1-->3-Beta-glucan has been associated with pulmonary inflammation induced by exposure to fungal or yeast cell wall dust. 1-->3-Beta-glucan is the major cell wall component of yeast or fungi. However, the yeast cell wall contains several other components besides 1-->3-beta-glucans, such as mannan and chitin. Few studies evaluated the contribution of these other cell wall components to pulmonary inflammation. The present study compares a crude particulate yeast cell wall preparation (zymosan A) to purified yeast glucan, purified yeast glucan mannan, or purified yeast glucan chitin particles for their potency to induce mouse pulmonary inflammation after in vivo exposure. Mannan is the second most abundant polysaccharide in the yeast cell wall, whereas chitin content is a minor component. The results show that pulmonary injury is mediated by both chitin and 1-->3-beta-glucan and to a lesser degree by mannan. There is also evidence that zymosan is more potent than purified 1-->3-beta-glucan alone. Evidence indicates that 1-->3-beta-glucan is the major inflammatory component in yeast and fungal cell walls.