hCG in rat Leydig cells, while in MA-10 cells DhCG was only 2-fold less potent than hCG. When accurate hormone-receptor binding data are absent, the intrinsic receptor-stimulating activity of a ligand can still be estimated at full receptor occupancy, provided that over the whole dose range the biological response is proportional to receptor stimulation. The present data show that in transfected MA-10(P+29) cells which over-express rat phosphodiesterase, the hormone-induced stimulation of cAMP and steroid production is directly coupled to receptor activation up to maximal occupation of the LH/CG receptor.(ABSTRACT TRUNCATED AT 250 WORDS)

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.