Thymus-like activities of sulphur derivatives on T-cell differentiation

The biological activity of bispecific trastuzumab/pertuzumab plant biosimilars may be drastically boosted by disulfiram increasing formaldehyde accumulation in cancer cells

Studies of breast cancer therapy have examined the improvement of bispecific trastuzumab/pertuzumab antibodies interacting simultaneously with two different epitopes of the human epidermal growth factor receptor 2 (HER2). Here, we describe the creation and production of plant-made bispecific antibodies based on trastuzumab and pertuzumab plant biosimilars (bi-TPB-PPB). Using surface plasmon resonance analysis of bi-TPB-PPB antibodies binding with the HER2 extracellular domain, we showed that the obtained Kd values were within the limits accepted for modified trastuzumab and pertuzumab. Despite the ability of bi-TPB-PPB antibodies to bind to Fcγ receptor IIIa and HER2 oncoprotein on the cell surface, a proliferation inhibition assay did not reveal any effect until α1,3-fucose and β1,2-xylose in the Asn297-linked glycan were removed. Another approach to activating bi-TPB-PPB may be associated with the use of disulfiram (DSF) a known aldehyde dehydrogenase 2 (ALDH2) inhibitor. We found that disulfiram is capable of killing breast cancer cells with simultaneous formaldehyde accumulation. Furthermore, we investigated the capacity of DSF to act as an adjuvant for bi-TPB-PPB antibodies. Although the content of ALDH2 mRNA was decreased after BT-474 cell treatment with antibodies, we only observed cell proliferation inhibiting activity of bi-TPB-PPB in the presence of disulfiram. We concluded that disulfiram can serve as a booster and adjuvant for anticancer immunotherapy.

Influence of levamisole and other angiogenesis inhibitors on angiogenesis and endothelial cell morphology in vitro

Angiogenesis, the formation of new blood vessels from existing vessels is required for many physiological processes and for growth of solid tumors. Initiated by hypoxia, angiogenesis involves binding of angiogenic factors to endothelial cell (EC) receptors and activation of cellular signaling, differentiation, migration, proliferation, interconnection and canalization of ECs, remodeling of the extracellular matrix and stabilization of newly formed vessels. Experimentally, these processes can be studied by several in vitro and in vivo assays focusing on different steps in the process. In vitro, ECs form networks of capillary-like tubes when propagated for three days in coculture with fibroblasts. The tube formation is dependent on vascular endothelial growth factor (VEGF) and omission of VEGF from the culture medium results in the formation of clusters of undifferentiated ECs. Addition of angiogenesis inhibitors to the coculture system disrupts endothelial network formation and influences EC morphology in two distinct ways. Treatment with antibodies to VEGF, soluble VEGF receptor, the VEGF receptor tyrosine kinase inhibitor SU5614, protein tyrosine phosphatase inhibitor (PTPI) IV or levamisole results in the formation of EC clusters of variable size. This cluster morphology is a result of inhibited EC differentiation and levamisole can be inferred to influence and block VEGF signaling. Treatment with platelet factor 4, thrombospondin, rapamycin, suramin, TNP-470, salubrinal, PTPI I, PTPI II, clodronate, NSC87877 or non-steriodal anti-inflammatory drugs (NSAIDs) results in the formation of short cords of ECs, which suggests that these inhibitors have an influence on later steps in the angiogenic process, such as EC proliferation and migration. A humanized antibody to VEGF is one of a few angiogenesis inhibitors used clinically for treatment of cancer. Levamisole is approved for clinical treatment of cancer and is interesting with respect to anti-angiogenic activity in vivo since it inhibits ECs in vitro with a morphology resembling that obtained with antibodies to VEGF.

Levamisole Inhibits Angiogenesis in vitro and Tumor Growth in vivo

The synthetic anthelmintic compound Levamisole has previously been used in cancer treatment as an adjuvant in combination with 5-fluorouracil. Its mode of action remains unclear, but an immune-stimulatory effect has been suggested. Here, we show that Levamisole inhibits angiogenesis in vitro and tumor growth in vivo. In vitro, Levamisole specifically inhibits proliferation and differentiation of endothelial cells propagated in co-culture with fibroblasts. In vivo, Levamisole inhibits the growth in nude mice of a transplanted human tumor. The use of nude mice as tumor hosts permits the discrimination between the angiogenesis inhibitory effect of Levamisole and its assumed immune-stimulatory effect. Our findings support a possible therapeutic effect of angiogenesis inhibitors in the treatment of cancer and call for further investigations of the mechanism(s) underlying the anti-angiogenic effect of Levamisole.

Effects of thymomimetic drugs and zinc supplementation on the cellular immune response in hydrocortisone-suppressed mice

