Box and Whisker plot of serum GM-CSF Ab Concentration by Disease Behavior Categories. Serum GM-CSF Ab concentration was measured by ELISA and is shown as the median(IQR). Differences between groups were tested with the Kruskal-Wallis test. The serum GM-CSF Ab concentration increased from 0.8 (0.4, 2.3) mcg/mL in CD patients with inflammatory behavior (B1), to 5.1 (2.1,16.3) mcg/mL in those with LN, and 5.5 (1.6,7.2) in those with stricturing behavior (B2). *p=0.03, **p=0.002. Note: Disease behavior categories defined using Paris Criteria. B1: Inflammatory only, LN: Inflammatory with luminal narrowing, B2: Stricturing only, B3: penetrating only, B2B3: Both stricturing and penetrating behavior