MISTLETOE LECTIN-I, LECTIN-II AND LECTIN-III INDUCE THE PRODUCTION OFCYTOKINES BY CULTURED HUMAN MONOCYTES

The three mistletoe (Viscum album L.) lectins, ML I, ML II and ML III, were tested on their ability to enhance the secretion of the cytokine s tumor necrosis factor (TNF)alpha, interleukin (IL)-1 alpha, IL-1 bet a and IL-6 by human monocytes obtained from healthy donors. At lectin concentrations from 0.02 to 20 pg/ml (100-10000-fold lower than those showing toxic effects), stimulations of cytokine production several-fo ld over control values were observed. The immunoactivating concentrati ons by the three lectins were found different for each donor. At toxic concentrations, the amounts of IL-1 alpha, IL-1 beta and to a less ex tent of TNF alpha in monocytes supernatants were particularly high. Th e data are discussed in relationship with the cytotoxic and immunoacti vating effects of mistletoe lectins and their interest in cancer treat ment.