Behavior of lymphocyte subsets and expression of activation markers in response to immunotherapy with galactoside-specific lectin from mistletoe in breast cancer patients.

Cellular aspects of the immunomodulating activity of the galactoside-specific lectin from mistletoe (ML-1) were investigated in 10 cancer patients. Regular subcutaneous injections (4 weeks) of the optimal dosis of ML-1 (1 ng per kg body weight, twice a week) yielded notable increases in the apparent numbers of certain lymphocyte subsets [pan T cells; helper T cells; natural killer (NK) cells] which are generally believed to be involved in antitumor immunity. Moreover, ML-1 administration resulted in an increased level of expression of interleukin (IL)2 receptors on lymphatic cells, an indicator of cellular activation. In vitro, the exposure of human lymphocytes to ML-1 resulted in an enhanced expression of receptors for IL-2 (T cells) and HLA-DQ (B cells), which similarly substantiated the capacity of ML-1 to affect immunological parameters within the host defense system. Thorough clinical trials are now required to assess any impact of the application of the lectin on the course of the disease.