CD8A and rheumatoid arthritis: In healthy individuals, T cells are exposed to self-antigens to maintain homeostatic proliferation.2 In autoimmune diseases, chronic stimulation of self-reactive CD8+ T cells can potentially drive effector CD8+ T cells to differentiate into an exhausted phenotype3 characterized by low proliferative capacity and low capacity of cytokine production.4, 5 Overall, these exhausted T cells display a functional hyporesponsiveness,4 which has been observed in several autoimmune diseases including rheumatoid arthritis (RA).6, 7