Effects of anti-rheumatic drugs on in vitro mitogenic stimulation of peripheral blood mononuclear cells.

The efficacy of bromocriptine, chloroquine, and Cs was quantitated in an in vitro system, with the use of mitogen-stimulated human PBMC. A concentration-dependent effect was found for each drug. Based on counts of blast cells, Cs was roughly 70 times more effective than either bromocriptine or chloroquine. Besides quantitative comparison of the effect of the drugs, the in vitro system permits conclusions concerning drug combinations. The effect of the combination of bromocriptine and Cs was equal to the expected effects of the separate drugs. However, the combined effect of chloroquine and Cs exceeded the sum of the effects of the individual drugs, which indicates synergy, not addition.