RT Journal Article SR Electronic T1 Persistence of asthma following allergen avoidance is associated with proTh2 myeloid dendritic cell activation JF Thorax JO Thorax FD BMJ Publishing Group Ltd and British Thoracic Society SP 967 OP 973 DO 10.1136/thoraxjnl-2014-206364 VO 70 IS 10 A1 Froidure, Antoine A1 Vandenplas, Olivier A1 D'Alpaos, Vinciane A1 Evrard, Geneviève A1 Pilette, Charles YR 2015 UL http://thorax.bmj.com/content/70/10/967.abstract AB Background The natural history of asthma includes in some patients periods of disease remission, but the underlying mechanisms are unknown.Objectives We explored whether type 1 myeloid dendritic cell (mDC) dysfunction could be involved in the persistence of asthma, studying the controlled setting of occupational asthma after allergen avoidance.Methods We recruited 32 patients with occupational asthma to flour or latex ascertained by specific inhalation challenge and who were no longer exposed to the causal allergen. Leukapheresis was performed in each patient to isolate and characterise blood type 1 mDCs, and their functionality was studied in coculture with allogeneic CD4+ T cells from controls.Results At follow-up, 11/32 patients (34%) were characterised by the absence of symptoms and non-specific bronchial hyper-responsiveness to histamine and were considered to be cured. When compared with cured patients, mDCs from patients with persistent disease increased the production of interleukin (IL) 5 and IL-13 by CD4+ T cells, and upregulated programmed death ligand 2 (PD-L2) upon allergen pulsing. In addition, IL-5 and IL-13 responses could be reversed by exogenous IL-12, as well as by PD-L2 blockade.Conclusions This study indicates that pro-Th2 features of mDCs correlate with disease activity in asthma after cessation of exposure to the causal allergen. The findings also highlight that the Th2 programming by dendritic cells is flexible and partly mediated by PD-L2.