The effects of endotoxin and glucans on alveolar macrophage function were studied in-vitro and in-vivo. Enterobacter-agglomerans extract, E-agglomerans endotoxin, glucan-1 (9012720) and glucan-2 (9041229) were used in these studies. For in-vitro studies, alveolar cells were harvested from English-short-haired-guinea-pigs. Except for glucan-1, the microbial agents showed little cytotoxicity in alveolar macrophages (AMs) at 100 micrograms/milliliter (microg/ml); all agents except for glucan-2 exhibited cytotoxicity at 1,000microg/ml. When AMs were treated in- vitro with 10microg/ml of endotoxin or glucan, the bactericidal index increased 33 to 55%. AM exposed to the microbial agents at 10microg/ml showed enhanced production of superoxide anion ranging from 68 to 425% above control values. All microbial agents stimulated AM to release chemotactic factors, and glucan-1 was most potent. Thymocyte proliferation factor was stimulated by in-vitro exposure to endotoxins, but glucan-1 and glucan-2 were ineffective. For in-vivo studies, guinea-pigs were exposed in an inhalation chamber to 10 micrograms/milliliter (microg/ml) E-agglomerans endotoxin, E-agglomerans extract or 200microg/ml glucan-1 or glucan- 2 for 18 hours. Exposure of guinea-pigs to E-agglomerans extract resulted in an immediate increase in breathing rate that peaked at 12 hours; E-agglomerans endotoxin produced a smaller increase in breathing rate. Exposure to glucan-1 produced a small breathing rate response that was elevated at 3 and 12 hours. Endotoxin, the extract and glucans increased total cells, neutrophils, lymphocytes, and red blood cells in lavage fluids. The microbial agents increased superoxide anion in guinea-pigs. The author concludes that endotoxins and glucans produce consistent responses in AM both in-vivo and in-vitro that require further study.