The studies were carried out on Balb/c mice (5-6 weeks of age) exposed to immunosuppression by a single intraperitoneal dose (125 mg/kg) of hydrocortisone. Prior to hydrocortisone injection the mice were treated with diethyldithiocarbamate (DTC) intra-peritoneally at a dose of 20 mg/kg, five times at 48 h intervals or calf thymus extract (TFX) at a dose of 10 mg/kg, 10 times at 24 h intervals. The two drugs were used per se or in zinc ions interactions, by adding zinc ions (as sulphate salt) to drinking water at a dose of 72 microg/mouse per day. The results obtained in the study show that hydrocortisone injection drastically decreases the number of thymocytes and splenocytes, which is also accompanied by a decreasing weight ratio of the thymus and spleen. The decreasing number of thymic and spleen cells corresponds to a decreasing percentage of CD4+, CD8+ and CD19+ splenocytes and double positive CD4+CD8+ thymocytes. Changes in the number of thymic cells affect their activity, which is expressed in a decreased proliferative response of thymocytes stimulated in vitro with concanavalin A (Con A) and phytohaemagglutinin (PHA). It has also been found that a single hydrocortisone dose decreases interleukin (IL)-1 production by murine intraperitoneal macrophages stimulated in vitro with lipopolysaccharide (LPS) from Escherichia coli. TFX or DTC counteract hydrocortisone-induced immunosuppression, which is expressed in partial normalization of the total number of thymic and spleen cells, accelerated regeneration of the two lymphatic organs, shorter suppressive action of hydrocortisone on the percentage of CD4+, CD8+ splenocytes and double positive (CD4+CD8+) and CD4+ thymocytes. Furthermore, total counteraction against the suppressive action of hydrocortisone to proliferative activity of thymocytes stimulated in vitro with Con A and PHA was observed. TFX administered prior to hydrocortisone injection partially prevented the suppressive action of the drug on IL-1 production by intraperitoneal macrophages, but such an effect was not observed with DTC. The immunorestorative effect of TFX and DTC was augmented by zinc supplementation. The results obtained in the study show that neither TFX nor DTC administration per se and in interaction with zinc supplementation were able to change the suppressive effect of hydrocortisone on the percentage of B splenocytes (CD19+ cells).

The effect of DTC on mitogen-induced proliferation of thymocytes in restrained mice. Comparison with calf thymus extract

The cardinal sign of acute stress is thymic involution, which subsequently attenuates the activity of immunocompetent cells, notably T-lymphocytes, macrophages and NK cells. Sodium diethyldithiocarbamate (DTC), a low molecular weight sulphur compound, may function as a thymic hormone to induce precursor cells to become functionally mature T-lymphocytes. The studies were conducted on Balb/c mice exposed to restraint stress twice for 12 h at 24 h intervals. DTC at a dose of 20 mg/kg or calf thymus extract (TFX) at a dose of 10 mg/kg were injected i.p. four times at 24 h intervals prior to the exposure. It has been found that restraint stress markedly reduces the number of thymocytes which is concomitant with reduction in the weight of the thymus. In our study the changes sustained for 10 days of the observation. Besides, alterations in proliferative response of the thymocytes stimulated in vitro with concanavalin A (Con A) and phytohemagglutinin (PHA) were observed. The proliferative response of thymocytes to Con A was reduced 24 h after the exposure to restraint stress, but between days 4 and 7 it was found at increased levels, which decreased again on day 10. In contrast, the proliferative response of thymocytes to PHA was depressed for the entire 10 day period of the observation. It has been found that DTC and TFX administered to mice prior to restraint stress successfully counteract stress-induced immunosuppression, albeit TFX exerts stronger protective and regenerating impact on the thymus than DTC. TFX totally inhibits the suppressive effect of stress on proliferative activity of the thymocytes stimulated in vitro with Con A and PHA, stimulates restoration of thymic cells and increases the weight of the thymus. In contrast, DTC is not able to counteract the decrease in proliferative response of thymocytes to PHA.

Effect of DTC on humoral response of SRBC-immunized mice exposed to restraint stress. Comparison with calf thymus extract

The studies were conducted on Balb/c mice exposed to restraint stress twice for 12 h at 24 h intervals. Some of the experimental mice were immunized i.p. with sheep red blood cells (SRBC). The antigen was injected before the first exposure of the mice to restraint stress, or immediately after the second loading was ended. Sodium diethyldithiocarbamate (DTC) at a dose of 20 mg/kg or calf thymus extract (TFX) at a dose of 10 mg/kg were injected i.p. four times at 24 h intervals, before or after the exposure to restraint stress. In our experiment restraint stress drastically reduced the number of thymocytes and splenocytes as well as the weight ratio of the thymus and spleen and the changes sustained for 10 days of the observation. Besides, humoral response of the restrained mice to SRBC was deteriorated, as the number of plaque forming cells (PFC) and anti-SRBC antibody titers (total and 2-mercaptoethanol resistant) decreased. The suppressive action of the stress on humoral response was weaker when the antigen injection preceded the first exposure of mice to restraint stress as compared with that observed when antigen stimulation took place immediately after the exposure of mice to stress. It has been found that DTC and TFX administered to mice either before or after the exposure to restraint stress effectively inhibit stress-induced immunosupression. The protective or immunomodulating action of the two drugs is expressed in accelerated and enhanced recovery of the spleen and thymus and in total or partial restoration of the humoral response to thymus-dependent antigen. TFX, administered after the exposure of mice to restraint stress, proves to have a stronger protective and reconstructive impact on thymus, while DTC has a stronger restoring effect on the humoral response dependent on effector T lymphocytes. DTC administered immediately after the exposure of mice to restraint stress results in total restoration of humoral response to SRBC.

Cyclosporine, FK-506, rapamycin, and other immunomodulators

Immunomodulatory agents represent a unique group of therapies that are not biologics and have relatively specific, noncytotoxic effects on the immune system. Cyclosporine has been the most widely tested of the immunomodulatory agents and shown efficacy in a variety of autoimmune diseases as well as monotherapy in established rheumatoid arthritis. FK-506 and rapamycin, agents similar to cyclosporine, are being tested in human transplantation, with only arthritis studies having been done in animals. Tilomisole, imuthiol, and mycophenolate mofetil have been studied in limited rheumatoid arthritis trials with positive effects. Although more specific and with manageable short-term side effects, this group of therapies requires more studies to establish their efficacy and long-term safety.

