SELP and chronic obstructive pulmonary disease: Markers of platelet activation were significantly increased in sera from patients with COPD (CD40 ligand [Fig 5, B] and P-selectin); analysis of sputum by means of flow cytometry showed the presence of neutrophil-platelet aggregates (Fig 5, A), but we found no evidence of a correlation between the degree of platelet activation and NET formation (correlation between NET concentrations and CD41a+ neutrophils, P = .053).