© 2007 American Thoracic Society
Neutrophils Are a Source of HGF in the LungINSERM Unit 700, Université Paris 7 et Hôpital Bichat-Claude Bernard, Assistance Publique-Hôpitaux de Paris, Paris, France To the Editor: Dr. Chow suggests that the identification of neutrophils as a source of HGF in the lung might be an artifact of immunohistochemistry. We totally disagree with this conclusion. First, all our immunohistochemistry experiments used the adequate negative control (nonspecific immunoglobulin), allowing us to be confident with the specificity of immunolabeling (1–3). Second, our group has studied in depth the production of HGF by neutrophils (1). In brief, we demonstrated (1) that HGF was stored in secretory vesicles and in gelatinase/specific granules in blood neutrophils; (2) that this intracellular stock was rapidly mobilized by degranulation when neutrophils were stimulated; (3) that proHGF synthesis occurs during PMN maturation, since proHGF mRNA was found in bone marrow myeloid cells but was not detected in circulating neutrophils; and (4) that HGF was in the pro-HGF inactive form in mature blood neutrophils and was activated after secretion by neutrophils-derived serine protease(s) and then bound neutrophils-derived glycosaminoglycans (probably heparan sulfate) (1). Altogether, these experiments demonstrate without doubt that neutrophils are a source of HGF. Footnotes Conflict of Interest Statement: None of the authors has a financial relationship with a commercial entity that has an interest in the subject of this manuscript. References
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