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.

T-cell adjuvants

T-cell adjuvancy involves the use of agents to stimulate preferentially delayed type hypersensitivity (DTH). Traditional adjuvants like Alum, Freunds, muramyl peptides, and endotoxins are not selective. Natural infection (e.g. vaccinia) may yield selective DTH. Low dose cyclophosphamide (CY) with mycobacteria was the first experimental T-cell adjuvant. New adjuvant formulations (ISCOMS, MAPS, etc.) with synthetic T-cell epitopes offer improved formulations. Upregulation of TH-1 helper cells and their actions with interleukins like IL-2, IL-12, and gamma IFN or antibodies to IL-4 and IL-10 may augment potently pathogen and tumor resistance. Similarly, transfection of tumor target cells with genes for IL-2, IL-12, gamma IFN, etc., offers novel vaccine treatment approaches. Finally, "thymomimetic" peptides like thymosin alpha 1 or drugs like levamisole or isoprinosine alone or in conjunction with interleukins may augment TH-1 and DTH responses. These approaches are seeing increasing emphasis in new treatment strategies for cancer and infections like HIV.

The use of immunomodulators in early rheumatoid arthritis

Immunomodulators represent a unique class of drugs that are not biologics, usually are isolated from nature, and have relatively specific noncytotoxic effects on the immune system. Although most slow-acting antirheumatic drugs (SAARDs) have effects on the immune system, these effects usually are not specific, often are cytotoxic, are not associated with specific cellular binding proteins, and their effect on immunity is difficult to correlate with their clinical effects. Most immunomodulators primarily affect T cells; because of their apparent role in rheumatoid arthritis (RA), studies of these agents are appropriate. Cyclosporine, the most widely tested of the immunomodulators, has shown significant efficacy in established RA in studies worldwide. However, only one study using cyclosporine has been performed in relatively early RA, in which the most positive effects might be expected. FK506 and rapamycin, agents similar to cyclosporine, are being tested in human transplantation; the only arthritis studies have been performed in animals. Tilomisole, imuthiol, and mycophenolate mofetil have been studied in limited RA trials, with positive effects. However, no trials have been conducted in early RA. Although promising, this class of drugs will require more studies to establish their efficacy and safety, especially in early RA.

Immunological properties of heterozygous nu/+ mice: changes in antibody response and inducibility of tolerance to protein antigens

Heterozygous nu/+ mice are not fully identical in their immunological properties with the mice of wild +/+ genotype. A colony of nu/nu, nu/+ and +/+ mice from the same breeding nucleus was established and their immune reactivity to human serum albumin, inducibility of adult immune tolerance to hen egg lysozyme (HEL), sensitivity of their lymphoid cells to stimulation by mitogens and ratio of CD3, CD4 and CD8 positive cell populations was studied. Both the numbers of antibody-forming cells in regional lymph nodes and the antibody titres in sera of nu/+ mice were highly variable, between undetectable values of nu/nu and high values of +/+ homozygotes. Intravenous pretreatment with soluble HEL, leading in +/+ mice to a deep hyporeactivity to subsequent immunization with the same antigen, did not decrease the response of nu/+ mice significantly. These results indicate that the immunological alteration of nu/+ mice is not only quantitative and that T cell subpopulations might be differentially modified by the presence of nu allele. The finding of decreased CD4:CD8 ratio in nu/+ mice also supports this idea.

The effect of DTC on humoral response restoration and thymocyte subpopulations in cyclophosphamide-immunosuppressed mice

The effects of sodium diethyldithiocarbamate (DTC) on humoral response to SRBC and restoration of the response impaired by a single cyclophosphamide dose (200 mg/kg) were tested on mice. Moreover, the effect of DTC (20 mg/kg) on thymocyte subpopulations was tested on non-immunized mice previously treated with cyclophosphamide. It was found that DTC (20 mg/kg) administered to the immunized mice enhanced humoral response to SRBC, which was reflected in the increased number of PFC and (7S) serum hemagglutinin titer. In contrast, partial restoration of the primary humoral response after DTC injection was observed in the mice administered a single cyclophosphamide dose. The effect of DTC was stronger after 6 days following cyclophosphamide injection, i.e. at the time when spontaneous restoration of T lymphocytes begins. In addition, it was found that DTC given to non-immunized mice treated with cyclophosphamide had a modulating effect on thymocyte subpopulations. Depending on the time of exposure to cyclophosphamide, DTC either increased the percentage of CD4 thymocytes or decreased the percentage of CD8, which subsequently led increased CD4/CD8 coefficient. DTC did not change the suppressing action of cyclophosphamide on the percentage of double-positive thymocytes.

