High-level tnf-α secretion and macrophage activity with soluble β-glucans from saccharomyces cerevisiae

We have previously reported that water-soluble β- glucan completely devoid of mannoprotein and purified from the yeast cell wall effectively stimulated the macrophage function (Biosci. Biotechnol., Biochem., 65, 4, 837-841 (2001)). In this present study, to increase the yield of water-soluble β-glucan, the wild type of Sacharomyces cerevisiae, JH, was treated with a combination of UV irradiation and laminarinase (endo-β-(1,3)-glucanase) to yield the laminarinase-resistant mutants, JUL1 and JUL3. Water-soluble β-glucans that were free of mannoprotein from JH, JUL1 and JUL3 were purified and their effects on TNF-α secretion and phagocytosis by macrophages were evaluated. Crude β-glucan was first solubilized from the yeast cell wall by alkaline extraction and then subjected to an acid treatment. The residual mannoprotein was completely removed by DEAE and ConA chromatography. The yield of water-soluble β-glucan in both mutants (JUL1, 5.11%; JUL3, 5.76%) was about 5-fold higher than that of the wild type (1.16%). The water-soluble β-glucan from JH induced TNF-α secretion slightly more than that from JUL1 or JUL3: TNF-α secretion by JH at 50, 200, 500 μg/ml of β-glucan was 11-17% more than that by JUL1 or JUL3 for the same treatment. β-Glucan from the wild type stimulated phagocytosis slightly more than that from the mutants. These mutants could therefore effectively produce purified water-soluble β-glucan with immune activity.