Influence of treatment with the immunomodulatory effective dose of the beta-galactoside-specific lectin from mistletoe on tumor colonization in BALB/c-mice for two experimental model systems.

Mistletoe extracts have approval for clinical application. This warrants the quest for the definition of the active substances to optimize their application. Thus, the extent of immunomodulating and antimetastatic activity of the beta-galactoside-specific lectin from mistletoe extract (ML I) was investigated. In BALB/c-mice regular subcutaneous (s.c.) injections of small nontoxic doses of ML I yielded significant enhancement of peritoneal macrophage activity, as measured in chemiluminescence assays, as well as significant weight gain of thymus. Spleen weight, however, increased without statistical significance. To evaluate the anti-metastatic activity of ML I we intravenously (i.v.) inoculated sarcoma L-1 and fibrosarcoma RAW 117-H 10 cells which cause tumor colonization of lungs and livers in BALB/c-mice, respectively. After regular s.c. administration of ML I, the number of lung and liver tumor colonies significantly decreased in both experimental tumor models as compared to control mice which received injections of saline solution. Accordingly, ML I can be regarded as a potent immunomodulating and antimetastatic substance, which seems to be promising for clinical trials in human oncology.