Experimental modulation of IL-1 production and cell surface molecule expression by levamisole

Data from a variety of sources suggest that one target cell for levamisole might be the macrophage. Current results reveal that oral levamisole pre-treatment provides elicited peritoneal macrophages with the ability to respond better to ex vivo LPS stimulation, and that levamisole can directly act on LPS-stimulated macrophages in vitro, resulting in enhanced production of IL-1, a key mediator of the immune response. These data offer further biological and immunologic evidence that IL-1 production is indeed enhanced by levamisole. Finally, these phenomena were not confined to macrophages taken from mice given levamisole. Increased IL-1 expression was found to occur for cells treated in vitro with levamisole, demonstrating that there were direct effects by levamisole on LPS-stimulated macrophage cytokine production. IL-1 has been reported to have a number of direct and indirect anti-tumor effects which might be sufficient to provide localized protection against tumor invasion or growth in the adjuvant setting. The findings described above are therefore consistent with suggestions of an increased host response in certain types of cancer due to levamisole treatment, and are also consistent with reports of levamisole's providing a beneficial effect in other cases of immunodeficiency disease. Recent clinical data provided by Janik et al. demonstrate that levamisole administration caused increases in circulating levels of neopterin and soluble IL-2 receptor (sIL-2R). This in vivo result is consistent with in vitro data showing augmented IL-1 induction after levamisole treatment, since neopterin is a marker for macrophage activation and sIL-2R release correlates with IL-2 production and binding after IL-1 activation of T-cells. These data are therefore consistent with the hypothesis that levamisole can induce a macrophage-derived cytokine cascade which may have beneficial effects in host responses to human cancer. It is attractive to speculate that there may be increased cytokine expression in vivo (yet to be confirmed) which might contribute to the added clinical benefit when 5-FU is combined with levamisole. Data from nude mice bearing human tumor xenografts demonstrate improved antitumor responses to 5-FU in combination with levamisole, and it will be interesting to determine whether increased interferon, TNF, or other cytokines can be observed in this model. In addition, the ability of levamisole to increase ICAM-1 expression on certain tumor cell lines may be a mechanism by which similar cells are rendered more sensitive to host effector mechanisms in vivo.(ABSTRACT TRUNCATED AT 400 WORDS)

Dose response and timing effects in the therapy of the LP-BM5 murine retrovirus-induced lymphoproliferative immunodeficiency disease with diethyldithiocarbamate

Diethyldithiocarbamate (DTC) was used to treat the murine, retrovirus-induced, immunodeficiency disease (MAIDS). Once-weekly treatment was not effective and 800 mg/kg was toxic. When 200, 400 and 600 mg/kg were given i.p., 5 days per week, starting either on the day of virus inoculation or 14 days later, a dose-response and time-response relationship was noted. Higher doses and a 2-week delayed onset of treatment were generally more effective in reducing the development of lymphadenopathy, hypergammaglobulinemia and in prolonging survival than treatment started on the day of virus inoculation. When treatment was delayed until 10 weeks after virus inoculation existing lymphadenopathy was abrogated (treated node area 0 mm2 compared to control 175 mm2, P < 0.0001) and survival was improved (treated 100% compared to control 12.5%, P < 0.0001). However, when therapy was stopped animals died at the same rate as the untreated controls. These data indicate that DTC is active in MAIDS in a dose-responsive and time-dependent manner.

Sodium dithiocarb as adjuvant immunotherapy for high risk breast cancer: a randomized study

Sixty-four patients with non metastatic high risk breast cancer were randomized in a double blind trial of adjuvant immunotherapy with sodium dithiocarb (DDC) versus placebo. All patients underwent prior surgery (mammectomy according to Patey) then adjuvant FAC chemotherapy +/- DDC. With a median follow-up of 5 years we observed 6 relapses and 5 deaths in DDC group; 13 relapses and 12 deaths in control group. At 6 years, overall survival is 81% in DDC group versus 55%. Disease free survival (DFS) is 76% in DDC group versus 55%. DDC associated to chemotherapy and locoregional treatment can improve survival and probably DFS in this high risk breast cancer subgroup.

Ascaris suum--vaccination of mice with liposome encapsulated antigen

Vaccination with liposome encapsulated adult crude antigen with and without coencapsulated immunomodulator (levamisole) in a mice/larval Ascaris suum model provided protection against a challenge infection (2000 eggs) in mice immunised by immobilised antigen. The best results (88.9% protection) were obtained with a combination of two doses of liposome entrapped antigen with leamisole. Vaccination with liposome vaccine without modulator was slightly less effective (78.7% protection). A single dose of vaccine was ineffective (14.3% protection). Application of the soluble antigen without any adjuvants led to the enhancement of worm yield in lungs and liver.

Studies on tumor induced angiogenesis

Methods were developed to test angiogenic response to human tumor implants and various biologic agents in the cornea of rabbits and non-human primates (Macaca arctoides). Crude PDGF preparations were found to have significant angiogenic effect. Purified, recombinant PDGF preparations were also effective inhibitors (e.g. pentoxifylline (Px) (which also were found to release PgI2 and t-PA) inhibited human tumor implant induced angiogenesis and reduced spontaneous metastases in 3 transplantable murine tumors (Furth-Columbia Wilms' tumor in Furth-Wistar rats, C-1300 neuroblastoma in A/J mice and HM-Kim mammary carcinoma in Wistar rats) but not in the NIH adenocarcinoma in Balb/c mice. Sodium diethyldithiocarbamate (DDTC), a metal complexing agent with special affinity to copper and anti-thyroid as well as, immune stimulating activity was shown to be anti-angiogenic and to potentiate the effect of Px. The anti-fibrinolytic agents epsilon amino caproic acid (EACA) and tranaxamic acid (t-AMCHA) were anti-angiogenic. DDTC and Px were synergistic from this point of view.

