Synergistic effects of adjuvants interferon-gamma and levamisole on DNA vaccination against infection with Newcastle disease virus.

Both humoral and cell-mediated immune responses are important to protect animals from initial acute viral infection and establishment of chronic infection. Adjuvants for DNA vaccines can influence the balance between humoral and cell-mediated immunities. In this study, a DNA vaccine encoding the hemagglutinin-neuraminidase and fusion genes of Newcastle disease virus (NDV) incorporated with chicken interferon(provax-chIFN-gamma) cDNA as a molecular adjuvant and levamisole (LMS) as a chemical adjuvant was tested for its efficacy in protection against NDV lethal challenge. Compared with DNA vaccine alone, the DNA vaccine with provax-chIFN-gamma plus LMS induced significantly higher humoral and cell-mediated responses, as shown by higher levels of hemagglutination inhibition (HI) titers and T cell proliferation. In addition, the DNA vaccine with provax-chIFN-gamma plus LMS formulation increased the expression of IFN-gamma, interleukin (IL)-2, IL-4, IL-12, and IL-13, suggesting that the effectiveness of the IFN-gamma and LMS formulation is partly due to the enhancement of balanced cytokine production. Furthermore, the two adjuvants yielded 80% protection in chickens against challenge with a lethal dose of the virulent NDV strain. This study demonstrates that the synergistic effects of provax-chIFN-gamma plus LMS as the adjuvants in NDV DNA vaccination could be used to improve protective efficacy in chickens.

Levamisole is a potent enhancer of gilthead seabream natural cytotoxic activity.

Gilthead seabream (Sparus aurata L.) head-kidney (HK) leucocytes were incubated with 10(3) to 10(-4) ng levamisole/ml for 4, 24 or 48 h and then assayed for their natural cytotoxic activity against xenogeneic tumor cells. This activity was slightly increased after 24 h of incubation. In a second experiment, fish specimens were fed 0, 75, 150 or 300 mg levamisole/kg diet for 10 consecutive days. The fish were then fed a commercial non-supplemented diet and sampled 0, 1, 2, 3, 4 and 6 weeks post-administration of levamisole. The cytotoxic activity was found increased along the experiment and remained greatly enhanced at the end. In conclusion, levamisole enhanced seabream natural cytotoxic cell activity both in vitro and in vivo and had a great and lasting action when administered by feeding.

Immunologic effects of levamisole in mice and humans: evidence for augmented antibody response without modulation of cellular cytotoxicity.

Selected immunomodulatory effects of levamisole were studied in patients with asymptomatic metastatic colon cancer and in a preclinical model (CF1 female mice treated with methyl-azoxymethanol acetate) for colon tumors. In the patient population studied, there was no augmentation of cellular cytotoxicity or alteration in lymphocyte subpopulations that participate in these functions. An increase in Fc receptor binding on circulating monocytes was apparent at the 4-week timepoint; however, a corresponding increase in antibody-dependent cellular cytotoxicity was observed in only one of the six patients studied. In most patients, cellular cytotoxicity diminished with time. No significant effects on cellular immunity or carcinogenesis were observed in our murine studies. However, treatment with levamisole did increase circulating immunoglobulin levels and IgM response in mice immunized with the T-dependent antigen keyhole limpet hemocyanin. This parameter was not tested in the human trial. Failure to demonstrate antitumor effects on cellular immunity by levamisole in both human and murine studies suggests that these effects, if they do exist, may involve immunological parameters that were not tested using our methods or that may not be apparent in patients with more advanced malignancy.

Levamisole, the story and the lessons.

The history of the use of levamisole in man is summarized, from its start as an anthelmintic in the early sixties, through its world-wide recognition as an immunotropic agent especially in the seventies and early eighties, and its return to clinical prominence in 1989-90 as an effective adjuvant treatment for operable colon cancer. The knowledge accumulated from experimental tumour models and from clinical use in various types of cancer, supplemented with the recent evidence obtained from large-scale controlled trials in resectable colon cancer is reviewed. It is speculated that we may not have seen the end of levamisole story yet; also, the role of serendipidity in drug research is emphasized.

Levamisole in the adjuvant treatment of colon cancer.

The chemistry, pharmacology, pharmacokinetics, assay methodologies, adverse effects, and dosage of levamisole are described, and the clinical studies of levamisole therapy in patients with colorectal carcinoma are reviewed. Levamisole is a synthetic, orally active agent that has antihelmintic and immunomodulatory properties. It is capable of inducing T-cell differentiation and restoring depressed effector functions of peripheral lymphocytes and phagocytes to normal. The drug is well absorbed from the gastrointestinal tract after oral administration and is extensively metabolized by the liver. Gas chromatography and high-performance liquid chromatography are the most common methods used to measure concentrations of levamisole in biologic fluids. Levamisole combined with fluorouracil has been associated with a one-third reduction in recurrence and risk of death in patients with surgically resected Dukes stage C colon cancer; this combination is now recommended as standard therapy in these patients. Uses in patients with rectal carcinoma, Dukes stage B colon cancer, metastatic colon cancer, other malignancies, or nonmalignant disorders remain investigational. Common adverse effects include nausea, abdominal pain, vomiting, diarrhea, metallic or altered taste, flulike symptoms, mood elevation, insomnia, hyperalertness, dizziness, and headache. The most serious adverse effect associated with levamisole is granulocytopenia. The FDA-approved dosage of levamisole is 50 mg orally every eight hours for three days every two weeks. Levamisole therapy is to be initiated no earlier than 7 and no later than 30 days after surgery and is to be continued for one year. Levamisole combined with fluorouracil has been associated with a one-third reduction in recurrence and risk of death in patients with resected stage C colon cancer. Further research is needed to more clearly define the mechanism of action, optimum dose and scheduling, and clinical efficacy of levamisole in treating other malignancies.

