TY - JOUR T1 - Tocilizumab Treatment Decreases Circulating Myeloid Dendritic Cells and Monocytes, 2 Components of the Myeloid Lineage JF - The Journal of Rheumatology JO - J Rheumatol DO - 10.3899/jrheum.111439 SP - jrheum.111439 AU - Christophe Richez AU - Thomas Barnetche AU - Liliane Khoryati AU - Pierre Duffau AU - Marie Kostine AU - Cécile Contin-Bordes AU - Patrick Blanco AU - Thierry Schaeverbeke Y1 - 2012/04/01 UR - http://www.jrheum.org/content/early/2012/03/25/jrheum.111439.abstract N2 - Objective Interleukin 6 (IL-6) and tumor necrosis factor-α (TNF-α) are proinflammatory cytokines involved in inflammatory response. Effective TNF-α blocker treatment is associated with an increase in circulating myeloid dendritic cells (mDC), suggesting their release from inflamed synovium. Currently, in vivo effects of IL-6 inhibition on DC are unknown. We monitored the changes in circulating mDC and plasmacytoid DC (pDC) during tocilizumab (TCZ) therapy in patients with rheumatoid arthritis (RA). Methods DC subset levels were evaluated by flow cytometry in patients with RA (n = 43) and in healthy volunteers (n = 20). In patients with RA, these levels were measured before and during TCZ therapy (8 mg/kg every 4 weeks). Response to TCZ therapy was evaluated at 12 weeks. Statistical analysis was based on Mann-Whitney U tests or Wilcoxon signed-rank tests. Results At baseline, patients with active RA were characterized by a significantly lower level of circulating mDC and pDC compared to healthy donors. However, this difference did not correlate with any disease activity score. TCZ-treated patients who met the European League Against Rheumatism (EULAR) improvement criteria at Week 12 had significant reductions in mDC and monocyte levels as compared with EULAR nonresponders. Levels of pDC, CD4+ T cells, and CD8+ T cells remained stable during the TCZ courses, regardless of treatment response. Conclusion Our study reveals an unexpected reduction of circulating mDC and monocytes in patients with RA in response to TCZ therapy. In accord with reports on neutrophils and platelets decreasing during TCZ therapy, our data suggest an effect of IL-6 inhibition on cells from myeloid lineage. ER -