Effective therapy of the LP-BM5 murine retrovirus-induced lymphoproliferative immunodeficiency disease with diethyldithiocarbamate

The effects of therapy with the immunomodulator diethyldithiocarbamate (DTC) on the manifestation and natural history of LP-BM5 murine retrovirus infection in adult C57 Black 6 mice was investigated. DTC itself, had limited effects on the spleen weight, serum IgM, or mitogen responses of the non-virus-infected control mice when evaluated over a 9-week period. The virus inoculum administered was such that there was approximately a twofold increase in serum IgM and a halving of phytohemagglutinin (PHA) and lipopolysaccharide (LPS) responses in about two weeks and death of all animals by about 26 weeks postinfection. Doses of DTC of 20 and 200 mg/kg weekly or 5 days per week (intraperitoneally) in mice with LP-BM5 infection did not alter the manifestations or course of the disease. Doses of 400 or 600 mg/kg given 5 days per week, starting either 2 weeks before or the day of virus inoculation significantly reduced hypergammaglobulinemia, spleen weight, lymphadenopathy, and also prolonged survival. A dose of 400 mg/kg started 2 weeks after virus inoculation resulted in partial prevention of hypergammaglobulinemia, splenomegaly, and lymphadenopathy as well as 100% survival compared with 12.5% in non-drug-treated controls at 23 weeks after virus inoculation. The 9 surviving animals in the treated group were then allocated to continue treatment or stop treatment. In the animals without further treatment, lymphadenopathy and mortality occurred starting within 6 weeks after cessation of therapy while the animals with continued treatment remained in good condition for 40 weeks. There was only a very limited and transient effect of DTC therapy on the decline of the proliferative responses to phytohemagglutinin or lipopolysaccharide in any of the treated groups in the above described experiments.(ABSTRACT TRUNCATED AT 250 WORDS)

Enhancement of in vitro lipopolysaccharide-stimulated interleukin-1 production by levamisole

The production of interleukin-1 (IL-1) by the P388D1 mouse macrophage cell line and by adherent peritoneal exudate cells (PMs) was examined. In vitro IL-1 production by P388D1 cells treated with lipopolysaccharide (LPS) was enhanced by coculture with levamisole (0.1 to 10 microM). Oral administration of levamisole (3 mg/kg) to mice also resulted in potentiation of in vitro IL-1 production by thioglycollate-elicited peritoneal macrophages in response to in vitro LPS stimulation. Potentiation was approximately twofold. IL-1 production in the absence of LPS by either the P388D1 cells or the PMs was nil, and levamisole did not directly stimulate IL-1 production in these cases. IL-1 activity in the culture supernatants was measured by thymocyte comitogenic assays. The immunochemical identify of the thymocyte comitogenic activity as IL-1 alpha was confirmed by neutralization with a specific goat anti-mouse IL-1 alpha antiserum. These results suggest that one mechanism by which levamisole acts to normalize and restore immune responses may be enhancing the signals which enable activated macrophages to secrete IL-1.

Sulphane sulphur in biological systems: a possible regulatory role

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A randomized, controlled dose response study of intravenous sodium diethyldithiocarbamate in patients with advanced human immunodeficiency virus infection

Sodium diethyldithiocarbamate (Imuthiol, DTC) has previously been observed to promote T-cell maturation in animal models and to reduce lymphadenopathy and improve survival in a murine AIDS model. In addition, several clinical studies have suggested that one dosage regimen may be active in patients with HIV infection. We conducted a randomized, controlled dose response study of intravenous DTC in patients with the acquired immunodeficiency syndrome (AIDS) and AIDS-related complex (ARC). Drug associated toxicities included gastrointestinal upset, burning at the infusion site, metallic taste, sneezing, confusional states, hyperactivity, delusional thinking, and myoclonus. Toxicity was ameliorated by dose reduction. The maximally tolerated dose varied for individual patients from 200 mg/m2 weekly to 800 mg/m2 twice weekly. No myelosuppression was observed. In patients with greater than 200 CD4+ cells/uL, a statistically significant reduction of lymphadenopathy occurred; whereas no beneficial effects were observed in patients with less than 200 CD4+ cells/uL. Improvement in symptom score and stabilization of CD4+ count also occurred in the treated group, although these trends did not reach statistical significance. Further controlled clinical trials of DTC in earlier HIV infection are warranted.

A pilot study of diethyldithiocarbamate in patients with acquired immune deficiency syndrome (AIDS) and the AIDS-related complex

We investigated the use of diethyldithiocarbamate (DTC, or Imuthiolr, Merieux Institute) as a therapeutic agent in patients with Acquired Immune Deficiency Syndrome (AIDS) and AIDS-Related Complex (ARC). Patients were prospectively stratified and randomized to receive DTC 200 mg/m2 intravenously weekly for 16 weeks or no therapy, followed by crossover to the opposite arm for an equal period. Forty-four patients were entered and forty were evaluable. There was a statistically significant decrease in symptoms in the DTC treated patients compared to the controls (p = .002). There was a significant improvement in lymphadenopathy in the treated patients compared to the controls (p = .005). One patient showed disappearance of splenomegaly, one clearing of antifungal agent-resistant perianal moniliasis, and one clearing of hairy leukoplakia. No significant differences in progression were noted. No changes were seen in any of the immunological parameters measured. There was no significant toxicity. Because of the changes in symptoms and in lymphadenopathy, we suggest that further study of DTC, both alone and in combination with other agents, may be indicated.

