Effects after inhalation of (1→3)-β-D-glucan in healthy humans

Background and aim: This study was performed to assess the effects of an exposure to a pure (1 -->3)-beta -D-glucan, a cell wall component of fungi, plants and certain bacteria. Methods: Twenty-one healthy subjects inhaled saline or (1 -->3)-beta -D-glucan suspended in saline in a random, double-blind, cross-over design. They were examined before exposure and 24 and 72 h afterwards with spirometry, blood sampling and collection of induced sputum. Differential cell counts and eosinophilic cationic protein (ECP) were determined in blood and sputum, and myeloperoxidase (MPO), tumour necrosis factor-alpha (TNF-alpha), and interleukin (IL)-8 and IL-10 were determined in sputum supernatants. TNF-alpha was determined after cultivation of blood mononuclear cells. Results: In sputum, inhalation of saline caused a significant increase in ECP and TNF-alpha. (1 -->3)-beta -D-Glucan inhalation caused a further increase in these cytokines, although not statistically significantly different from the increase induced by inhalation of saline alone. in blood, the number of eosinophils was significantly decreased 72 h after the challenge with (1 -->3)-beta -D-glucan. This effect was not found after the inhalation of saline alone. TNF-alpha production from stimulated blood mononuclear cells was significantly decreased 72 h after the (1 -->3)-beta -D-glucan Inhalation as compared with the increase induced by saline inhalation. Conclusions: The results suggest that (1 -->3)-beta -D-glucan causes a different type of response as compared with inflammatory agents such as bacterial endotoxin that cause a neutrophil-dominated inflammatory response.