Release of lactoferrin by polymorphonuclear leukocytes after aerosol challenge with Escherichia coli.

Mice with cyclophosphamide-induced granulocytopenia were challenged with aerosolized Escherichia coli, their lungs were lavaged at 1 and 4 h, and total cell counts, differential counts, and levels of lactoferrin, transferrin, and albumin were measured in the lung lavage fluid. Lung lavage fluid from cyclophosphamide-treated mice had few neutrophils and no increase in lactoferrin levels, whereas control mice had significant increases in both. Transferrin levels did not change in either group. Neutrophils are the source of increased lactoferrin levels in lung lavage fluid after aerosol challenge.