Imuthiol influences on cytotoxic T cells and NK activity in +/+ and athymic nude BALB/c mice

The effects of imuthiol (sodium ditiocarb, DTC) on the expression of cytotoxic responses (CTL) and natural killer (NK) activity were evaluated in aged and young euthymic mice, and in nu/nu BALB/c mice. Imuthiol generated CTL and concomitantly reduced NK activity in nu/nu mice, suggesting that the agent can generate T cells in athymic nude animals. Treatment for up to 4 months augmented spleen NK and CTL activities in young or aged euthymic mice, but the generation of CTL in old animals was increased by long-term treatments better than by a single injection. The capacity of imuthiol to activate specific and nonspecific cytotoxic functions in euthymic mice may contribute to enhancement of resistance in vivo against transformed cells after treatment with this agent.

Role of the transfer of metabolites from hepatocytes to splenocytes in the suppression of in vitro antibody response by dimethylnitrosamine

The metabolism and subsequent immunosuppressive effects of dimethylnitrosamine (DMN) were investigated in mixed cultures of mouse hepatocytes and mouse splenocytes. Hepatocytes were shown to activate DMN to an immunosuppressive form that caused the suppression of the in vitro antibody response to the T-dependent antigen, sheep erythrocytes (SRBC). A significant increase in the binding of DMN metabolites to trichloroacetic acid (TCA) precipitable material in splenocytes was induced when 94 microM [14C-methyl]DMN was added to the co-culture medium, indicating that reactive intermediates of DMN were transferred from hepatocytes to splenocytes and resulted in alkylation of macromolecules in splenocytes. The amount of [14C]DMN bound to TCA precipitable material in splenocytes increased in a time-dependent manner up to 4 hr of incubation. Aminoacetonitrile (AAN), a high-affinity DMN demethylase inhibitor, reversed the suppression by low concentrations of DMN (0.5 to 5 mM), but not by high concentrations of DMN (greater than 5 mM). AAN also inhibited the binding of [14C]DMN to both hepatocytes and splenocytes. These results suggest that reactive metabolites of DMN are released from hepatocytes and that the suppression of the antibody response by DMN is mediated via these reactive intermediates.

The nature of tumor presentation in the animal changes the effects of levamisole treatment on metastasis

We have investigated the ability of levamisole (LMS) to modulate growth and metastasis of a rat hepatocarcinoma. LMS treatment decreased spontaneous metastasis to the lungs and lymph nodes, while it increased tumor lung colonization following intravenous tumor cell inoculation. Both serum immunoglobulin (Ig) and circulating immune complex (CIC) levels were higher than normal in tumor-bearing rats. LMS treatment did not alter these parameters in the lung colony assay, while a small decrease of serum IgG was noted for LMS treated animals in the spontaneous metastasis assay. We found no convincing evidence for CIC levels, immunoglobulin isotype shifts or induced changes in natural killer (NK) cell reactivity being involved in the observed LMS modulation of tumor metastasis. The nature of the presentation of the tumor in the animal, however, appeared to be critical in determining the metastatic response to LMS therapy.

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.

Effects of levamisole on primary cultures of adult rat hepatocytes

Levamisole represents one of several new compounds that exhibit immunomodulating activity. Pharmacological data have documented a relationship between liver drug metabolism of levamisole and its subsequent immunomodulating activity. To directly investigate this relationship in a controlled manner, primary cultures of adult rat hepatocytes were treated with levamisole, and ultrastructural and biochemical effects were analyzed. Ultrastructurally, levamisole did not disrupt the cellular architecture of the hepatocytes. Biochemically, levamisole stimulated alkaline phosphatase activity and elevated microsomal cytochrome P-450 content after a 48-hr incubation. High pressure liquid chromatographic analysis of levamisole metabolites produced by cultured hepatocytes suggested the formation of a hepatocyte-specific metabolite(s) that may be associated with its immunological mode of action.

Early changes in immune parameters induced by an acute nonantigenic inflammation in mouse: influence of imuthiol

Calcium pyrophosphate (CaPP)-induced pleurisy, may represent one of the simplest expressions of inflammation in that the irritant is a non-diffusible, non-antigenic and non-pyrogenic agent. Spleen or lymph node T or B cell numbers and activities, as well as NK activity, were modified at distance by CaPP-pleurisy. An intense increase in blood polymorphonuclear cells was also triggered by the inflammatory process. Treatment with imuthiol (sodium diethyldithiocarbamate), an agent known to be active on the T-cell lineage, restored towards control values the inflammatory response and tended to normalize white blood cell percentages altered by the inflammatory process. The findings suggest imuthiol could be employed as a virtually nontoxic and non-steroidal anti-inflammatory agent.

Favorable influences of imuthiol on mouse reproduction and immune system of offspring

A physiological immature immune system in newborns is a common feature frequently associated with increased susceptibility to infections. The properties of imuthiol (purified sodium diethyldithiocarbamate), an agent specifically active on the T-cell lineage, and virtually devoid of toxicity for man or animals, encouraged us to determine whether imuthiol administered to the dams could increase the immune capability of offspring without altering fecundability and birth rate. Experiments performed either in histocompatible or histoincompatible mating systems, show that chronic administration of imuthiol prior to mating and/or during pregnancy stimulated newborn mice to increased T-cell-dependent responses, without altering birth rates and growth curves in progenies. The data suggest that imuthiol has no teratogenicity or deleterious influences on mouse gametes, and might be useful to prevent immunodepression-associated infections in newborns.

