Synergistic Effects of Adjuvants Interferon-γ 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.

Induction of alkaline phosphatase in the inflamed intestine: a novel pharmacological target for inflammatory bowel disease

This study demonstrates the upregulation of alkaline phosphatase and the mechanisms involved in experimental colitis. All models of ileal and colonic inflammation examined, which were characterized by significant oxidative stress and neutrophil infiltration, resulted in an increase in alkaline phosphatase activity which was attributable to both epithelial cells and cells of the lamina propria, mainly leukocytes. The increase in alkaline phosphatase sensitivity to the inhibitors levamisole and homoarginine, together with changes in the apparent molecular size and in the sialization of the enzyme, indicated a change in the isoform expressed. An increase in tissue non-specific alkaline phosphatase expression was observed by Western blotting. Treatment with the bone/kidney alkaline phosphatase inhibitor levamisole or a monoclonal antibody resulted in significant protection from colonic inflammation. Taken together, these results indicate that the kidney isoform is a marker of intestinal inflammation and that it might even constitute a target for pharmacological intervention.

Total serum immunoglobulin M levels are affected by immunomodulators in seabream (Sparus aurata L.)

Immunoglobulin M (IgM) is a major component of the teleost humoral immune system. Despite the significance of IgM levels as an immune parameter, there are relatively few studies on changes induced in its total levels in serum. This study examines the effects of several immunomodulators (vitamin A, chitin, yeast cells or levamisole, which act as immunostimulants, and crowding, hypoxia or anaesthetics, which act as stressors) upon the total serum IgM levels of non-immunized gilthead seabream (Sparus aurata L.). Total serum IgM levels of fish fed with the assayed immunostimulant-supplemented diets were statistically higher than those in fish fed a non-supplemented diet, especially in the case of levamisole. On the other hand, serum IgM levels of fish subjected to different stressors were not affected by crowding, hypoxia or certain anaesthetics. However, benzocaine and a narcotic dose of 2-phenoxyethanol provoked a great reduction, while quinaldine sulphate increased IgM levels to a significant degree. These results show how the seric IgM levels can be differently affected by some immunomodulators and the important role they may play in the regulation of total circulating IgM levels in seabream. The possibility of using total serum IgM for assessing immunostimulation, disease diagnosis and stress symptoms during fish farming is discussed.

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.

Is oral levamisole immunostimulation in rats mediated by reduced levels of free plasma corticosterone?

A brief review of the immunostimulative and anti-inflammatory properties of levamisole is followed by a research report which indicates that in rats under antigenic challenge by ovalbumin, oral levamisole (18 mg/kg) decreases corticosterone levels. This previously unreported finding may belie the immunostimulative effect of levamisole.

Levamisole and its influence on the immune response of lambs

Ten parasite-free lambs were drenched with 8 mg/kg of levamisole on days 0 and 28 and were injected with human erythrocytes and ovalbumin one day after each drench. Ten other antigen-injected lambs were not drenched with anthelmintic as controls. Lymphocytes from the control and drenched lambs were cultured in vitro with RPMI 1640 plus 5% fetal calf serum (FCS), with 50% autologous serum only, with concanavalin A (Con A) or with phytohaemagglutinin (PHA). Decreased blastogenesis was observed in cells from the drenched lambs cultured in the presence or absence of mitogen and was most obvious when 50% autologous serum was used, particularly with PHA, and when lymphocytes were collected 3 and 7 days after the first and 3 days after the second antigen injection. There were no significant changes in antibody titres between the groups. Decreased serum complement activity was seen 3 days after the second antigen injection in the drenched lambs. Although there was a significant reduction in the serum insulin-like growth factor I levels 4 days after each levamisole drench, the drenched lambs gained significantly more weight than the non-drenched control lambs.

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.

Preliminary development of a live drug-controlled vaccine against bovine babesiosis using the Mongolian gerbil, Meriones unguiculatus

This study investigated the practicality and potential of the gerbil, Meriones unguiculatus, as a source of live Babesia divergens vaccine and also as a model for the use of the vaccine in cattle. A series of experiments with gerbils concerning vaccine infectivity, immunogenicity and safety were carried out. It was concluded that the use of RPMI medium/40% foetal calf serum as a diluent improved vaccine infectivity, but that the parasitaemia of the blood obtained from donor gerbils had little or no effect. The immunostimulants levamisole and killed Corynebacterium parvum improved vaccine immunogenicity and it was also shown that the subcutaneous route of infection resulted in the greatest host response. Control of vaccine virulence with drugs was only possible when drugs with prophylactic properties, such as imidocarb and long-acting oxytetracycline, were used. More studies are required on all these topics, particularly with regard to their applicability to cattle, and also concerning the possible attenuation of the parasite by manipulation in the gerbil host.

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.

