NK and NKT-like cells in granulomatous and fibrotic lung diseases

Background The pathogenetic and regulatory roles of natural killer (NK) and natural killer T-like cells in interstitial lung diseases (ILDs), fibrotic and granulomatous of unknown etiology are unclear. Objectives Here we investigated NK and NKT-like cells in peripheral blood (PB) and Bronchoalveolar lavage (BAL) from patients with ILDs. Method 190 patients (94 male mean age 61 ± 14.3 years) and 8 controls undergoing bronchoscopy for ILD diagnostic work-up were enrolled consecutively; 115 patients sarcoidosis, 24 chronic fibrotic hypersensitivity pneumonitis and 43 patients other ILDs [32 idiopathic pulmonary fibrosis (IPF) and 11 non-specific interstitial pneumonia (NSIP)]. PB and BAL were processed by flow cytometry using monoclonal antibodies to differentiate NK and NKT-like cells. Results NK% in BAL was significantly different among ILDs (p = 0.02). Lower NK% was observed in BAL from sarcoidosis than other ILDs (p < 0.05). Similar findings were observed for NKT-like, whereas no differences were found for PB NK%. Difference of NK% was observed between BAL and PB in all groups (p < 0.001). Sarcoidosis patients reported the best area under the curve for NKT-like (AUC = 0.678, p = 0.0015) and NK cells (AUC = 0.61, p = 0.001). In the IPF-NSIP subgroup, NK% cell was inversely correlated with FVC% (r = - 0.34, p = 0.03) and DLCO% (r = - 0.47, p = 0.0044). Conclusions NK and NKT-like were expressed differently in BAL from patients with different ILD and were significantly depleted in sarcoidosis respect to other ILDs. This suggests that these cells may play a protective role in the pathogenesis of sarcoidosis.