Restoration of defective EAG-rosetting capacity of cancer patient neutrophils by levamisole

Levamisole, used in vitro at therapeutic concentrations, was found able to restore the defective Fc-receptor activity of cancer patient neutrophils. In addition, the drug prevented the inhibition of normal neutrophils Fc-receptor function by cancer patient sera. The neutrophil Fc-receptor function was also restored in six of seven cancer patients after in vivo administration of levamisole (2.5 mg/Kg/day for 3 days). Due to the central role played by the Fc-receptor function in host defence mechanisms, including phagocytosis as well as antibody dependent cellular cytotoxicity, the capacity of levamisole to restore defective neutrophil Fc-receptor function in cancer patients could contribute to the "immunomodulating" effect of the drug.

In vivo radioprotective activities of diethyldithiocarbamate (DDC)

Studies were performed to determine whether diethyldithiocarbamate (DDC) protects against radiation damage to bone marrow, jejunal crypts, testicular tubules, hair follicles, tissues in the leg responsible for leg contractures, and a fibrosarcoma (FSA) of C3Hf/Kam mice. In most experiments, DDC at a dose of 400 mg/kg or 1000 mg/kg body weight was given i.p. 30 minutes before single doses of gamma radiation. DDC (1000 mg/kg) given 30 minutes before whole-body irradiation protected hematopoietic stem cells by a factor (PF) of 1.59, as assessed by the LD50/30 assay, and by PFs of 1.32-1.55, as assessed by the endogenous spleen colony assay. A dose of 400 mg/kg DDC was less effective. Protection was also significant against hair loss and leg contractures; PFs produced by 1000 mg/kg DDC were 1.44 and 1.38-1.51, respectively. Jejunum was protected by 400 mg/kg DDC (PF = 1.2), but not by 1000 mg/kg. The opposite was observed with testis: 1000 mg/kg was protective (PF = 1.2), but not 400 mg/kg. DDC also protected the FSa tumor, either as lung micrometastases or as a solitary tumor in the leg. Both 400 mg/kg and 1000 mg/kg DDC protected 4 day-old micrometastases by a PF of approximately 1.1. DDC at a dose of 1000 mg/kg protected 8 mm leg tumors by a PF of 1.24 at the TCD50 level. Therefore, DDC protected both normal tissues and FSA, but the degree of protection varied greatly. A therapeutic gain was achieved in some instances.

Immune capability of rats with colorectal carcinoma treated by resection with or without 5-fluorouracil or levamisole

The immune status of rats with chemically induced colorectal tumors was investigated for 8 weeks following treatment by resection, resection plus 5-fluorouracil (5-FU), and resection plus levamisole. Normal rats without tumors were given identical treatment and acted as controls. Tumor rats regained their ability to respond to an allograft of allogeneic lymphocytes after surgical excision of the tumor for a short period. Adjuvant Levamisole treatment enhanced this responsiveness, but adjuvant 5-FU depressed it. The spleen and lymph node cells of tumor-bearing rats showed greater spontaneous and PHA-induced cytotoxicity for chicken red blood cells than control rats (P less than 0.001), and adjuvant therapy did not alter this response. However in control animals, levamisole treatment did augment the antibody-dependent cytotoxicity of their spleen and lymph node cells. Rats receiving tumor resection alone were immune by leukocyte migration inhibition at 8 weeks only, while those receiving either adjuvant exhibited an immune response to the same homogenate for 4 and 8 weeks.

Involvement of brain neocortex and liver in the regulation of T cells: the mode of action of sodium diethyldithiocarbamate (imuthiol)

Sodium diethyldithiocarbamate ( imuthiol ), a non-antigenic and non-carcinogenic compound, devoid of toxic effects at immunostimulant doses, shows distinctive properties in recruitment and activation of T cells. Studies on its mode of action disclosed unsuspected links between the immune system, the endocrine liver and the central nervous system. Evidence was obtained indicating that the brain neocortex modulates T-cell mediated events, most likely via control of specific hormonal synthesis by the liver. The influence of imuthiol is determined at the level of the brain neocortex.

Immunostimulation. Clinical and experimental perspectives

Three classes of immunostimulating drugs are described, each representing a different approach to the problem of pharmacological immunostimulation. The rationale for the use of microbes or microbial agents as immunostimulators rests on the fact that some micro-organisms, especially those that replicate intracellularly, carry a special potential to activate macrophages. Clinically, the use of these agents in patients with tumors and infections has been disappointing; however, there have been positive exceptions like the responsiveness of melanomas and bladder carcinomas to the injection of BCG. Many of the inconclusive results may be due to insecurities in the dosage of microbial preparations and to a general lack in standardization. Some structures with high efficacy and low toxicity which have recently evolved from this field deserve further investigation. A number of structurally unrelated synthetic compounds was found to influence immune parameters. Levamisole can today be classified as an immunostimulating drug with limited utility in recurring infections and in chronic polyarthritis. Several immunostimulating drugs which have attracted interest contain a purine as the effective component. This is not surprising in view of the fact that many genetically determined immunodeficiencies can be traced to defects of enzymes which play a crucial role in purine biosynthesis. Finally, the potential role of lymphokines as stimulators of the immunosystem is briefly described. Some of these glycoproteins have recently become available for clinical trials. Others will be made available through genetic engineering. The therapeutic utility of these compounds is not yet clear; they will, however, be of great value as probes for the study of immune functions and for the development of immunopharmacology.

