CD79A and chronic obstructive pulmonary disease: Finally, low serum IgA levels are associated with increased risk for COPD exacerbations (Putcha et al., 2018), while Ig replacement therapy in COPD patients with (IgG) antibody deficiency reduces the exacerbation rate and related hospitalizations (McCullagh et al., 2017), underlining the crucial role of infections and impaired local mucosal immunity in the pathogenesis of COPD exacerbations.