Activation of CD4-positive T cells by polysaccharide fractions isolated from the Cupressaceae Thuja occidentalis L. (Arborvitae).

Various mitogens have been described which act on different subpopulations of mouse and/or human peripheral lymphocytes. In recent years it has been mainly Japanese and German research teams that have isolated polysaccharide fractions with immunomodulative properties [1-3, 17]. In addition to fungal polysaccharides such as lentinan, schizophyllan, and PSK polysaccharide, which are basically in the experimental step of clinical use [6, 10, 13], the focus of attention has mainly been on plants belonging to the asteracean family, such as Echinacea purpurea and E. angustifolia, where an increase in granulocyte phagocytosis is observable. Thuja occidentalis L., a Cupressaceae, has hardly been investigated up till now. Several authors have demonstrated that allopathic extracts of this plant could be strong antiviral agents directed against plant and animal viruses [12, 3]. Polysaccharide fractions with molecular weights ranging between 5 x 10 and 1 x 10 and higher have been isolated from aqueous alkaline extracts of the herbal parts of Thuja occidentalis by ethanol precipitation and ultrafiltration using a Satorius Ultra Sart filtration cell [5].