Levamisole--biological response modifier in Taenia crassiceps--mouse experimental system.

Levamisole, a common anthelminthic preparation, was used for the modification of the immune response of mice to vaccination with soluble antigen from Taenia crassiceps. The combination of antigen with Levamisole significantly increased the immunogenic effect of the antigen. Metacestodes survived in 16.7% after one dose and in 42.9% after two doses of Levamisole. The percentage of resistance was 97.7% and 67.8%.

[Immunology - results of two decades of immunological research]. / Immunologie - oogst van twee decennia immunologisch onderzoek.

The discipline of immunology has made very rapid progress during the past twenty years. A general introductory part was followed by a discussion of immunological components in resistance. Subsequently, the importance of controlling the immunological system was stressed. The significance of the network theory was briefly referred to. Attention was then drawn to specific and non-specific stimulation of the immune response, which are essential both in theory and in actual practice. A number of instances are cited to illustrate these features in recent developments in the fields of preparation of vaccines and immunological treatment of cancer. It was pointed out that, during the past decades, the discipline of immunology not only made great strides in the field of human medicine and experimental animal models associated with this branch of medicine but also in that of veterinary medicine. It was predicted that immunology would also continue to be essential in the diagnosis, treatment and prevention of disease in animals.

[Antitumor activity and the effect on immunogenesis of combinations of rubomycin and carminomycin with levamisole]. / Izuchenie protivoopukholevoi aktivnosti i vliianiia na immunogenez kombinatsii rubomitsina i karminomitsina s levamizolom.

The antitumor activity and effect on immunogenesis of rubomycin and carminomycin combinations with levamisole were studied comparatively. It was found that levamisole administered after carminomycin increased the intensity of delayed hypersensitivity in mice and only partially reduced immunoreactivity of the animals estimated by the number of antibody-forming cells in the spleen. No such effect was observed after injections of rubomycin. The antitumor effect of the combinations of the antibiotics wit levamisole was studied in experimental transplantable mouse lymphosarcoma L10-1. The use of rubomycin or carminomycin in combination with levamisole increased the survival of the animals and sometimes resulted in complete resolution of the tumors. No such effect was observed in treatment of the animals with the drugs alone. The data are indicative of a possible use of levamisole in combination with antitumor antibiotics in immunochemotherapy of tumors.

Cellular immune modulation after a single high dose of Levamisole in patients with carcinoma.

The effect of a single high dose of Levamisole (200 mg/M2) on delayed-type hypersensitivity (DTH) in vivo and on lymphocyte blastogenesis to mitogens and antigens in vitro was studied in 26 patients with carcinoma. Similar studies were conducted in 24 control patients. Levamisole had a moderate but significant enhancing effect on DTH to Dermatophytin detectable no earlier than eight hours and still present at 48 hours after the drug administration. A moderate but significant enhancing effect on lymphocyte blastogenesis to mitogens and antigens was also demonstrated during the same time sequence. Further clinical trials with Levamisole should be conducted with more attention paid to schedule of drug administration.

Levamisole-associated neutropenia and autoimmune granulocytotoxins.

To investigate possible immune mechanisms responsible for levamisole-associated neutropenia we tested patients with bladder cancer on levamisole therapy. Autoimmune and complement-dependent granulocytotoxic antibodies were detected in 3 patients with levamisole-induced neutropenia. The granulocytopenia appeared to be causally related to the presence of autoantibodies in that pretreatment serum or serum obtained after the restoration of neutrophil counts showed diminished or no granulocytotoxic reactivity. In addition, granulocytotoxins were found in 6 out of 20 (30%) patients receiving levamisole compared to only 2 out of 28 (7.1%) patients on no levamisole or placebo (P less than 0.06). Hence, screening for granulocytotoxins may forewarn of neutropenia in patients receiving levamisole for a variety of clinical diseases.

Combination of levamisole immunotherapy and polychemotherapy in advanced breast cancer.

In a randomized double-blind study, 101 female patients with breast cancer treated with Adriamycin chemotherapy in combination with vincristine and cyclophosphamide received either levamisole immunotherapy or placebo. The investigation was preceded by a pilot study involving 44 patients, of whom 25 received levamisole; the intermittent four-drug schedule of cyclophosphamide, vinblastine, methotrexate, and 5-fluorouracil, however, formed the basis of chemotherapy. In both studies, levamisole increased the response rates (P = 0.03), and in the present controlled trial it also significantly lengthened survival (P = 0.05). The results correlated with initial and levamisole-induced improvement of cell-mediated immunity.