IN-VITRO EFFECTS OF MISTLETOE EXTRACTS AND MISTLETOE LECTINS - CYTOTOXICITY TOWARDS TUMOR-CELLS DUE TO THE INDUCTION OF PROGRAMMED CELL-DEATH (APOPTOSIS)

The in vitro effects of therapeutically administered mistletoe extract s (ABNOBAviscum(R)) and pure mistletoe lectins (mainly mistletoe lecti n I) on a variety of human and murine tumor cell lines have been inves tigated Mistletoe extracts and purified mistletoe lectins inhibited in vitro the growth of all tumor cell lines tested including B cell hybr idomas, P815, EL-4, Ke37, MOLT-4 and U937. The mechanism of growth arr est was shown to be due to the induction of programmed cell death (apo ptosis). Thus, fragmentation of genomic DNA into oligonucleosomal band s of approximately 200 base pairs in length was observed within 20 h w hen tumor cells were incubated with mistletoe extracts or lectins. The se data point to a rational basis for the direct cytotoxic effects of mistletoe extracts and lectins apart from the postulated immunostimula tory properties of these agents.