CD28 and rheumatoid arthritis: The aim of the present work was therefore to examine the number and distribution of circulating TN, TCM, TEM and TE CD4+ T lymphocyte subsets, their CD28 expression and their Vβ TCR repertoire distribution, before and after 3 and 6 months of MTX treatment in a homogenous group of recently diagnosed, DMARD-naïve patients with new-onset RA.