Enhancement of the Arthus reaction and suppression of delayed type hypersensitivity (DTH) by pluronic F-68, a detergent frequently used to prepare perfluorocarbon emulsions

The effect of a 20% w/v RM101 (perfluorobutyltetrahydrofuran) emulsion containing 5% w/v of the detergent Pluronic F-68 or 5% w/v Pluronic F-68 given alone on the Arthus reaction and on delayed type hypersensitivity (DTH) were evaluated in female A/J mice. The test substances were administered i.v. at 1% body weight at 0,4,7,14 and 28 days prior to the i.p. immunization with 10(7) sheep red blood cells (SRBC). The increase in footpad swelling at 4 h (Arthus reaction) and at 24 h (DTH) after elicitation with the s.c. administration of 10(8) SRBC into the left footpad was used to assess immune competence. Pluronic F-68 given alone enhanced the Arthus reaction only when administered on day 0 of immunization. Pluronic F-68 given alone, as well as the perfluorocarbon emulsion containing Pluronic F-68, suppressed the 24 h DTH for as long as 4 days prior to immunization. Nonemulsified perfluorocarbon, on the other hand, had no effect on either the Arthus reaction or on DTH. The immunostimulatory agent, levamisole, administered (10 mg/kg i.p.) 1.5-2 h prior to immunization with SRBC counteracted both the Arthus reaction and the DTH response produced by Pluronic F-68. The present data clearly demonstrate that the changes in Arthus reaction and the DTH response are due to the Pluronic F-68 used to emulsify the RM101 perfluorocarbon; the changes induced by the detergent in these two immune parameters probably involve separate mechanisms.

[Immunogenic properties of the liposomal form of the rabies vaccine]

The liposomal form of inactivated cultural whole-virion rabies vaccine was shown to induce formation of more intensive immunity than the vaccine without liposomes. These data have been obtained in immunity challenge by intracerebral inoculation of fixed virus as well as intramuscular inoculation of street rabies virus.

Potentiation of interleukin-2 activity by levamisole and imidazole

Levamisole, a known antihelminthic drug, was able to affect IL-2 dependent proliferation of several T lymphocyte clones. Although levamisole did not replace IL-2 and had no effect at saturating IL-2 concentrations, it reduced by 2- to 4-fold the dose of IL-2 required to give 50% of the maximal DNA synthesis, the optimal concentration of levamisole being between 1 to 3 X 10(-4) M. This effect of levamisole was not due to an alteration of the kinetics of thymidine incorporation. Imidazole and other imidazole ring containing compounds, but not thiol-containing compounds, had similar effects to those of levamisole, suggesting a role of the imidazole ring in the potentiation of IL-2 activity.

Behaviourally conditioned modification of T cell subset ratios in rats

Levamisole injection resulted in an elevation in the T helper:T suppressor (H:S) subset ratio in rats at 24 h after injection due to a selective depression in the cytotoxic/suppressor subset. This response was shown to be conditionable and could be reenlisted 14 days later by re-exposure to the conditioned stimulus. Rats were conditioned using a taste aversion paradigm by pairing levamisole injection with the novel taste of saccharin. Fourteen days later, after a second exposure to saccharin without levamisole injection, H:S ratios were elevated in the blood of these rats compared to control rats injected with levamisole but fed normal water or rats fed saccharin without levamisole injection.

[Therapy of myocarditis with levamisole]

The influence of levamisole on the course of myocarditis was investigated. It was found that levamisole decreased the intensity of subjective symptoms of disease as well as normalised electrocardiographical and immunological changes in greater part of patients.

[Immunomodulating action of levamisole in influenzal infection in mice]

The time of the activation of the regulatory lymphocyte subpopulation in the spleen and the influence of levamisole on the course of influenza infection in mice were studied in parallel. The study revealed that the final effect of the immunomodulating action of levamisole was determined by the concrete phase of the regulatory activity of lymphocytes. At the same time the injection of the preparation at the peak of helper activity induced a transitory decrease in antibody formation and, in the fatal form of the infection, a rise in the death rate among the animals. The probable role of levamisole-activated macrophages in the transitory suppression of immune response in mice during influenza infection is discussed.

[Immunomodulating action of levamisole in its combined use with influenza vaccines]

The immunomodulatory effect of levamisole used in combination with influenza vaccines was studied in young and senile subjects. Levamisole activated antibody production in young subjects in response to administration of a live influenza A (H3N2) vaccine and enhanced the protective effect of vaccinations. The senile subjects vaccinated with inactivated influenza A vaccine (H3N2 and H1N1) had a good immune response and the use of levamisole was not reflected in antibody rises. At the same time, levamisole alone stimulated antibody production to influenza A and B viruses which might be due to irritation of immunocompetent cells carrying "immunological memory".

