Interestingly, PBMCs from non-smokers (Figure S1A in Supplementary Material) and smokers (Figure S1B in Supplementary Material) were less responsive in terms of IL-18 release compared with PBMCs obtained from unstable COPD patients (Figure S1C in Supplementary Material), which instead showed a significant increase. Here, IL18 is linked to chronic obstructive pulmonary disease.