Box-and-whisker plots of (a) serum concentration of leptin; (b) weight change in C57BL/6 mice (n = 9), before and after inoculation with S. aureus; and (c) serum concentration of leptin in leptin-treated NMRI mice (n = 10) during S. aureus-induced arthritis (experiment 2). Boxes show the medians and upper and lower quartiles. Whiskers show the 10th and 90th percentiles. The highest and lowest values are plotted as circles. The Wilcoxon signed rank sum test was used to evaluate statistical significance. n.s. = not significant.