Bronchial immunoglobulins and epithelial pIgR are upregulated in cystic fibrosis

Introduction: Immunoglobulin (Ig) A protects mucosal surfaces from inhaled pathogens and antigens. While serum and sputum IgA are increased, it remains unknown whether polymeric immunoglobulin receptor (pIgR)-mediated transepithelial transport of IgA is affected in cystic fibrosis (CF). Aims: We wondered whether broncho-epithelial pIgR-mediated transport of IgA is altered and could contribute to lung infection by Pseudomonas aeruginosa (PA). Methods: Lung tissue from 19 CF patients, as compared to 17 controls, was assayed for pIgR immunostaining. Sputum samples from 49 CF patients and 46 controls were assessed for IgA, secretory (S)-IgA, IgM, S-IgM, secretory component (SC) and PA-specific IgA and IgM, as well as neutrophil elastase (NE) activity. IgA and IgM. Total and PA-specific IgA and IgM were also measured in serum. Results: Increased epithelial pIgR immunostaining was observed in CF compared to controls, in large (56% versus 8, mean, p Conclusion: We report that, in contrast with COPD, broncho-epithelial pIgR expression is enhanced in CF and associates with an increased production of sputum IgA and IgM, including PA-specific antibodies, indicating that humoral immunity is upregulated in the CF lung.