Fig. 6From: Low human beta-defensin-2 levels in the sputum of COPD patients are associated with the risk of exacerbationsPaired analysis for the comparison of within-patient levels of CXCL10 (A, B), CXCL11 (C, D), and IFN-γ (E, F) at baseline and the first virus (+) exacerbation. Statistical methods: Significance was calculated using the paired Wilcoxon signed-rank test (for more details about Fig. 6, see Additional file 1: Table S7)Back to article page