CD4 and rheumatoid arthritis: In this paper, we describe the novel CD4+FoxP3+CD28− T-cell subset (CD28− Treg-like cells) in RA patients revealing features of both Tregs and senescent T-cells: Treg surface/intracellular markers such as CD25, CTLA-4, and PD-1 as well as FOXP3 were all expressed by CD28− Treg-like cells, and they yielded signs of premature senescence including reduced TREC levels and an accumulation of γH2AX.