ANTIINFLAMMATORY AND IMMUNOREGULATORY ACTION OF METHOTREXATE IN THE TREATMENT OF RHEUMATOID-ARTHRITIS - EVIDENCE OF INCREASED INTERLEUKIN-4AND INTERLEUKIN-10 GENE-EXPRESSION DEMONSTRATED IN-VITRO BY COMPETITIVE REVERSE-TRANSCRIPTASE POLYMERASE CHAIN-REACTION

Objective. To look for in vitro modulation of the main immunoregulator y and antiinflammatory cytokines by methotrexate (MTX) during the cour se of rheumatoid arthritis (RA). Methods. We quantified interleukin-2 (IL-2), IL-4, IL-10, and interferon-gamma (IFN gamma) gene expression by peripheral blood mononuclear cells ex vivo under basal conditions a nd in vitro after stimulation with phytohemagglutinin (PHA) or PHA plu s MTX, by competitive reverse transcriptase-polymerase chain reaction (RT-PCR), in 12 patients with untreated active RA (group 1), 10 patien ts with MTX-treated disease in partial remission (group 2), and 11 hea lthy control subjects. Simultaneously, under the same experimental con ditions, we quantified cytokine production by specific enzyme-linked i mmunosorbent assays (ELISAs). Results. Under basal conditions, we foun d no differences in IL-2, IL-10, and IFN gamma gene expression in the 3 groups, while IL-4 gene expression was significantly decreased in RA patient group 1 compared with the control group. In vitro, under the action of MTX, IL-10 gene expression was significantly increased in th e 3 groups, IL-4 gene expression was significantly increased in RA gro up 1 and in the control group, and IL-2 and IFN gamma gene expression was significantly decreased in RA group 1, Cytokine gene expression as sessed by RT-PCR and cytokine production assessed by specific ELISAs w ere highly correlated. Conclusion. In vitro modulation of the cytokine network by MTX, increasing Th2 cytokines and decreasing Th1 cytokines , could explain its antiinflammatory and immunoregulatory actions in v ivo during the treatment of RA.