Induction of anti-mistletoe lectin antibodies in relation to different mistletoe-extracts

Coley's Lessons Remembered: Augmenting Mistletoe Therapy

The following four observations point in the same direction, namely that there is an unleveraged potential for stimulating the innate immune system against cancer: (1) experimental treatments with bacterial extracts more than 100 years ago by Coley and contemporaries, (2) a positive correlation between spontaneous regressions and febrile infection, (3) epidemiological data suggesting an inverse correlation between a history of infection and the likelihood of developing cancer, and (4) our recent finding that a cocktail of pattern recognition receptor ligands (PRRLs) can eradicate solid tumors in cancer mice if applied metronomically. Because the main immunostimulating component of mistletoe extract (ME), mistletoe lectin, has been shown to be a PRRL as well, we suggest to apply ME in combination with additional PRRLs. Additional PRRLs can be found in approved drugs already on the market. Therefore, augmentation of ME might be feasible, with the aim of reattaining the old successes using approved drugs rather than bacterial extracts.

Safety and effects of two mistletoe preparations on production of Interleukin-6 and other immune parameters - a placebo controlled clinical trial in healthy subjects

BACKGROUND

In Germany, Iscucin® Populi (IP), a preparation from mistletoe growing on the poplar tree, is used in cancer therapy while Viscum Mali e planta tota (VM), a preparation from mistletoe growing on the apple tree, is used in patients with osteoarthritis. Since mistletoe preparations are suspected to induce production of potentially tumor promoting cytokines like interleukin (IL)-6, further studies on the immunological effects are of interest.

METHODS

In this 3-armed randomized, double blind clinical trial healthy volunteers received increasing doses of either IP (strength F, 0.0125%, G, 0.25% and H, 5%, each for 4 weeks), or VM (1:1000 [D3], 1:100 [D2] and 2% each for 4 weeks) or placebo (isotonic solution) subcutaneously twice per week over a period of 12 weeks. Physical examination was performed weekly. Routine laboratory parameters and immunological parameters (C-reactive protein (CRP), differential blood count, lymphocyte subsets, immunoglobulins, IL-6 and tumor necrosis factor (TNF)-α) were analysed every 4 weeks.

RESULTS

71 subjects were included in the study (IP = 30, VM = 21, placebo = 20) of whom 69 concluded it according to protocol. Application of IP strengths G and H caused strong local reactions at the site of injection. In parallel, a distinct eosinophilia (p < 0.001 compared to placebo) occurred. Furthermore, application of all IP concentrations resulted in an increase of CD4 cell counts (p < 0.05) compared to placebo. Stimulation of IL-6 production, CRP or relevant deviations in other laboratory parameters were not observed. Because of local reactions, IP strengths G and H were considered less tolerable than placebo. VM 2% was slightly less tolerable than placebo, caused only mild local reactions and an only small increase in eosinophile counts.

CONCLUSION

Treatment with IP results in eosinophilia and an increase of CD4 cells but not in an increase of IL-6 or CRP. No safety concerns regarding the two mistletoe preparations have been raised by this study. EudraCT-Number 2007-002166-35.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT01378702.

Immunologic effector mechanisms of a standardized mistletoe extract on the function of human monocytes and lymphocytes in vitro, ex vivo, and in vivo

Even though mistletoe extracts have been in clinical use for centuries their exact mode of action is still unknown. Currently, the application scheme for registered preparations is a dose-escalating scheme to thus reduce side effects. In this study, healthy controls and patients were evaluated for their immunologic response to treatment with a standardized mistletoe extract (Iscador). It shows a strong effect as adjuvant that induces TNF-alpha and IL-12, which was partly mediated via CD14. Desensitization of the TNF-alpha response could be shown after repeated application in vitro and in vivo. Furthermore, Iscador induces a specific lymphocyte sensitization upon multiple injections and production of IgG1- and IgG3 -mistletoe antibodies. Remarkably, a systemic bystander effect (heterologous immunity against other recall antigens) was observed after long-term treatment. In conclusion, dose-escalation reduces the monocyte-related clinical side effects. A T-lymphocyte sensitization stimulates mainly a specific Th1 response. The most interesting clinical long-term effect is the bystander stimulation of various memory T cells that might mediate in vivo antitumor and antiinfectious T-cell response under mistletoe-extract immunization.

Synergism between rViscumin and cisplatin is not dependent on ERCC-1 expression

Interactions between recombinant mistletoe lectin (rViscumin) and anticancer drugs were investigated in vitro. rViscumin enhanced the cytotoxic effects of vincristine, mafosfamide, idarubicin and cisplatin in the human leukemia cell lines K562 and KG1a. In human marrow progenitor cells, rViscumin inhibited colony formation and did not exert any protective activity against cisplatin-induced inhibition of clonogenicity. Quantitative real-time reverse transcription polymerase chain reaction analysis revealed that cisplatin treatment of K562 cells resulted in a 1.9-fold increase in mRNA expression of the nucleotide excision repair gene ERCC-1. This upregulation was not prevented when cells were post-incubated with rViscumin. Our study provides evidence that rViscumin is capable of enhancing cytotoxicity of anticancer agents in vitro. This synergism appears to be independent of transcriptional activity of DNA repair relevant genes.

Effect of a herbal protein, CI-1, isolated from Cajanus indicus on immune response of control and stressed mice

The effect of a herbal protein, CI-1, purified from the leaves of Cajanus indicus was evaluated as a probable immunomodulator on immune response in control and stressed mice. In mice, sensitized with sheep red blood cells (SRBC), CI-1 enhanced IgG level by 28% over control (P < 0.05). Primary and secondary antibody response to SRBC and bovine serum albumin (BSA) were significantly increased in CI-1 treated group. Furthermore CI-1 facilitated the delayed type of hypersensitivity (DTH) response to SRBC in sensitized mice and also enhanced leucocyte and macrophage migration inhibition response in immunized mice. A fewer mice displayed symptoms of anaphylactic shock after CI-1 administration at a dose of 6.0 mg/kg body wt. in BSA sensitized mice. The immediate effect of CI-1 on anaphylactic shock was not seen when 150 microg of CI-1 was injected in combination with BSA in the shocking injection. These results suggest that CI-1 influences both humoral and cell-mediated immune response.

Flow cytometric analyses of the specific activation of peripheral blood mononuclear cells from healthy donors after in vitro stimulation with a fermented mistletoe extract and mistletoe lectins

Immunostimulatory properties of mistletoe extracts derived from Viscum album L. (VAL) are well described, demonstrating activation especially of T, T-helper cells and monocytes/macrophages. In order to characterise in detail the communication between different cell populations, we studied mistletoe-induced expression of co-stimulatory signals and their ligands by flow cytometry. Peripheral blood mononuclear cells (PBMC) from 15 healthy controls were incubated for 7 days with a fermented VAL extract. VAL significantly upregulated the expression of the co-stimulatory molecule B7.1 (CD80) on monocytes/macrophages, but not B7.2 (CD86). No significant changes in the expression of either molecules on B cells could be found, suggesting that only monocytes/macrophages act as antigen presenting cells (APCs) in this in vitro system. Purified mistletoe lectins, components of most VAL extracts were also analysed, but did not induce similar responses of monocytes/macrophages. The receptor for B7 molecules, CD28, but not CTLA-4 (CD152), was also found to be significantly enhanced on CD4+ cells after VAL simulation. There was no evidence for activation of a B cell response via the CD40/CD40L pathway. Our data support the concept that stimulation by VAL extracts induces a specific T-helper cell reaction with monocytes/macrophages acting as APCs and purified lectins do not exert the same effects.