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PubMed1992

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.

Biomarkers↗
PubMed1990

Histochemical response of mice to mistletoe lectin I (ML I).

The acute toxicity of lectin ML I from the toxic drug, mistletoe, was demonstrated in previous experiments. Because the reason for this extremely high toxicity is not yet clear, mice were studied histochemically at different times after treatment with various doses of ML I, ML I A or ML I B chain separately, or recombinations of ML I A and ML I B. Various plasma membrane-associated hydrolases as well as Golgi apparatus-and endoplasmic reticulum-linked hydrolases, peroxisomal and extraperoxisomal oxidases, lysosomal hydrolases, mitochondrial dehydrogenases, the cytoskeletal proteins keratin and vimentin as well as iron, glycogen and lipids were analysed in all organs and tissues of female mice. Irrespective of the dose, a clear-cut response was only observed in the liver. After ML I treatment, glycogen disappeared completely from all hepatocytes, and this effect did not depend on the ML I-concentration and exposure time. The increase in activity of Golgi-associated thiamine pyrophosphatase in hepatocytes and of non-specific alkaline phosphatase in the sinusoidal endothelial cells depended on the applied ML I concentration and the time of treatment. Doses of 600 or 900 ng ML I/kg drastically increased the phosphatase activities. These clear-cut changes of glycogen and enzyme activities were not observed after administration of the ML I B chain alone, and less so when the mice were treated only with the ML I A chain, or were treated with a recombination of ML I A and ML I B even at concentrations higher than that of ML I.(ABSTRACT TRUNCATED AT 250 WORDS)

Alkaline Phosphatase↗
PubMed1994

Staining of cerebral amyloid plaque glycoproteins in patients with Alzheimer's disease with the microglia-specific lectin from mistletoe.

Glycoconjugates in the amyloid plaques in the cerebral cortex of patients with Alzheimer's disease were stained with a lectin from mistletoe (ML-I). This lectin selectively stains microglial cells which can be found in the centre of many plaques. Since the terminal carbohydrate moieties of some but not all of the plaques, which mainly consist of beta A4 protein, are identical to those of the microglial cells it is concluded that glycoproteins within these plaques have been synthesised by the microglial cell. These microglia deposited glycoproteins may be of importance for the formation of mature amyloid plaques.

Alzheimer Disease↗
PubMed2003

Antitumor activity of the Korean mistletoe lectin is attributed to activation of macrophages and NK cells.

Inhibitory effect of the lectins (KML-C) isolated from Korean mistletoe (KM; Viscum album coloratum) on tumor metastases produced by murine tumor cells (B16-BL6 melanoma, colon 26-M3.1 carcinoma and L5178Y-ML25 lymphoma cells) was investigated in syngeneic mice. An intravenous (i.v.) administration of KML-C (20-50 ng/mouse) 2 days before tumor inoculation significantly inhibited lung metastases of both B16-BL6 and colon 26-M3.1 cells. The prophylactic effect of 50 ng/mouse of KML-C on lung metastasis was almost the same with that of 100 microg/mouse of KM. Treatment with KML-C 1 day after tumor inoculation induced a significant inhibition of not only the experimental lung metastasis induced by B16-BL6 and colon 26-M3.1 cells but also the liver and spleen metastasis of L5178Y-ML25 cells. Furthermore, multiple administration of KML-C given at 3 day-intervals after tumor inoculation led to a significant reduction of lung metastasis and suppression of the growth of B16-BL6 melanoma cells in a spontaneous metastasis model. In an assay for natural killer (NK) cell activity, i.v. administration of KML-C (50 ng/mouse) significantly augmented NK cytotoxicity against Yac-1 tumor cells 2 days after KML-C treatment. In addition, treatment with KML-C (50 ng/mouse) induced tumoricidal activity of peritoneal macrophages against B16-BL6 and 3LL cells. These results suggest that KML-C has an immunomodulating activity to enhance the host defense system against tumors, and that its prophylactic and therapeutic effect on tumor metastasis is associated with the activation of NK cells and macrophages.

Animals↗
PubMed2004

Isolation of epi-oleanolic acid from Korean mistletoe and its apoptosis-lnducing activity in tumor cells.

