Increased bronchoalveolar lavage fluid CD1c expressing dendritic cells in idiopathic pulmonary fibrosis

Background: Chronic inflammation is implicated in idiopathic pulmonary fibrosis (IPF) pathogenesis and is associated with persistent activation of immune responses. These are largely controlled by dendritic cells (DCs). Although large numbers of DCs infiltrate the lungs of patients with IPF, there are no similar reports in bronchoalveolar lavage fluid (BALF). Objectives: We aimed to investigate DC populations in BALF of IPF patients. Methods: CD1c+ myeloid DCs, BDCA3high myeloid DCs, BDCA2+ plasmacytoid DCs and CD83+ mature DCs were identified by flow cytometry in the BALF of 10 IPF patients and 10 controls. DC numbers were expressed as percentages of total BALF leukocytes. Results: CD1c+ myeloid DCs were increased in IPF patients versus controls [median (ranges in parentheses) 1.16% (0.25–3.97) vs. 0.61% (0.19–1.10), p = 0.01]. There was also a trend towards increased BDCA3high myeloid DCs [0.57% (0.23–0.88) vs. 0.28% (0.07–0.96), p = 0.07]. No differences were reported in BDCA2+ DCs and CD83+ DCs between IPF patients and controls. Conclusions: IPF is associated with an increase in percentages of BALF myeloid DCs. Considering that such an increase was not observed in CD83+ mature DCs, most of these DCs should be immature.