RESUMO
<p><b>OBJECTIVE</b>To study the effects of polysaccharides of cultured Cryptoporus volvatus(CVPS) on airway hyperresponsiveness of ovalbumin-sensitized rats and to evaluate their mechanisms.</p><p><b>METHODS</b>Polysaccharides A, B (5mg/kg, 20mg/kg) and ketotifen(5mg/kg) or vehicle(same volume of saline) were administrated orally for 10 days in ovalbumin -sensitized rats, methacholine bronchial provocation tests were performed to determine airway hyperresponsiveness. Bronchoalveolar lavage fluid (BALF) and peritoneal lavage fluid were prepared after the animals were challenged by nebulized antigen. The differential white cell count in BALF,and the degranulated mast cell count as well as differential white cell count in peritoneal lavage fluid were performed.</p><p><b>RESULT</b>Polysaccharides markedly inhibited the increased lung resistance and the decreased lung compliance induced by antigen challenge,significantly reduced total cell counts and absolute eosinophil counts in BALF(P<0.05); polysaccharides B was more effective than polysaccharides A. They also inhibited recruitment of inflammatory cells in peritoneal lavage fluid and inhibited the allergen-induced mast cell degranulation.</p><p><b>CONCLUSION</b>Polysaccharides of CVPS inhibit airway hyperresponsiveness by stabilizing mast cell membranes and reducing infiltration and chemotaxis of eosinophils and may be developed as a potential anti-asthmatic drug.</p>