[The in vitro potentiation of LAK cell cytotoxicity in cancer and aids patients induced by F3--a fractionated extract of Astragalus membranaceus].

The in vitro induction of LAK cell activity was studied in cancer and AIDS patients. F3, an immuno-regulatory component of Astragalus membranaceus was shown capable of potentiating the LAK cell inducing activity of rIL-2. The killing activity against Hs294T melanoma cell line of LAK cells induced by 50 U/ml rIL-2 in the presence of F3 (55 micrograms/ml) reached 64% which was comparable to that (60%) induced by 500 u/ml of rIL-2 alone. With F3 plus rIL-2, the effector to target cell ratio could be reduced to one-half in order to obtain an equivalent level of cytotoxicity when rIL-2 was used alone. In some patients, whose peripheral blood lymphocytes were relatively inert to rIL-2, F3 could make them responsive to rIL-2. These results imply that F3 may be useful to potentiate LAK cell activity, reduce the amount of rIL-2 and thus minimize the later's toxic side effects when used in vivo.