The paper is a review of the effects of inhaled (1-3)-Beta-D-glucan on lung cells and IgG formation. An acute exposure decreased the endotoxin-induced increase in neutrophils. In chronic exposures, a synergistic effect was seen. Endotoxin-induced ovalbumin IgG antibody formation was abolished by (1-3)-Beta-D-glucan. It is suggested that inhaled (1-3)-Beta-D-glucan interferes with the normal inflammatory reactions in the lung through an effect on macrophages.