Decreased peripheral blood T cell cytokine gene expression in rheumatoid arthritis

Currently, few informations are available about spontaneous production of T cell cytokines in rheumatoid arthritis (RA) peripheral blood (PB), because these cytokines are generally under the detection threshold of ELISAs. Because the Th1/Th2 balance could help to determine the outcome of RA, we used a sensitive and quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) method to mesure spontaneous T cell production of IL-2, IL-4, IL-10, and IFN-gamma mRNAs using unstimulated PBMC from 25 active RA patients, not taking any DMARDs for at least 6 weeks, and 19 healthy controls. Spontaneous IL-2 and IL-4 mRNA expressions are significantly lower in RA patients compared to healthy controls. Levels of IL-10 and IFN-gamma are similar in the two groups. No correlation was found between cytokine mRNA levels and clinical parameters. Spontaneous IL-4 and IL-10 mRNA levels are respectively correlated to the number of CD4+ T cells and to the number of monocytes in PB. After in vitro stimulation, IFN-gamma mRNA production by RA PBMC is significantly decreased. Most of the patients cannot be classified as having a T cell cytokine type 1 or type 2 secretion pattern in PB. IL-2 and IL-4 mRNAs in PB of active RA are produced at a low spontaneous level and the response to in vitro activation by mitogen is weak.