Lactoferrin restrains allergen-induced pleurisy in mice

Objectives The aim of this study was to assess the utility of lactoferrin (LF), a natural immunomodulator, to restrain allergen-induced pleurisy in mice. Material and subjects BALB/c female mice, 8- to 10-week old, weighing 24 g on average, were used. Treatment Mice were immunized intraperitoneally with 50 lg of ovalbumin (OVA) and the pleurisy was elicited 14 days later by intrapleural injection of 12.5 lg of OVA. LF was given 24 and 3 h before elicitation of the allergic reaction. Methods The cytokine levels in the pleural exudates were measured by immunoassays. The blood and pleural exu-dates smears were stained with Giemsa and May-Grünwald reagents and reviewed histologically. Lung sections were stained with eosin and hematoxylin for histological evaluation. Results Lactoferrin significantly decreased manifestation of pleurisy induced by OVA in a sensitized mouse model. In particular, the percentages of eosinophils in blood and pleural exudates were strongly diminished. The histological analysis of lungs revealed that LF diminished the develop-ment of pathological lesions, such as pulmonary edema, diffuse alveolar hemorrhage and hemosiderosis, which were found in the lungs after injection of the eliciting dose of OVA. LF also decreased the level of IL-5 secreted into the pleural fluid. Conclusions This is a first demonstration that LF signif-icantly decreases antigen-specific pleurisy in a sensitized mouse model