Fig 1: CTLA4 inhibits the acquisition of cytotoxic features by CD4+ T cells. A Increased GzmA and GzmB expression in CD57+ CD4+ T cells from PBMCs of cancer patients (n = 7) after treatment with ipilimumab/nivolumab (anti-CTLA4/PD-1). Each symbol represents one cancer patient before (empty symbols) and after (filled symbols) treatment. B, D Tonsillar CD4+ TEM were stimulated with anti-CD3 beads, CD80/86-expressing irradiated Raji cells and IL-2 or IL-21 for 4 days. B Suppression of induced GzmA and GzmB expression in tonsillar CD4+ TEM cells by soluble CTLA4-Ig (n = 4). CTLA4-Ig binds to CD80/86 with higher affinity than CD28 to suppress costimulation (as shown in the diagram). C Increased GzmB expression in CD4+ T cells from Ctla4+/− mice. Ctla4+/+ or Ctla4+/− CD4+ T cells were stimulated with plate-coated anti-CD3, B cells (4T: 1B), IL-2 and IL-21 for 5 days. D Suppression of induced TCF1low cell formation from tonsillar CD4+ TEM by soluble CTLA4-Ig (n = 3–4). Summary data (mean ± SD) were collected from 2 to 3 independent experiments, and statistical analyses were performed by two-tailed unpaired t-tests (B and C), two-tailed paired t-tests (A) and two-way ANOVA with Bonferroni’s multiple comparison tests (D). P values are shown. NS not significant