Endogenous SAA is the SJIA plasma factor required for the reversal of T_reg anergy. (A top) Percentages of proliferating T_eff and T_reg in suppression assays with HC plasma (n = 10) and SJIA plasma (n = 10) or in stimulation assays. (Bottom) Representative FACS plots of CFSE staining to track proliferation of T_reg and T_eff in suppression assays. (B) SAA levels in SJIA plasma at different disease stages (flare-F n = 16, quiescence-Q n = 17, remission-R n = 7) and HC plasma (n = 14). (C top) Effects of SAA-depleted SJIA plasma on T_eff and T_reg proliferation in suppression assays (n = 2). Negative control for SAA depletion was performed with anti–HLA-DR antibody. (Bottom) Representative FACS plots of CFSE staining to track proliferation of T_reg and T_eff in suppression assays. Unpaired 2-tailed t tests (A) and ANOVA (B) were used for statistical analyses. Horizontal bars represented median values; bar graphs represented means and SEs where indicated throughout the figure.