Figure 4.

GITR ligation enhances ex vivo proliferation and effector molecule production of CD4⁺ and CD8⁺ TIL. Effects of soluble GITRL (1 μg/mL crosslinked with anti‐HA antibody) or 10 μg/mL humanized agonistic anti‐GITR antibody on proliferation of (a) CD4⁺ TIL, and (b) CD8⁺ TIL upon 4 to 5 days’ culture of tumor‐derived mononuclear cells with a suboptimal amount of anti‐CD3/CD28 beads. Proliferation was measured by determination of percentages of CD4⁺ or CD8⁺ T cells expressing Ki‐67 at the end of the culture. Baseline proliferation (= % of Ki‐67⁺ T cells in the absence of GITRL or antibodies) was normalized to 100% for each tested patient. Bars show mean percentages of Ki‐67⁺ CD4⁺ or CD8⁺ T cells in cultures relative to baseline proliferation in cultures derived from n = 9 patients with SEM. An irrelevant human IgG1 antibody served as an isotype‐matched control antibody for the anti‐GITR antibody. (c) Production of IFN‐γ and d) granzyme B in culture supernatant was quantified. Data of patients with detectable amounts of IFN‐γ or granzyme B are shown, each line represents one patient. * = p < 0.05; ** = p < 0.01.