VISCUM-ALBUM L PREPARATION ISOREL MODIFIES THE IMMUNE-RESPONSE IN NORMAL AND IN TUMOR-BEARING MICE

The Viscum album (mistletoe) preparation Isorel is able to destroy tum our cells and to modify immune reactivity against a particular antigen in normal and in tumour-bearing animals, CBA/HZgr mice and methylchol anthrene-induced fibrosarcoma were used in these studies. A single dos e of Isorel M (140 mg/kg or 1400 mg/kg body weight) significantly incr eased the number of plaque forming cells if applied at the time of inj ection of sheep red blood cells or 1 day earlier,The application of Is orel 1 day after sheep red blood cells did not modify the number of pl aque forming cells in comparison to the controls, The higher the dose of Isorel the stronger is the immune response to sheep red blood cells , Furthermore, one dose of Isorel (140 mg/kg body weight) restored the suppressed immune response of fibrosarcoma-bearing mice to a signific ant extent, Besides modification of the humoral immune response, the s urvival time of C57BI/GoZgr male skin grafts on syngeneic female recip ients was significantly shorter if Isorel was applied at a particular time after grafting, However, according to plaque forming cell numbers , a prolonged application of Isorel was significantly immunosuppressiv e in normal mice and particularly in tumour-bearing mice, It should be mentioned that the doses of Isorel used in this experiment were much higher than generally used in cancer patients. In view of the immunomo dulating effects of Isorel, the monitoring of the immune response of t he patients treated with mistletoe preparations is to be recommended.