Background Mechanisms regulating the chronic autoimmune response in rheumatoid arthritis (RA) are not well understood. However, activated T CD4+ play a pivotal role initiating and perpetuating the chronic inflammation characteristic for the disease.

Objectives Evaluate the number and distribution of circulating CD4+ T lymphocytes and their CD4+ naïve T cells (T_N), central memory (T_CM), non-terminated effector memory (T_NTEM) and terminated effector memory (T_TEM) T cells subsets in a population of recently diagnosed DMARD naive RA patients before and along the first 6 months of methotrexate (MTX) treatment.

Methods The number of circulating CD4+ T lymphocytes, and of their T_N, TM, TCM and TEM subsets in fifty untreated patients with RA before MTX treatment and at 3 and 6 months of treatment were assayed using a multiparametric flow cytometry. We also studied twenty-four age- and sex-matched healthy subjects as controls.

Results RA naïve patients show a significant (p<0.05) expansion of the circulating CD4+ T_NTEM subset. MTX non responder naïve RA patients show from basal conditions a significative expansion of CD4+ T_NTEM lymphocytes and develop significant expansion of CD4+ T_CM, and CD4+ T_EM lymphocyte subsets along MTX treatment.

Conclusions Recently diagnosed DMARD naive RA patients show involvement of the circulating CD4+ T lymphocytes activation/differentiation stage subsets. MTX treatment show immunomodulatory effects on CD4+ T lymphocyte compartment with different behavior in responder and non-responder patients.

Disclosure of Interest None declared