Lymphocytic bronchitis/bronchiolitis is one of the major risk factors for development of chronic rejection/BOS after lung transplantation. There is currently no established treatment available for this condition. There is now mounting evidence that IL-17 producing lymphocytes (TH17) not only participate in chronic allograft rejection/BOS, but are also present within the airway wall during lymphocytic bronchiolitis and that IL-17 mRNA-levels in bronchoalveolar lavage fluid of these patients are upregulated. As such, TH17 may account for the increased BAL neutrophilia seen in these patients, as IL-17 may be responsible for driving IL-8 secretion (a neutrophil-attracting chemokine) from various cell types in the airways. Since azithromycin has previously been shown to reduce both IL-17 induced IL-8 production by human airway smooth muscle cells 'in vitro' and bronchoalveolar IL-8/neutrophil levels in LTx recipients with established BOS, we believe that azithromycin has great potential for treating lymphocytic bronchi(oli)tis by attenuating this TH17/IL-17/IL-8-mediated airway inflammation, possibly even halting the subsequent development of chronic rejection/BOS after lung transplantation. In this study, histologic, spirometric, bronchoalveolar an radiologic features will be investigated in patients treated with confirmed lymphocytic bronchitis/bronchiolitis treated with azithromycin.