Abstract
Rationale: Dendritic cells (DCs) are highly plastic and their characterization in human tissues has been hampered by lack of standardized immunohistochemical identification strategies. This study validates an immunohistochemical method for masking confounding non-DC cells and characterizes multiple DC populations in COPD-affected lungs.
Methods: Lung specimens were obtained from 27 COPD patients and divided into three levels of severity; GOLD I (n=6), GOLD II-III (n=11) and GOLD IV (n=10). Never-smokers (n=8) and non-COPD smokers (n=6) served as controls. Paraffin sections were double stained for combinations of macrophage and DC markers.
Results: Using the non-soluble DAB as the first detection chromogen it was possible to mask confounding non-DC cells e.g. CD68+ macrophages at a bright microscopic level. Using this approach two populations of CD68-CD11c+ and CD68-CD123+ cells were identified, indicative of myeloid and plasmacytoid DCs, respectively. The myeloid DCs, which were foremost BDCA3-, were significantly increased in diseased areas of COPD lungs, in particular in patchy areas of fibrosis and granuloma formation. Both CD68-CD11c+ and CD68-CD123+ cells displayed a dendritic morphology and were observed in epithelial and subepithelial compartments of small airways and alveolar walls as well as in lymphoid aggregates amidst CD21+ follicular DCs. Further combination of markers could discriminate intraepithelial myeloid and plasmacytoid DCs from CD207+ and CD1a+ epithelial DCs.
Conclusions: This study demonstrates that masking of confounding non-DC populations improves the identification of lung DC populations and reveals novel aspects of their dynamics and heterogeneity in COPD lungs.
- © 2011 ERS
