Mitogenic activity of high molecular polysaccharide fractions isolated from the Cupressaceae Thuja occidentale L. I. Macrophage-dependent induction of CD-4-positive T-helper (Th+) lymphocytes.

The arborvitae or Thuja occidentale L., one of the Cupressaceae, has rarely been investigated until now. Several authors have demonstrated that allopathic extracts of this plant could be used as strong antiviral agents directed against plant and animal viruses. Polysaccharide fractions with molecular weights ranging between 20,000 and 1,000,000 and higher have been isolated from the aqueous alkaline extract of the herbal parts of T. occidentale L. by ethanol precipitation and fractionation by ultrafiltration. High molecular subfractions of Thujapolysaccharides (TPS) proved to be highly mitogenic on peripheral blood leukocytes. It was demonstrated by the alcalic immune phosphatase-antiphosphatase and Pappenheim staining methods that the mitogenic and cluster-forming activity of TPS cause T cell induction, in particular, of CD 4-positive T-helper/inducer cells as opposed to B cells. The CD-4+ T-helper/inducer cell induction is connected to an increased production of IL-2. The cluster-forming ability and mitogenity of TPS correlates well with the 3H-thymidine uptake and seems to be IL-1 and IFN-gamma dependent as could be shown by blocking the mitogenic effect using anti-IL-1- and anti-IFN antibodies. Whether it is possible to use these polysaccharide fractions as an adjuvant in the therapy of immune deficiency syndromes and cancer must now be further investigated.