Franciosi et al. used a commercial microfluidics-based mass spectrometer to quantitatively identify proteins in ELF from COPD patients and healthy controls.55 The results revealed the different levels of lactotransferrin, high-mobility group protein B1, alpha 1-antichymotrypsin and cofilin-1 in ELF from COPD patients and the controls. Here, SERPINA3 is linked to chronic obstructive pulmonary disease.