A triterpene was isolated as a cytotoxic principle from the dichloromethane extract of Korean mistletoe (KM; Viscum album coloratum) by repeated silica gel chromatography and recrystallization. In in vitro analysis of cytotoxic activity using various human and murine tumor cell lines, the dichloromethane extract of KM was highly cytotoxic against these cells. We isolated the most active compound, referred to VD-3, from the dichloromethane extract of KM. The VD-3 was shown to be less cytotoxic to normal cells (murine splenocytes). From the identification of the chemical structure of VD-3 by spectral data and chemical synthesis, the compound was proven to be epi-oleanolic acid. Tumor cells treated with VD-3 showed a typical pattern of apoptotic cell death, such as apparent morphological changes and DNA fragmentation. These results indicate that epi-oleanolic acid is an important compound responsible for antitumor activity of KM.

Animals↗
PubMed2006

[Influence of ML-1 standardized mistletoe extract on the quality of life in head and neck cancer patients].

BACKGROUND: ML-1 standardized mistletoe extracts have been recommended for increasing the health-related quality of life in cancer patients. PATIENTS AND METHODS: The EORTC questionnaire QLQ-C30((V2)) was given to a randomly chosen subgroup of 399 patients of a prospective, randomized, open, multi-center trial. A total of 200 patients from this trial were randomized for ML-1 treatment (1 ng/kg body weight ML-1 was injected subcutaneously twice weekly over a 60-week period. Treatment cycles of 12 weeks were followed by a break of 4 weeks (between weeks 12-16, 28-32, and 44-48)). The remaining 199 patients formed the control group. RESULTS: Patients completed questionnaires before the start of their treatments at week 0 and continued until week 156. The compliance rate was high: 3611 questionnaires were available, which equals a median of nine longitudinal measurements per patient between weeks 0 and 156. Analysis did not indicate any improvement in the quality of life for either group. A significant decrease in quality of life, however, was seen in patients undergoing radiotherapy. In these patients, the global state of health was reduced and four symptom scales were significantly worse. CONCLUSION: Our results demonstrated no improvement in the quality of life in head and neck cancer patients when treated with ML-1 extract.

Adult↗
PubMed1988

Similarity of protein conformation at low pH and high temperature observed for B-chains of two plant toxins: ricin and mistletoe lectin 1.

A comparative study of subunits of two plant toxins, ricin (RC) and mistletoe lectin 1 (ML 1), has been undertaken. The study suggests that isolated B-chains of these toxins undergo structural transitions at low pH (from 5 to 4) and high temperature (45 degrees C), and as a result of the guanidine hydrochloride denaturing effect (to 3 M). Our results indicate that the protein conformation observed at low pH and high temperature are similar, though not identical. These conformations differ from the native one (pH 7, 25 degrees C), the protein in these conformations has a low fluorescence tryptophan intensity, and tryptophans are more exposed to aqueous solutions. However, these conformations differ also from the state unfolded by guanidine hydrochloride. An assumption is made that the partially denatured protein structure, exhibited at low pH and high temperature, is a functionally essential intermediate state of the toxin B-chain.

Hydrogen-Ion Concentration↗
PubMed1988

The site of action of the A-chain of mistletoe lectin I on eukaryotic ribosomes. The RNA N-glycosidase activity of the protein.

The site of action of the A-chain of mistletoe lectin (ML-A) from Viscum album on eukaryotic ribosomes was studied. Treatment of rat liver ribosomes with ML-A, followed by treatment of the isolated rRNA with aniline, caused the release of a fragment with about 450 nucleotides from 28 S rRNA. Further analysis of nucleotide sequences of this fragment revealed that the aniline-sensitive site of phosphodiester bond was between positions A-4324 and G-4325 in 28 S rRNA. These results indicate that ML-A inactivates the ribosomes by cleaving a N-glycosidic bond at A-4324 of 28 S rRNA in the ribosomes as ricin A-chain does.

Animals↗
PubMed1989

Selective killing of human monocytes by an immunotoxin containing partially denatured mistletoe lectin I.

The in vitro activity of an immunotoxin (IT) prepared by conjugating the monocyte specific RoMo-1 monoclonal antibody and partially inactivated Mistletoe lectin I (dMLI) containing inactivated B chain has been initially characterized. It is shown that while not affecting other mononuclear cells viability, this IT is capable of selectively destroying human monocytes after 24 h exposure thus resulting in the abrogation of monocyte support for PHA reactivity in mononuclear cell preparations. Therefore it seems to be possible to use this non-sugar binding holotoxin for immunotoxin preparation.

