Characterisation of CD8+ T cell subsets in the synovial fluid and peripheral blood of rheumatoid arthritis patients

Background and objectives Detailed information on CD8 + T cells in rheumatoid arthritis (RA) is still reduced. However, studies on animal models of arthritis from the authors9 team and others suggest a major potential role of CD8 + T cells in the pathogenesis of chronic polyarthritis. In the present study the authors characterised the phenotype and cytokine-production profile of CD8 + T cells from peripheral blood (PB) and synovial fluid (SF) of RA patients. Materials and methods Unstimulated CD8 + T cells from the PB and SF of 40 patients with established RA were analysed by flow-cytometry for cell surface markers expression and intracellular cytokine production, and compared to the ones present in the PB of 15 healthy donors. Results 40% of the total T cells infiltrating the SF were CD8 + . The SF was characterised by a significant (p + T cells infiltrating the SF presented an effector phenotype (CD62L − CD27 − short-term effector, or CD62L − CD27 + central effector), and the presence of the activation markers CD69 and CD25 were significantly (p − CD27 − CD8 + T cells and in the SF central memory CD62L + CD27 + CD8 + T cells when compared to RA PB. The intracellular expression of the pro-inflammatory cytokines IFN-γ, interleukin-6, interleukin-17 and tumour necrosis factor-α in central memory CD62L + CD8 + T cells were significantly (p Conclusions The present study presents strong evidence for a marked role of CD8 + T cells in RA pathogenesis. The authors propose that activated effector CD8 + T cells, home into the SF, where they might contribute to articular destruction and maintenance of a chronic pro-inflammatory environment through the production of cytokines and cytotoxic agents.