IL6 and chronic obstructive pulmonary disease: The COPD-TS showed high levels of IL-6 (18.9 pg/mL), IL-4 (102.9 pg/mL), and IL-5 (55.1 pg/mL) in comparison with SWOC (13.7 pg/mL, 74.5 pg/mL, and 35.7 pg/mL, respectively, p < 0.001) (Figures 2A, C, D; Supplementary Table S5).