The addition of anti-IL-15 antibodies (aIL-15ab) to antibiotics does not adversely affect the clinical course of S. aureus-induced arthritis. (A) Mice were i.v. inoculated with S. aureus LS-1 and treated 3 days later with (i) aIL-15ab with antibiotics for the combination therapy group or (ii) control antibodies with antibiotics for the control group. The antibodies were injected intraperitoneally at days 3, 6, and 10 postinfection. (B) The severity of arthritis was evaluated during the course of the infection. (C) Bacterial persistence in the kidneys at 12 days postinfection. (D) Weight change as a percentage of initial weight. (E) Cumulative survival during the 12-day period. Data are representative of three separate experiments with 10 mice/treatment group. (F) Femur trabecular bone mineral density (BMD) in the metaphysical region was measured by pQCT. Values from two experiments were pooled, with 10 mice/treatment group. In panels B and D, bars show the means ± standard errors of the mean. In panels C and F, data are shown as medians; the whiskers represent minimum to maximum ranges. Statistical differences were calculated using a Mann-Whitney U test. Kaplan-Meier survival plots were prepared, and a log-rank test was used for comparison between the two survival curves. Abbreviations: A, antibiotics; ctrl ab, control antibodies; aIL-15ab, anti-IL-15 antibodies.