Correlation between immunological activity, molar mass, and molecular structure of different (1→3)-β-d-glucans

(1→3)-β-d-Glucans are said to be potential biomedical drugs against bacterial or viral infections and also show antitumour activity. These substances seem to enhance the activity of the immune system, but today there is no accepted mechanism, and not even any agreement on the parameters which influence the activity. Therefore, glucans with different structures and/or varying molar mass were characterized by multi-angle laser-light scattering coupled with size-exclusion chromatography in order to obtain the molar mass distribution and to gain an idea of the structure in solution. After ensuring that all samples were free of pyrogens, the Tumour-necrosis-factor-α release activity and the superoxide-anion released from human blood monocytes were measured in groups of samples with comparable polydispersity and degree of substitution. All glucans investigated, regardless of molar mass and solution structure, stimulate the investigated immunological measures more than a commercially available biomedical drug used for comparison. The greatest magnitude of molar mass was found to be about 550,000 g/mol for all the glucans investigated. Contrary to the cited literature, helical structures were not essential, and not even advantageous, for immunological activity. © 1997 Elsevier Science Ltd.