CHLOROQUINE AND HYDROXYCHLOROQUINE EQUALLY AFFECT TUMOR-NECROSIS-FACTOR-ALPHA, INTERLEUKIN-6, AND INTERFERON-GAMMA PRODUCTION BY PERIPHERAL-BLOOD MONONUCLEAR-CELLS

Objective. The efficacy of both chloroquine and hydroxychloroquine in rheumatoid arthritis (RA) has been proved in controlled clinical trial s. Despite similar chemical characteristics, it is believed the clinic al efficacy of chloroquine is superior to that of hydroxychloroquine i n patients with RA: Excessive production of proinflammatory cytokines was shown to contribute to the pathogenesis of RA. From different stud ies testing either chloroquine or hydroxychloroquine, it could be conc luded that both drugs differentially inhibit cytokine production. Meth ods, We compared the effects of both chloroquine and hydroxychloroquin e on stimulated peripheral blood mononuclear cells (PBMC) with respect to cytokine production. Therefore, PBMC were tested for tumor necrosi s factor-alpha (TNF-alpha), interleukin 6 (IL-6), and interferon-gamma (IFN-gamma) by specific ELISA, after stimulation with phytohemaggluti nin (PHA) or lipopolysaccharide (LPS) in the presence or absence of di fferent concentrations of chloroquine or hydroxychloroquine. Results, We observed that chloroquine and hydroxychloroquine equally inhibit PH A induced TNF-alpha and IFN-gamma production, and LPS induced TNF-alph a and IL-6 production, while PHA induced IL-6 production was not affec ted. Conclusion. Chloroquine and hydroxychloroquine display similar ef fects on PHA and LPS induced cytokine production by PBMC under identic al in vitro conditions. These findings may help in understanding the m echanism of action of these drugs on RA.