Inhibition or enhancement of rat mammary tumors dependent on dose BCG

Theoretical considerations for thresholds in chemical carcinogenesis

There is increasing evidence for non-linear relationships for gene mutations, chromosomal aberrations and even tumor incidences in response to low doses of genotoxic carcinogens. To attain the biological relevance of such non-linear responses, there is a need to identify the underlying defense mechanisms that allow tolerance to low doses of genotoxicants. This communication discusses presumptive cancer prevention mechanisms that may contribute to thresholds, i.e. points of departure, for each endpoint, from initial DNA lesion to tumor formation. We discuss a sequential order of genome protection during carcinogenesis where genotoxicant scavenging, cellular efflux, DNA repair, elimination of damaged cells by apoptosis, autophagy, silencing by DNA damage-triggered replicative senescence, and finally, elimination of transformed (premalignant) cells by the immune system are thought to be responsible for a threshold in tumor formation. We highlight DNA repair, for which experimental evidence has been recently provided to dictate a role in PoDs. In conclusion, from a theoretical perspective it is reasonable to posit that tolerance to low dose levels exists for each requisite step of tumor formation and these tolerance mechanisms are critical in determining thresholds in chemical carcinogenesis.

Dermatologic tumors (excluding sarcoids)

Cutaneous neoplasia represents a clinical problem with which veterinarians are commonly challenged. This article addresses equine cutaneous squamous cell carcinoma, squamous cell papilloma, melanoma, mastocytosis, and lymphosarcoma. Current concepts regarding the origin, pathogenesis, diagnosis and treatment of each neoplasm is emphasized.

In vivo augmentation of local xenogeneic graft-versus-host reaction by cimetidine and Bacillus Calmette-Guerin

Histamine-2 receptor blocker therapy (cimetidine) was combined with nonspecific Bacillus Calmette-Guerin (BCG) immunomoderation in order to obtain a more directed immunostimulatory response. To establish this the local xenogeneic graft-versus-host reaction (XGVHR) was used as objective in vivo parameter. In this placebo-controlled experiment the lymphocytes of inbred Sprague-Dawley rats were transferred intradermally to partially immunosuppressed guinea pigs after treatment with either or both of the test substances. The surface areas of the local XGVHRs were evaluated 48 and 72 h later. The local XGVHRs caused by lymphocytes obtained from rats treated with either cimetidine or BCG alone did not differ significantly from those caused by lymphocytes obtained from placebo-treated rats. Combination therapy, however, resulted in significant augmentation of the local XGVHR, clearly indicating a synergistic effect between cimetidine and BCG. The XGVHR appears to be a satisfactory model for evaluating drug effect on cell-mediated immune reaction in vivo.

Effects of radiolabelled monoclonal antibody infusion on blood leukocytes in cancer patients

This study was undertaken to investigate the effects of a single infusion of radiolabelled murine monoclonal antibody (MAb) on peripheral blood leukocytes in cancer patients. Eleven patients with disseminated colon cancer, malignant melanoma, or lung adenocarcinoma were infused with 111In-labelled anti-ZCE 025, anti-p97 type 96.5c, or LA 20207 MAb, respectively. Blood samples were obtained before infusion, immediately after infusion (1 hr), and at 4 and 7 days postinfusion. Flow cytometry analysis of CD3+, CD4+, CD8+, CD16+, and CD19+ lymphocytes showed increasing CD4:CD8 ratios in seven patients after infusion. This phenomenon was not restricted to antibody subclass or to type of cancer. Two of the remaining patients exhibited a marked post-infusion increase in CD8+ cells. In all three patients with malignant melanoma, decreasing levels of CD16+ lymphocytes were noted after infusion and natural killer cell cytotoxicity showed fluctuations which paralleled the changes in the CD16+ subpopulation. Oxygen radical production by phagocytic cells was markedly affected in three subjects. These results suggest that a single infusion of radiolabelled murine MAb may alter the balance of critical lymphocyte subpopulations and modulate other leukocyte responses in cancer patients.

Host-mediated antiviral activity of Lactobacillus casei against cytomegalovirus infection in mice

The protective effect of heat-killed Lactobacillus casei (LC) against murine cytomegalovirus (MCMV) infection was examined. ICR mice treated once with LC 1 day or 2 days before challenge survived lethal infection, but untreated or Lactobacillus fermentum (LF)-treated mice did not. The protective effect was evidenced by an increase in plaque-forming units (PFU) per 50% lethal dose (LD50) and a decrease in titers of infectious viruses replicated in the target organs. This was further confirmed by severity of histopathological damage to the target organs, especially the liver. LC neither inactivated MCMV nor inhibited its replication in mouse embryonic fibroblasts (MEF). The spleen cells from LC-treated mice inhibited its replication in MEF on co-cultivation. Augmentation by LC of splenic natural killer (NK) cell activity correlated with survival of mice from otherwise lethal MCMV infection. Cytotoxic activity of peritoneal cells and level of serum interferon (IFN) were elevated after MCMV infection, but they were not associated with survival of mice nor with treatment of LC. The protective effect of LC was not clear in NK-deficient beige mutant (bgJ/bgJ) mice, when compared with that in their littermate (bgJ/+) mice. Poor protection of bgJ/bgJ mice by LC treatment correlated with failure to induce NK cell activity by LC treatment in the mutant mice. Thus, it is likely that LC protects mice from MCMV infection by augmentation of NK cell activity.

