Reply to Puxeddu et al.: CD71− Alveolar Macrophages in Idiopathic Pulmonary Fibrosis: A Look beyond the Borders of the Disease

Abstract

other hypotheses, CD71 AMs could be an expression of a subpopulation of immature monocytes recruited into the alveolar space from the bloodstream during active inflammation/tissue injury, as was previously shown in a preclinical animal model of lung fibrosis (6). We believe that the lack of specificity about the presence of CD71 AMs in IPF that we show in this brief report supports the latter interpretation. Furthermore, the reported association between the proportion of CD71 cells and the clinical course of patients with IPF may reflect the ongoing fibrotic process that characterizes the rapidly progressive form of the disease and may also characterize other, non-IPF ILDs that in some cases display an accelerated pathological/clinical evolution. Although further studies on large populations of patients with ILD will be needed to confirm these preliminary observations, we believe that the study by Allden and coworkers is very promising and reinforces the role of BAL as a potential source of fundamental information in the field of translational medicine in respiratory diseases. n