We aimed to clarify the association of MBL and immunoglobulin deficiencies and ficolin-2 concentration, respectively, with COPD exacerbation risk in participants of a previously published randomized, placebo-controlled and double-blind trial comparing 5 vs. 14 days of glucocorticoid treatment for acute COPD exacerbations. This evidence concerns the gene FCN2 and chronic obstructive pulmonary disease.