IFNG and arthritic joint disease: In mice with experimental arthritis, interferon-gamma (IFN-γ) from B cells is found to inhibit Tregs (Ellis and Braley-Mullen, 2017) (Figure 4), and the absence of B-cell-derived IFN-γ facilitates the transformation of CD4+ T cells into Tregs (Olalekan et al., 2015).