SAT0042 TWO POPULATIONS OF PD-1HICD4 T CELLS WITH DISTINCT B CELL HELPING CAPACITY, ARE ELEVATED IN THE PERIPHERAL BLOOD OF PATIENTS WITH EARLY RHEUMATOID ARTHRITIS

Background A novel population of B helper cells, phenotypically CD4+CXCR5-PD-1hi, has been described in the synovial tissues and peripheral blood of seropositive RA patients with an established disease, and termed ‘peripheral helper’ (Tph) cells. Contrary to CD4+CXCR5+PD-1hi follicular helper T (Tfh) cells, Tph cells are not located in lymphoid organs but accumulate in inflamed tissues. The frequency and kinetics of circulating Tph cells have not been examined in patients with early, untreated RA. Objectives To study the frequency of circulating Tph (cTph) cells, and also of circulating Tfh cell counterparts (cTfh), in patients with early RA (eRA). Methods Peripheral blood was drawn from DMARD-naive early RA patients (2010 ACR criteria) with a disease duration Results Seropositive (RF+ and/or ACPA+, n=31) but not seronegative eRA patients (n=17), demonstrated increased frequencies and absolute numbers of cTph and cTfh cells. cTph but not cTfh cells expressed CCR2. Those eRA patients who experienced a significant clinical improvement at 12 months, demonstrated a marked reduction of their cTph whereas their cTfh cell numbers remained unchanged; at the same time, rheumatoid factor titres decreased significantly but ACPA (anti-citrullinated peptide antibodies) titres did not vary. Both CXCR5+ and CXCR5-CD4+ T cells were able to induce maturation of memory B cells, whereas only CXCR5+CD4+ T cells could differentiate naive B cells. Conclusion Two populations of PD-1hiCD4 T cells with distinct phenotype and B cell helping capacity, are increased in the peripheral blood of seropositive eRA patients. Whereas cTph are related with disease activity, cTfh cells seem to be constitutively elevated. Reference [1] Rao DA, et al. Nature2017 Disclosure of Interests Paula Fortea-Gordo: None declared, Laura Nuno: None declared, Alejandro Villalva: None declared, Diana Peiteado: None declared, Irene Monjo: None declared, Amaya Puig-Kroger: None declared, Paloma Sanchez-Mateos: None declared, Alejandro Balsa Grant/research support from: Abbvie, Pfizer, Novartis, BMS, Nordic, Sanofi, Consultant for: Abbvie, Pfizer, Novartis, BMS, Nordic, Sanofi, Sandoz, Lilly, Paid instructor for: Pfizer, Speakers bureau: Pfizer, Novartis, UCB, Nordic, Sanofi, Sandoz, Lilly, Maria-Eugenia Miranda-Carus Grant/research support from: Roche Pharma, BMS