Enhancement of colloidal clearance in normal rats by sodium diethyl dithiocarbamate (DTC)

Enhancement of colloidal clearance in normal rats is induced by sodium diethyldithiocarbamate, administered by the oral route. Enhancement is only observed after a lag period of greater than seven days. The study evidences the efficacy of oral administration of DTC and a weekly frequency of dosing in this clearance model.

Effect of levamisole on cytotoxic T-cell-mediated immune resistance to L1210 murine leukemia in hyperimmune mice

The effect of levamisole (LMS) on T-cell-mediated antitumor immunity was examined in adult and aged mice hyperimmune to L1210 leukemia. The immune resistance of aged mice was depressed compared with that of adult mice, which almost completely rejected 5 X 10(7) L1210 cells inoculated IP. A significant level of tumor-specific cytotoxicity was detected in the spleen cells of adult hyperimmune mice by the 51Cr-release assay after in vitro sensitization with mitomycin C-treated L1210 cells. This was mediated by cytotoxic T cells, since in vivo administration of antithymocyte serum or in vitro treatment of the spleen cells with anti-Thy 1.2 antibody and complement abrogated the cytotoxicity completely. In aged mice, however, cytotoxic T-cell activity was lower although the animals were immune to L1210. Administration of LMS (0.38 mg/kg) restored the depressed cytotoxicity of aged mice to the level seen in adult mice. Furthermore, in adult hyperimmune mice LMS augmented T-cell-mediated cytotoxic activity and restored the reduced cytotoxicity caused by in vivo administration of antithymocyte serum. These results indicate that LMS was effective in augmenting T-cell-mediated tumor immunity in immunologically competent or deficient hosts.

The production of T-cell-inducing factors in mice is controlled by the brain neocortex

The synthesis of factors that monitor the expression of the Thy-1 cell surface component by marker-negative precursor cells requires an intact left cerebral cortex, whereas the activity of sodium diethyldithiocarbamate, an immunopotentiator that increases this synthesis, seems to require an intact right neocortex. These results suggest a role for the cerebral cortex in the coordinated interregulation of lymphocyte subclasses. The finding extends previous information suggesting relationships between the central nervous system and the T-cell arm of the immune system.

Sodium diethyldithiocarbamate (imuthiol) and cancer

Sodium diethyldithiocarbamate (imuthiol), a nonantigenic, nontoxic and noncarcinogenic compound, evinces distinctive properties in recruitment and activation of T cells, and no direct influences on B cells or macrophages. The biological attributes of imuthiol (destruction of neoplastic cells, bacteria, fungi and parasites; a detoxifying influence against carcinogens or agents toxic for the liver) could strengthen its activity as a biological response modifier. Preliminary clinic testings show that imuthiol restores T cell activities and regulates the ratio among T cell subsets in cancer patients, without untoward side effects.

Specific unresponsiveness to sheep red blood cells visualized by levamisole in athymic nude mice

The administration of levamisole at the time of and 2 days after challenge with 10(8) SRBC significantly increased the direct anti-SRBC PFC response of nude mice. Pretreatment of nude mice of BALB/c and C 57 B1/10Sn strains with 10(9) or 10(8) SRBC injected 14 and 7 days before challenge suppressed the increase of the immune response. Pretreatment with 10(7) SRBC did not induce this inhibition. Administration of levamisole at the time of pretreatment with SRBC did not prevent the induction of inhibition. It is suggested that B cell exhaustion is the cause of the observed unresponsiveness.

Effects of levamisole on human natural killer and killer cell activity and production of interferons

The effect of levamisole on natural killer (NK) and killer (K) cell activities and on interferon production was determined in both normal subjects and cancer patients. Levamisole had no effect on these cytolytic immune effector cells in vitro. It did not induce interferon production. Sequential determinations of NK cell activity and interferon plasma levels after single oral doses of levamisole failed to demonstrate an effect of levamisole on spontaneous cytotoxicity or interferon production.

Induction of E-rosette-promoting factor in human plasma by levamisole: an assessment in a patient with partial DiGeorge syndrome

A male infant with partial DiGeorge syndrome responded to weekly administration of levamisole (2.5 mg/kg of body weight) with an increase of circulating E-rosette-forming T cells. Thymic hormone activity in plasma appeared to be elevated to a near-normal level of 11.6 ng thymopoietin equivalent/ml after levamisole administration. The in vitro incubation studies indicated that levamisole by itself had no E-rosette-promoting ability, but a dialysable and relatively heat-stable plasma factor induced by levamisole both in the patient and in healthy individuals had E-rosette-promoting activity for the patient's lymphocytes. Such a plasma factor, however, could not be induced in all four thymectomized myasthenic subjects examined, suggesting a thymus-dependent nature of the plasma factor. These results suggest that levamisole might mediate an increased secretion of humoral factor(s) with E-rosette-promoting activity, even from such a rudimentary thymus as in the partial DiGeorge syndrome.

In vivo enhancement of mitogen-induced lymphocyte DNA synthesis by sodium diethyl-dithiocarbamate (DTC)

Sodium diethyl dithiocarbamate (DTC), a low molecular weight sulphur compound, has been previously shown to be endowed of immunomodulatory properties. To get a better understanding of the mechanisms whereby DTC regulates the immune response, mitogen-induced lymphoproliferation was studied in spleen from guinea pigs treated with a single i.v. injection of DTC. The results clearly show that DTC enhances, after a lag period, DNA synthesis in T and B lymphocytes. DTC which appears not to act at the level of immuno-competent cells seems to modulate the immune responses through indirect pathways.