Figure 1.

T-cell/dendritic cell interactions in health and in systemic lupus erythematosus. Regulatory T cells (Tregs) (red) and effector T cells, shown as potentially pathogenic anti-self T cells (blue), can affect the maturation of immature dendritic cells (DCs) to immunogenic or tolerogenic antigen-presenting cells. Transforming growth factor beta (TGFβ) and IL-10 produced by Tregs promote tolerogenic DCs, and IFNγ or IL-17 produced by effector T cells promotes immunogenic DCs. Toll-like receptor (TLR) 7 and TLR9 stimulation by apoptotic bodies in systemic lupus erythematosus (SLE) results in type 1 interferon production, which promotes immunogenic DCs that activate potentially pathogenic self-reactive T cells. The feedback loop shown sustains immunogenic DCs and, secondarily, results in decreased Tregs.