BRONCHIAL HYPERRESPONSIVENESS IN LUNG-TRANSPLANT RECIPIENTS - LACK OFCORRELATION WITH AIRWAY INFLAMMATION

Background - Bronchial hyperresponsiveness (BHR) to methacholine has b een reported to occur in most lung transplant recipients. BHR to physi cal stimuli such as exercise and non-isotonic aerosols has not been as extensively studied in this subject population. This report aims to a ssess the presence and degree of BHR to methacholine and hypertonic sa line in stable lung transplant recipients and to relate it to the pres ence of airway inflammation. Methods - Ten patients undergoing bilater al sequential lung transplantation and six heart-lung transplant recip ients, all with stable lung function, were recruited 66-1167 days foll owing transplantation. Subjects underwent a methacholine challenge and bronchoscopy for sampling of bronchoalveolar lavage fluid, transbronc hial and endobronchial biopsy tissues. Hypertonic saline challenge was performed six days later. Results - Nine of the 16 transplant recipie nts had positive methacholine challenges (geometric mean PD20 0.18 mg, interquartile range 0.058-0.509) and three of these subjects also had positive hypertonic saline challenges (PD15 = 2.3, 33.0, and 51.5 ml) . No clear relationship was found between BHR to either methacholine o r hypertonic saline and levels of mast cells, eosinophils or lymphocyt es in samples of biopsy tissue or lavage fluid. Conclusions - Most of the lung transplant recipients studied were responsive to methacholine and unresponsive to hypertonic saline. BHR was not clearly related to airway inflammation, suggesting an alternative mechanism for BHR foll owing lung transplantation from that usually assumed in asthma.