A NOVEL TYPE OF B-CELL MITOGEN ISOLATED FROM JUZEN-TAIHO-TO (TJ-48), A JAPANESE TRADITIONAL MEDICINE

Juzen-taiho-to (TJ-48), a Japanese traditional medicine, is known to h ave various immunological activities including the induction of B-cell proliferation. We investigated the properties of the pectic polysacch aride fraction of TJ-48 (F-5-2) which is most active in the proliferat ion of spleen cells. To an extent equal to that of TJ-48, F-5-2 induce d the proliferation of B-cells, particularly those holding both sIgM a nd sIgD. The proliferation induced by F-5-2 was T-cell independent and macrophage dependent. The macrophages could be substituted for a solu ble factor(s) secreted from the macrophages but not for IL-1. Generall y, B-cell mitogens are known to induce the proliferation of B-cells an d subsequently differentiation into plasma cells. However,although F-5 -2 induced the B-cell differentiation, it arrested their development i n the intermediate stage of the B-cell differentiation. The B-cells in duced by F-5-2 produced IgM antibody in response to IL-6 and an antige n (SRBC) but not IgG antibody. F-5-2 induced the expression of IL-6R n ot only on IgM(+) and IgG(+) B-cells but also on IgD(+) B-cells. These results suggest that F-5-2 is a new type of B-cell mitogen.