Suppressive effect of Chinese medicinal herb, Acanthopanax gracilistylus, extract on human lymphocytes in vitro.

We studied the effect of a Chinese medicinal herb, Acanthopanax gracilistylus, extract (AGE), on human lymphocytes in vitro. AGE markedly suppressed the proliferative responses of human peripheral blood lymphocytes stimulated with mitogens concanavalin A (Con A) and Staphylococcus aureus Cowan I (SAC). Both T cell and B cell activities-production of interferon-gamma and immunoglobulin-were suppressed by AGE. The mechanism of AGE-induced suppression of lymphocytes is to arrest the cell cycle at the G0/G1 stage without a direct cytotoxic effect. AGE also suppressed the alloantigen-specific cytotoxic T lymphocyte response. However, natural killer cell activity was less sensitive to the suppressive activity of AGE. In contrast, AGE markedly enhanced monocyte function to produce cytokines. These activities of AGE were associated with a 60-kD protein which was sensitive to treatment with pronase E, but not with NaIO4. These results suggest that AGE has an immunomodulating activity on human lymphocytes and its properties could be clinically applied in the treatment of several diseases such as autoimmune and allergic diseases.