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Abstract

Readily available polysaccharides, amylopectin, amylose, dextrin, and yeast mannan, were chemically pliosphorylated using polyphosphoric acid in the presence of a tertiary amine, and the resultant phosphates were examined for their interferon-inducing activity in rabbits employing an assay system consisting of a primary culture of rabbit kidney cells and vesicular stomatitis virus. All the phosphates were shown to be active as interferon inducer, and, especially , the activity of those containing more than 2% phosphorus were quite strong. Interferons evoked by the above phosphates resembled those induced by bacterial endotoxin, e.g., the viral inhibiting activity was susceptible to heat treatment, low pH and tryptic digestion. Since all the parent polysaccharides showed no interferon-inducing activity, it is reasonable to assume that the active center of these inducers might reside or be due to the anionic phosphate groups.We have previously reported that the phosphomannans of the genus Hansenula are able to evoke rabbit serum interferon in considerable amounts. The above finding seemed to suggest the postulation that most of the acidic polysaccharides possessing phosphate moieties might also be able to behave as strong interferon-inducing substances. Phosphorylated polysaccharides, synthesized chemically by the reaction of several ordinary polysaccharides and polyphosphoric acid according to the recent description of Whistler and Dubin [10] were utilized in the present study. MATERIALS AND METHODSPolysaccharide preparations employed.