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Objectives CD4+CD8+ double-positive (DP) T cells are expanded in the peripheral blood of a subset of patients with RA. This study examines the clinical significance of DP T cells in RA. Methods In 70 RA patients, DP T cells were measured by flow cytometry. Clinical data were obtained, and hand and feet radiographs were scored according to the Sharp/van der Heijde (SvdH) method. The association between DP T cell frequency and erosive joint destruction was analysed by correlation and multiple logistic regression analysis. Results Nineteen RA patients (27.1%) displayed increased DP T cell frequencies, which correlated with age (r = 0.288, P =0.016). Expansion of DP T cells was associated with the occurrence of erosions (94,7% vs 43,1%, P Conclusion Expansion of DP T cells is associated with joint damage and frequent escalation of therapy, possibly suggesting a contribution to more severe RA.

Objective In autoimmune arthritis, TCR signalling is attenuated by peripheral tolerance mechanisms. We have described previously a population of inhibitory receptor LIR-1 expressing autoreactive CD8+ T cells in rheumatoid arthritis. Here, we investigated the role of CD8+ T cells in murine autoimmune arthritis by analysing their expression of the mouse orthologue of LIR-1, PIR-B. Methods Frequencies of PIR-B+CD8+ T cells were determined in the SKG arthritis model. The phenotype of those cells was determined ex vivo by FACS and functionality was investigated by means of cytokine production and cytolytic potential upon activation in vitro. Results SKG mice, under non-SPF (specific pathogen-free) conditions with clinical symptoms of arthritis, were found to harbour significantly increased frequencies of PIR-B+CD8+ T cells. Those cells showed a pro-inflammatory phenotype with preferential production of IL-17 and IFN-γ. The frequency of those cells correlated inversely with the arthritis score, indicating that they might represent autoreactive, but functionally inhibited, CD8+ T cells. Conclusion PIR-B+CD8+ T cells from SKG mice show a cytotoxic and pro-inflammatory phenotype. Inhibition of CD8+ T cell autoreactivity by PIR-B/LIR-1 receptor signalling might be a counter-regulatory mechanism to curb autoreactivity and arthritis.

Objective To evaluate antibodies against cyclic citrullinated peptide (anti-CCP antibodies) for their predictive value for severe joint destruction in rheumatoid arthritis (RA) and to examine their relationship to shared epitope (SE)-positive DRB1 alleles. Methods Concentrations of anti-CCP antibodies were determined in sera from 126 patients with recent onset RA who had been followed prospectively for 6 yr. Progression of joint destruction was evaluated according to Larsen by scoring radiographs from the hand and feet taken at baseline and after 1, 2, 4 and 6 yr of observation. In addition to clinical parameters, the presence of SE-positive DRB1 alleles and of rheumatoid factor IgM and IgA was determined. Results Anti-CCP antibodies were found more frequently and in higher concentrations in both DRB1*01-positive and in DRB1*04-positive SE-positive patients compared with SE-negative patients. Severe joint destruction as defined by a Larsen score in the upper third of the study population was predicted by positivity for anti-CCP antibodies, by the presence of SE-positive DRB1*04 alleles and by the presence of erosive disease at initial presentation. Multiple logistic regression analysis revealed that SE-positive DRB1*04 alleles and anti-CCP antibodies exerted a significant influence on the progression of joint destruction. Conclusion The association of anti-CCP antibodies with DRB1*01 and with SE-positive DRB1*04 alleles implies a functional role for the SE sequence motif. The determination of SE-positive DRB1*04 alleles and of anti-CCP antibody positivity facilitates the prediction of disease course and prognosis at the time of initial presentation.