Box-and-whisker plots showing the severity of S. aureus-induced arthritis in leptin-treated NMRI mice (n = 20) and PBS-injected controls (n = 20), expressed as arthritic index (experiments 2 and 3). Boxes show the medians and the upper and lower quartiles. Whiskers show the 10th and 90th percentiles. The two highest and two lowest values are plotted as circles. The Mann–Whitney U test was used to evaluate statistical significance.