Fig. 4

Reversal of abatacept mediated blockade of autoantibody-mediated cytokine production by indoleamine 2,3-dioxygenase (IDO). Upper left: RT-PCR for IDO expression in nonstimulated monocytes and monocytes stimulated with cytotoxic T-lymphocyte-associated antigen 4 immunoglobulin (CTLA-4-Ig). Western blots for IDO, nuclear factor-κB-inducing kinase (NIK), and action (loading control) in nonstimulated monocytes and monocytes stimulated with CTLA-4-Ig. Levels of interleukin (IL)-6, IL-1β, IL-8, tumor necrosis factor (TNF)-α, and chemokine ligand 2 (CCL2) were measured in the supernatants of monocytes stimulated with 100 μg/ml anticitrullinated protein antibody (ACPA) immune complexes or rheumatoid factor (RF). Cultures were exposed to either 10 μg/ml CTLA-4-Ig (abatacept) or anti-TNF antibody (TNF-Ab) adalimumab with or without 1 mM IDO inhibitor (IDOi) 1-methyl-d-tryptophan. ** p < 0.05, *** p < 0.01