Decreased humoral immune response in the bronchi of rapid decliners with chronic obstructive pulmonary disease

Identification of COPD patients with a rapid decline in FEV1 is of particular interest for prognostic and therapeutic reasons.

To determine the expression of markers of inflammation in COPD patients with rapid functional decline in comparison to slow or no decliners.

In COPD patients monitored for at least 3 years (mean ± SD: 5.8 ± 3 years) for lung functional decline, the expression and localization of inflammatory markers was measured in bronchial biopsies of patients with no lung functional decline (FEV1% + 30 ± 43 ml/year, n = 21), slow (FEV1% ml/year, - 40 ± 19, n = 14) and rapid decline (FEV1% ml/year, - 112 ± 53, n = 15) using immunohistochemistry. ELISA test was used for polymeric immunoglobulin receptor (pIgR) quantitation "in vitro".

The expression of secretory IgA was significantly reduced in bronchial epithelium (p = 0.011) and plasma cell numbers was significantly reduced in the bronchial lamina propria (p = 0.017) of rapid decliners compared to no decliners. Bronchial inflammatory cell infiltration, CD4, CD8, CD68, CD20, NK, neutrophils, eosinophils, mast cells, pIgR, was not changed in epithelium and lamina propria of rapid decliners compared to other groups. Plasma cells/mm² correlated positively with scored total IgA in lamina propria of all patients. "In vitro" stimulation of 16HBE cells with LPS (10 μg/ml) and IL-8 (10 ng/ml) induced a significant increase while H₂O₂ (100 μM) significantly decreased pIgR epithelial expression.

These data show an impaired humoral immune response in rapid decliners with COPD, marked by reduced epithelial secretory IgA and plasma cell numbers in the bronchial lamina propria. These findings may help in the prognostic stratification and treatment of COPD.