IL17A and rheumatoid arthritis: In addition, CD4+ T cells expressing both Foxp3 and IL-17 have been shown to be increased in the peripheral blood of patients with various autoimmune diseases, including systemic sclerosis, RA, and Crohn’s disease [35, 47, 49, 50], although the analysis of TSDRs of the foxp3 gene locus was not conducted in some studies, resulting in difficulty in discriminating between CD4+Foxp3+ T cell subsets originating from tTreg cells, pTreg cells, and effector T cells.