Thursfield RM, et al. - Researchers investigated the links between vitamin D, antimicrobial peptides cathelicidin (LL37) and human-beta-defensin-2 (HBD-2), and airway infection, inflammation and physiology in children with CF, presuming that antimicrobial peptide levels would be decreased, and airway infection and inflammation greater, in CF children with vitamin D deficiency. No association was observed between serum vitamin D and bronchoalveolar lavage HBD-2 or LL-37. In this first bronchoscopic study on this topic, it was shown that vitamin D deficiency was not related to immunological, infective or clinical markers of disease severity in patients with CF or chronic suppurative lung disease.