A3.13 Investigating T-Cell Subsets in Lymph Node Biopsies of Autoantibody Positive Individuals and Early Arthritis Patients

Background Rheumatoid arthritis (RA) is an immune-mediated inflammatory disease of unknown aetiology. Recent work has shown that systemic autoimmunity precedes inflammation of the synovium in RA patients. We developed a method to study the cellular composition of lymph nodes in the earliest phases of RA. Objective Cross-sectional analysis of the phenotype and functional characteristics of T cells from lymph nodes of individuals in different phases of rheumatoid arthritis. Materials and Methods Seven individuals with arthralgia but without any evidence of arthritis upon physical examination who were/but positive for IgM rheumatoid factor (IgM-RF) and/or anti-citrullinated protein antibodies (ACPA; RA risk group) and 7 DMARD and biological naïve RA patients were included in the study. All study subjects underwent ultrasound-guided inguinal lymph node biopsy. T cell subsets T-helper (Th)1, cytotoxic T cell (Tc)1, Th2, Tc2, Th17, Tc17, regulatory T cells (Treg) and follicular T cells (Tfh) were analysed by multi-colour flow cytometry. Cytokine profiles were determined after stimulation with Phorbol Myristate Acetate (PMA) and Ionomycin in the presence of Brefeldin A and Golgi Stop. We used directly labelled antibodies for CD45, CD3, CD4, CD8, IFN-y (Th1/Tc1), IL-4 (Th2/Tc2), IL-17A (Th17/Tc17) foxp3, and IL-10 (Treg). Results Different T-helper cell subsets could be distinguished in the RA risk and arthritis group. An increase of CD4+IL-17A T cells (Th17; p = 0.04) and of CD4+IL-10 producing T cells (p = 0.014) could be observed in the early arthritis group compared to the RA risk group. Interestingly, a significant correlation between CD4+IL-10 producing T cells and ACPA titers (r = 0.78; p = 0.0016) and between CD4+IL-17A producing T cells and IgM-RF levels (r = 0.57; p = 0.04) was found when combining both study groups. In addition, within the RA risk group the levels of CD4+ IL-10 producing T cells correlated significantly with the TOTTJC28 (r = 0.8097; p = 0.03). Within the early arthritis group no significant correlations between T cell subsets and disease activity were found. Conclusions Flow cytometry analysis of cells collected using ultrasound-guided inguinal lymph node biopsy suggests an increase in activated T cells producing IL-17A and IL-10 in patients with early RA. Moreover, the number of these T cells correlates with autoantibody levels suggesting an important role of these T cells in the humoral autoimmune response. These data indicate that i