Antibodies, Monoclonal↗
PubMed1991

Immunotoxin with mistletoe lectin I A-chain and ricin A-chain directed against CD5 antigen of human T-lymphocytes; comparison of efficiency and specificity.

Monoclonal anti-CD5 antibody was coupled to the enzymatically active subunit of plant toxin [either mistletoe lectin I (ML) or ricin]. The obtained conjugates proved to be selectively toxic to CD5-bearing target cells. The immunotoxin prepared from ML A-chain (MLA) was as toxic as native ML and approximately 80-fold more active than the corresponding conjugate with ricin A-chain (RTA). The comparative studies of the structural properties of isolated MLA and RTA were carried out using intrinsic fluorescence spectroscopy. The results showed similar properties for both proteins. No antigenic cross-reactivity against both toxins was detected when using polyclonal antibodies. The results suggest that MLA-antibody conjugates may be potential candidates for therapeutical use.

Antigens, CD↗
PubMed2006

Interleukin-12 is associated with the in vivo anti-tumor effect of mistletoe extracts in B16 mouse melanoma.

Viscum album (VA) preparations consist of aqueous extracts of different types of lectins of mistletoe. VA exert cytotoxic and immunomodulatory properties that may be relevant for the inhibition of tumor growth. We addressed the effects of VA preparation VA Qu FrF on growth of B16F1 melanoma implanted in mice and on proliferation and cytokine synthesis of splenocytes. In C57BL6 mice, inhibition of tumor growth by VA was associated with an enhancement of splenocyte proliferation and with an up-regulation of IL-12 secretion. In IL-12-deficient strain of mice the inhibition of melanoma growth by VA and the splenocyte proliferation were abrogated. Results from the present study strongly suggest a crucial role of IL-12 in the anti-tumor properties of VA extracts.

Animals↗
PubMed2005

Evaluation of the hypoglycemic effect and antioxidant activity of three Viscum album subspecies (European mistletoe) in streptozotocin-diabetic rats.

The acute hypoglycaemic effect of water and ethanolic extracts of three Viscum album subspecies, ssp. album, ssp. austriacum, ssp. abietis, were investigated in normoglycaemic and streptozotozocin-induced diabetic rats. Blood glucose level was measured according to glucose oxidase method. The antioxidant activity of these extracts was also studied in the liver, kidney and heart tissues of streptozotocin-induced diabetic rats after subacute administration. In order to determine antioxidant activity of extracts, tissue MDA and GSH levels were measured by using spectrophotometric methods. All results were compared with the diabetic control groups. The findings obtained in the experiments demonstrated that European mistletoe (Viscum album L.) subspecies possess potent antihyperglycaemic and antioxidant activity depending on host plant.

Administration, Oral↗
PubMed2006

Improvement of an enzyme linked lectin assay to determine recombinant mistletoe lectin I.

Extracts from Viscum album leaves, with mistletoe lectin I (ML I) as the main therapeutic agent, are commonly used as an immunomodulating adjuvat in tumour therapy. Because of its popularity against cancer and the possibility for a better standardisation a recombinant ML I (rML I) was developed by Eck et al. To improve the sensitivity of an already established enzyme linked lectin assay (ELLA) for rML I human haptoglobins with different phenotypes (1.1, 2.1 and 2.2) are used to replace asialofetuin as matrix. To determine the carbohydrate binding specificity of the tested glycoproteins the ELLA was realised in the presence of the competitive carbohydrate beta-d-lactose. It could be shown that using haptoglobin phenotype 1.1 instead of asialofetuin improved the test results markedly. Both, the limit of detection and the limit of quantitation were decreased by an order of magnitude. However, this positive result was obviously accompanied by a loss in specificity of the test. The specificity of asialofetuin for rML I is almost six-fold higher than for the tested haptoglobins. Thus, in cases where high specificity and less sensitivity values for rML I is required the ELLA should still be run with asialofetuin as binding partner.

Antineoplastic Agents, Phytogenic↗
PubMed1998

Mistletoe lectin I forms a double trefoil structure.

