CD4 and Arthritis: We conclude that Ptpn2 haploinsufficiency enhanced disease severity and caused identical immunophenotypes — accumulation of IL-17+CD4+ T cells and colon-enriched RORγt-expressing Tregs in arthritic ankles and lymph nodes but not in the colonic lamina propria — in mannan-induced SKG arthritis (Supplemental Figure 4) and DSS-induced arthritis (Figure 3 and Supplemental Figures 5 and 6).