P71 Reduced airway beta-defensin 2 levels in children with cystic fibrosis and vitamin D-deficiency

Vitamin D (vD) levels have been reported to correlate with (a) lung function in healthy populations and (b) disease severity in pulmonary TB, COPD and asthma. The proposed mechanism, supported by in vitro studies, relates to vD response elements in the promoter regions of genes encoding molecules involved in innate immunity such as defensins and cathelicidin (LL-37). As patients with CF are at risk of fat and fat-soluble vitamin malabsorption, we sought to explore this relationship in a cohort of CF children. Frozen serum and bronchoalveolar (BAL) fluid samples, which had been donated for research at the time of a clinically-indicated bronchoscopy were available from 49 children with CF. Mean age at the time of the procedure was 6.8 years (range 0.03–15.99). 44 (90%) were biochemically pancreatic insufficient and were prescribed pancreatic enzyme supplementation and fat-soluble mulitvitamins. Serum 25OH vD3 was measured using HPLC and mass spectrometry. BALF human beta defensin-2 (hbD2) and LL-37 were quantified using ELISA. vD deficiency was defined as