Granulocyte-colony stimulating factor levels in bronchoalveolar lavage fluid from patients with idiopathic pulmonary fibrosis

Background-Granulocyte-colony stimulating factor (G-CSF) is known as a pote nt neutrophil chemotactic glycoprotein in vitro but its contribution to che motactic activity in neutrophil mediated lung diseases is not yet known. Th e aims of this study were to determine whether G-CSF is present in high con centrations in bronchoalveolar lavage (BAL) fluid of patients with idiopath ic pulmonary fibrosis (IPF, also called cryptogenic fibrosing alveolitis), a neutrophil mediated lung disease, and to what extent G-CSF in BAL fluid c ontributes to neutrophil accumulation in the lung of patients with IPF. Methods-G-CSF concentrations in BAL fluid samples from 16 healthy volunteer s, 24 patients with IPF, and 73 patients with non-IPF lung disease were mea sured by enzyme linked immunosorbent assay. The relationship between G-CSF concentrations and neutrophil count in BAL fluid was also examined. Neutrop hil chemotactic activity (NCA) was measured in BAL fluid in healthy volunte ers and patients with IPF. The contribution of G-CSF to overall NCA in lung s with IPF was assessed by repeating the measurement of NCA after a complet e neutralisation of G-CSF bioactivity by anti-human G-CSF antiserum. Results-Detectable levels of G-CSF were found in BAL fluid of 83% of patien ts with IPF while the levels in all healthy volunteers were below the detec tion Limit. In patients with IPF a significant correlation was observed bet ween the BAL fluid neutrophil count and the concentration of G-CSF in the B AL fluid. The neutrophil count also correlated significantly with percentag e forced vital capacity. In BAL fluid samples from patients with IPF the me an NCA value was reduced by 35% after neutralisation with an anti-human G-C SF antiserum. Conclusions-G-CSF may be involved in enhancing neutrophil accumulation in t he lungs of patients with IPF.