['To evaluate the effects and the possible mechanism of Cryptoporus polysaccharides (CP) extracted from fruiting body of Cryptoporus volvatus in lipopolysaccharide (LPS)-induced acute lung injury (ALI) in rats and mice.', 'Acute lung injury was induced by intratracheally instillation of LPS into lung in either rats or mice, assessing leukocyte numbers and myeloperoxidase activity in bronchoalveolar lavage fluid, as well as evaluating cytokines mRNA and protein expressions, and Toll-like receptor 2 (TLR(2)) and nuclear factor (NF)-κB mRNA levels in the lung tissues of mice. Vascular permeability and edema of lung in mice, and arterial blood gas in rats were also performed.', 'In ALI, CP-treated mice and rats exhibited significantly reduced leukocyte invasion, myeloperoxidase activity, vascular permeability, edema of lung, as well as tumor necrosis factor-α and Interleukin-1β mRNA and protein expressions in the lung tissues compared with vehicle-treated mice. TLR(2) and NF-κB mRNA levels of the lung tissues were decreased in CP-treated mice in response to LPS. And decline in arterial blood gas was recovered in CP-treated rats.'] Does cyptoporus polysaccharide prevent lipopolysaccharide-induced acute lung injury associated with down-regulating Toll-like receptor 2 expression?