Anti-GITR treatment decreases bacteremia and improves sepsis survival. (A) C57Bl/6 mice were given an intraperitoneal injection of 300 μg anti-GITR (n = 9) or control antibody (n = 9) 30 minutes before cecal ligation and puncture (CLP) surgery and mice were killed at 6, 16, or 24 hours afterward. Bacteremia was determined from blood obtained aseptically via cardiac puncture plated on sheep blood agar plates. Data are represented as mean ± standard error. (B) C57Bl/6 mice were given an intraperitoneal injection of 300 μg anti-GITR (n = 35) or control antibody (n = 38) 30 minutes before CLP surgery and survival was monitored for 8 days. Figure is the combination of 2 separate experiments with similar results. (C) C57Bl/6 mice were given injections of CD4 depleting (n = 15) or control antibody (n = 20) as described in “Proliferation assay.” Survival after CLP was monitored for 8 days. (D) C57Bl/6 mice depleted of CD4 cells (n = 20) or not (n = 20) were given anti-GITR antibody 30 minutes before CLP surgery. Another group of non-CD4–depleted mice receiving control antibody was used as a control group. (E) C57Bl/6 mice depleted of CD25⁺ cells (n = 20) or not (n = 20) were given anti-GITR antibody 30 minutes before CLP surgery. Another group of non-CD25–depleted mice receiving control antibody was used as a control group.*P < .05 by Student t test (A) or Fisher exact test (B-E). All error bars indicate SD.