Relation of sputum and BAL neutrophils to the development of Chronic Lung Allograft Dysfunction after lung transplantation

Abstract

Introduction: Chronic lung allograft dysfunction (CLAD) is a serious complication after lung transplantation (LTx), associated with elevated proportions of neutrophils (%PMN) in bronchoalveolar lavage (BAL). Induced sputum (IS) is less invasive than BAL to assess markers of inflammation (%PMN) in central airways. Aims: To examine whether IS %PMN levels were elevated early after LTx and further compare the utility of IS (vs BAL) %PMN to predict CLAD development. Methods: IS and BAL samples were collected at 4-8 and 12 weeks post LTx and IS collected annually in 30 patients, of which 10 later developed CLAD. The %PMN were determined by differential cell count and flow cytometry. CLAD was diagnosed in accordance with international guidelines. Results: CLAD occurred after a mean (SD) of 245 (156) days. At this time, %PMN in IS was higher among patients with CLAD, being 69 (17)% vs 49 (21)%, p=0.01. There were no statistical differences in %PMN in BAL or IS at earlier time points between those who later developed CLAD and those who did not. Using logistic regression, we found no relationship between %PMN at either 4-8 or 12 weeks after transplant, and presence of CLAD at 1, 2 or 3 years post LTx. Conclusion: The %PMN significantly discriminated CLAD from non-CLAD patients at time of diagnosis. The %PMN in samples of BAL and IS taken early after LTx did not predict development of CLAD up to 3 years post LTx. IS appears to give comparable information to BAL early after LTx and may be considered as a less invasive alternative to BAL for PMN surveillance post LTx.