The quaternary structure of mistletoe lectin I (MLI), a type II ribosome inactivating protein, has been determined by X-ray crystallography. A definitive molecular replacement solution was determined for MLI using the co-ordinates of the homologue ricin as a search model. MLI exists as an [AB]2 dimer with internal crystallographic two-fold symmetry. Domain I of the B chains is non-covalently associated through interactions involving three looped chains (alpha, beta, gamma) in each molecule of the dimer, forming a double trefoil structure. The ricin molecule which shares 52% sequence homology with MLI has a disulphide bridge between Cys20 and Cys39 in the alpha loop. An evolutionary mutation has replaced Cys39 with serine in MLI. This mutation appears to allow the alpha loop the flexibility required to take up its place at the dimer interface, and also suggests a rationale for why ricin does not form dimers. Measurement of retention times using FPLC gel filtration confirms that dimerisation also occurs in solution between MLI B chains with an association constant Ka = 10(6) M.

Amino Acid Sequence↗
PubMed2002

The cytotoxic effect of mistletoe lectins I, II and III on sensitive and multidrug resistant human colon cancer cell lines in vitro.

Multidrug resistance glycoprotein1 (MDR-1) eliminates amphiphilic chemotherapeutic agents out of tumour cells leading to therapeutic failures. The aim of this study was to investigate the cytotoxic effect of mistletoe lectins (MLs) I, II and III on the sensitive human colon cancer cell line HT 29(mdr-), its multidrug resistant variant HT 29(mdr+), the variant HT 29(SF1m) transfected with the MDR-1 gene and its sensitive control cell line HT 29(deltaSF). Both cell proliferation and ML binding pattern were analysed. Marked quantitative differences concerning the cytotoxic effect of the three MLs on the different cell lines were observed. All MLs showed the greatest cytotoxicity towards the HT 29(mdr+) cells, in which multidrug resistance (MDR) was induced by increasing concentrations of a MDR inducing agent. In contrast, MDR-1 and mock-transfected cells showed almost the same sensitivity towards the three MLs as the control cells (HT 29(mdr-)). FACS analysis showed that the HT 29(mdr+) cells were the cells with the highest density of ML binding sites. Thus, higher sensitivity of HT 29(mdr+) cells are not caused by the overexpression of MDR-1, but are caused by the general changes of the cellular glycosylation during the acquisition of the MDR phenotype.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2003

Immunobiological features of the galactoside lectin L-Lc isolated from the Argentine mistletoe Ligaria cuneifolia.

Ligaria cuneifolia has been used in Argentine folk medicine and is currently employed as substitute for the European mistletoe (Viscum album) as hypotensor agent. Extracts from V. album are widely used in cancer therapy and the antineoplasic effect is attributed to their cytostatic/cytotoxic and immunomodulatory actions. When studying immunomodulatory effects of L. cuneifolia extracts (Lc extracts), they inhibited proliferation of murine mitogen-activated lymphocytes, leukaemic lymphocytes (LB) and breast tumour cells (MMT). The aim of this work was to isolate and identify lectins from Lc extracts and investigate their immunobiological actions. A galactoside lectin (L-Lc) of 57 kDa was isolated. A polyclonal antiserum obtained against Lc extract recognised both L-Lc and MLI (V. album lectin), suggesting the possibility of shared epitopes. Treatment of LB tumour cells with L-Lc (0.01 and 0.1 microg/ml) produced up to 40.0+/-6.9% inhibition of cell growth, which seems partly mediated by apoptosis (apoptosis of L-Lc treated cells 58.4+/-10.3% versus non-treated cells 38.1+/-8.8%; P<0.05), analysed by acridine orange and ethidium bromide staining. Inhibitory effect on ConA stimulated splenocyte growth was non-significant, while a mitogenic effect was observed on normal murine splenocytes and MMT cells. L-Lc in non-cytotoxic concentrations (250 ng/ml) modified mRNA expression of IL-10 but neither that of TGF-beta nor of IL-2 produced by LB cells. In addition, 43.9+/-0.5% reduction in NO production by LPS-stimulated murine macrophages was found. Finally, survival rates of LB tumour-bearing mice treated or not with Lc extract or L-Lc failed to show significant differences.

Adjuvants, Immunologic↗