Pulmonary cell infiltration after chronic exposure to (1-->3)-beta-D-glucan and cigarette smoke.

To evaluate the effect of a microbial cell wall component--(1-->3)-beta-D-glucan--on the inflammatory effect induced by cigarette smoke in a subchronic exposure situation. Groups of guinea-pigs were exposed 5 days/week to cigarette smoke, an aerosol of (1-->3)-beta-D-glucan, or to both. The numbers of different inflammatory cells were studied in histological sections, enzyme digested lung tissue and in lung lavage. Cell enzyme production was measured. Exposure to (1-->3)-beta-D-glucan or cigarette smoke caused only minor alterations in inflammatory cells. Given together they caused an increase in cellularity in the tissue with significantly increased numbers of macrophages, lymphocytes, neutrophils and eosinophils. There was also an increase in subepithelial eosinophils. Lung lavage cell enzyme production was slightly lower in the combined exposure group. The results demonstrate that (1-->3)-beta-D-glucan synergistically increases the inflammation induced by cigarette smoke. The mechanism may be a downregulation of the macrophage control of inflammatory cell migration into the lung tissue.