Objectives We investigated whether Abatacept might reduce proinflammatory cytokine production by macrophages upon contact with cytokine activated T cells and/or stimulation with TLR ligands.

Methods Macrophages and cytokine stimulated T cells (Tck) were added together in the presence of Abatacept or a control Ig, with or without TLR ligands. The production of cytokines was determined by luminex.

Results Abatacept reduced Tck-induced production of TNFa by macrophages. Tck and TLR ligands synergistically induced the production of proinflammatory cytokines by macrophages, especially IL-12p70. The production of IL-12p70 coincided with the production of IFNg, which were both reduced in the presence of Abatacept.

Conclusions Tck induce the production of TNFa by macrophages and facilitate the highly increased production of proinflammatory cytokines in the presence of TLR ligands. Abatacept was shown to potently suppress these pathways suggesting that its role may extend beyond antigen specific T cell mediated effector function.