[Effect of levamisole on the B immunity system indices of erysipelas patients]

When used for the treatment of patients with different clinical forms of erysipelas, levamisole induced a significant decrease in the B-lymphocyte level in the peripheral blood and the concentration of IgG and IgA, previously elevated.

Levamisole exacerbates coxsackievirus B3-induced murine myocarditis

Levamisole administration to several strains of adolescent mice at the time of or up to 4 days post-inoculation (p.i.) with a myocarditic variant of coxsackievirus B3 (CVB3m) increased the number of myocarditic lesions above that found in CVB3m-inoculated mice. Virus replication in heart tissues in vivo was not affected by levamisole administration to the mice, nor was production of neutralizing antibody to CVB3m. Lymphocytes from nodes of virus-inoculated mice treated with levamisole at 2 days p.i. exhibited an increased reactivity to phytohemagglutinin on days 6 and 8 p.i., compared with respective responses by nodal T lymphocytes from CVB3m-inoculated mice. Levamisole treatment of CVB3m-inoculated mice also increased the reactivity of splenic and peripheral blood T lymphocytes to phytohemagglutinin on day 8 p.i., but not day 6 p.i., compared with the respective responses by lymphocytes from CVB3m-inoculated mice. The proportion of theta antigen-bearing lymphocytes in the total lymphocyte population in peripheral blood of CVB3m-inoculated mice was not altered by levamisole treatment. However, CVB3m-induced reduction in this subpopulation of lymphocytes in the nodes was restored to control levels by levamisole treatment. Reactivities of cytotoxic T lymphocytes from CVB3m-inoculated mice were increased against both normal and CVB3m-inoculated target cells after levamisole treatment of these mice. The results suggest that levamisole may contribute to CVB3m induction of myocarditis by several mechanisms, such as increasing the blastogenic activity of the phytohemagglutinin-responding subset of T lymphocytes, by possibly altering T-lymphocyte distribution in the body and by nonspecifically increasing reactivities of cytotoxic T lymphocytes.

[Effect of prodigiozan, levamisole and methyluracil on delayed hypersensitivity against a background of immunosuppressor use]

Immunostimulants, such as prodigiosan, levamisol and methyluracil, as well as their combinations with imuran, prednisolone or cyclophosphamide were studied for their effect on the delayed type hypersensitivity (DTH) induced by dinitrofluorobenzene alcohol solutions applied in challenge doses to the floor of the auricle of mice. It was shown that the immunostimulants did not affect the DTH in intact mice. In mice treated with imuran the DTH was significantly increased only by prodigiosan. Prednisolone used for a prolonged period before and after the sensitization and cyclophosphamide administered 24 hours before the sensitization increased the DTH. According to the literature data it was connected with T-suppressor inhibition. With the use of cyclophosphamide it was also connected with B-suppressor inhibition. Under such conditions the DTH was decreased to the control level by prodigiosan after the use of prednisolone or by levamisol after the use of cyclophosphamide. This was probably associated with increasing of the suppressor effect of the macrophages and activation of the T-suppressor effect by levamisol. Methyluracil had no effect on the DTH.

[Immunology - results of two decades of immunological research]

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.

Immune responses and immunostimulation in tuberculosis therapy

Despite a reasonably extensive literature on cellular and humoral immune responses in tuberculous disease, abnormalities tend to be secondary rather than predisposing to disease. No discrete immune deficiency or failure, which would explain the progression from non-infection to infection with Mycobacterium tuberculosis to tuberculous disease, has been identified. There is evidence that tuberculous disease occurs in a spectrum, analogous to leprosy, and it would seem that if immunostimulants, as adjuncts to standard therapy, are to be of any value in the treatment of tuberculosis, they should be used for non-reactive tuberculosis patients. The range of immunostimulants currently available tends to be indiscriminate in action and their targets in tuberculous disease largely uncertain; their role in therapy in discussed.

[Antitumor activity and the effect on immunogenesis of combinations of rubomycin and carminomycin with levamisole]

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.

[Nature of the disturbance of immune protection in diabetes mellitus and its correction with levamisole]

The number of T-rosette forming cells was shown to be reduced, T-lymphocytes functional activity decreased, and phagocytic activity depressed in patients with diabetes mellitus. This may point to weak immune response of the body and favor the development of bacterial complications in such patients. Levamisol stimulates the above immunity parameters in diabetic patients.

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.

[Effect of levamisole on lymphoid cells in vitro]

The paper is concerned with a study in the levamisole effect on lymphoid cells of bone marrow, thymus, spleen and lymph nodes of guinea pigs and CBA/mice. It is shown that levamisole stimulates the differentiation of immature bone marrow and thymus lymphocytes and restores the rosette-forming ability of thymocytes previously heated at 45 degrees C for an hour.