Immunomodulating activity of 4-O-methyl-D-glucurono-D-xylan from Rudbeckiafulgida var. sullivantii

4-O-Methyl-D-glucurono-D-xylan from Rudbeckia fulgida var. sullivantii (Boy nton et Beadle) was tested for its immunomodulating activity. The substance at the concentration of 10 mu g/ml was cultivated for 48 h at 37 degrees C in an atmosphere of 5% CO2 with human monocytes (2 x 10(6) cells/ml) in RP MI 1640 medium with growth factors. After this activation a significant inc rease of the phagocytic activity and phagocytic index of human macrophages was observed. The candidacidal activity was not affected. The substance at a concentration of 0.5 mg/ml reduced the classical pathway of complement ac tivation but did not affect the alternative pathway. The higher and lower c oncentrations of the compound were not significantly effective. It has been concluded that 4-O-methyl-D-glucurono-D-xylan from Rudbeckia fulgida had a n immunomodulating activity on innate cellular and humoral immunity. The ac tivity is likely to be dose-dependent.