Background There are evidences supporting an expansion of CD4+ T lymphocytes in chronic and treated rheumatoid arthritis (RA) patients. The potential increased presence of these T cells in early RA remains elusive.

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 according to the CD28 expression 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 including their activation/differentiation stages (T_N, TM, TCM and TEM subsets) and the CD28 expression, in fifty untreated patients with RA before MTX treatment and at 3 and 6 months of treatment, were assayed using 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+CD28- T lymphocytes. The increased of this subset is mainly due to a significant elevator in the numbers of CD4+CD28- T naïve lymphocytes, CD4+CD28- T central memory lymphocytes and CD4+CD28- T non terminated effector memory lymphocytes.

Conclusions In this work, we have found that the expansion of CD4+CD28- T lymphocytes is already detected in recently and DMARD AR naïve patients. Moreover this increase of CD28- T lymphocytes is also found in CD4+ T naïve lymphocytes. This it is possible to suggest that the expansion of CD4+CD28- occurs associated to the development of the RA as a biological hallmark of the disease.

Disclosure of Interest None declared