Effect of cyclophosphamide and levan treatment on bone marrow and peripheral blood cells in B16-F10 melanoma-bearing mice

Immunotherapeutic agents have often been found to provoke opposite effects on tumor growth--inhibitory or stimulatory--depending on dose, timing or route of administration. The reason for these opposite effects is not yet known. Levan (polyfructose), an immunomodulatory polysaccharide, has been found to exert opposite effects on the growth of the F10 variant of B16 melanoma. Low doses inhibit and high doses enhance the growth of this tumor. Cyclophosphamide (CY) augments the inhibitory effect of the polysaccharide. In order to elucidate the mechanism of these opposite effects, we tried to determine the changes induced by levan at inhibitory and stimulatory doses, alone or in conjunction with CY, on the lymphatic and hematopoietic systems of B16-F10 melanoma-bearing mice. In a previous study we reported the effect of these treatments on the morphology of spleen and lymph nodes (Leibovici, Kopel, Siegal & Gal-Mor (1986). Int. J. Immunopharmac., 8, 391). In the present study, we examined the effect of the treatments on bone marrow and peripheral blood composition. The growth of the tumor itself, as well as the various treatments, induced very marked changes in both bone marrow and blood. Tumor inoculation produced a sharp leukopenia and anemia followed by a restoration of both white and red blood cells. In the bone marrow, the tumor caused a gradual decrease in lymphocyte number. CY accentuated the severe leukopenia caused by the tumor. Lymphocyte depletion was prolonged, while restoration of granulocytes was achieved by day 7. A similar pattern of changes was observed in the bone marrow. With levan, opposite effects were observed in blood and bone marrow with the two doses in relation to the number of the cells of the lymphoid and myeloid lines: while 0.1 mg (tumor inhibitory) doses caused a more active restoration of lymphocytes as compared to 10 mg (tumor stimulatory) doses, an opposite effect was seen on the myeloid series--the high dose induced a more pronounced granulocytosis than the low dose. In the combined treatment, the low levan dose accelerated lymphocyte restoration in bone marrow compared to CY, while the high dose delayed the recovery of these cells. The results of the present study in conjunction with our previous study may explain the basis of the intriguing tumor inhibitory-stimulatory effects of some immunomodulators. Moderate increases in myeloid cell series appear to favor tumor inhibition and high increases favor tumor stimulation. In addition, the results of this study suggest that a regulatory relation might exist between the proliferation of the lymphoid and myeloid cell series.

Antitumor activity of Lactobacillus casei (LC 9018) against experimental mouse bladder tumor (MBT-2)

The purpose of this paper is to investigate the inhibitory effect of Lactobacillus casei (LC 9018) on the growth of transplantable murine bladder tumor. Lactobacillus casei, viable and/or heat-killed bacteria, either in oral or intravenous administration, produced a significant inhibitory effect on the tumor growth and much less pulmonary metastasis.

Immunogenicity of viable tumor cells. A comparison of xenogenized tumor cells and BCG-tumor cell mixtures

The immunogenicity of KMT-17 fibrosarcoma cells which had been xenogenized by infection with FV was compared to that of KMT-17 cells which had been admixed with BCG. We report here that 10(5) and 10(6) KMT-17 cells also grew progressively to kill rats, but when 10(5) KMT-17 cells were administered with BCG the tumor cells did not grow in the majority of rats. The strength of immunogenicity (ETD50), as measured by the number of immunizing cells required for a suppression of growth of 10(7) KMT-17 cells in 50% of the rats, was 2.1 X 10(3) for FV-KMT-17 and 36.3 X 10(3) for BCG + KMT-17. The tumor cell dose (LTD50) which was required to kill 50% of the rats immunized with 10(5) FV-KMT-17 was more than 10,000 times higher than that found in normal rats, whereas the number of tumor cells required to kill 50% of the rats immunized with the same number of BCG + KMT-17 was only 3,680 times higher than the amount found in normal rats. Thus the immunogenicity of FV-KMT-17 is much stronger than that of BCG + KMT-17. The difference in immunogenicity between the two vaccines was also observed in the tumor-neutralizing activities of spleen cells obtained from rats which had been immunized with both vaccines, as measured by a Winn assay. Moreover, the antitumor activity of spleen cells from rats immunized with FV-KMT-17 was concentrated in the carrageenan-resistant and plastic nonadherent cells, while that of spleen cells from rats immunized with BCG + KMT-17 was observed in carrageenan-sensitive and plastic adherent cells as well as in nonadherent cells. The involvement of different effector cells indicates that different mechanisms operate in the antitumor resistance in rats immunized with either FV-KMT-17 or BCG + KMT-17.

Anti-tumour effect of humoral and cellular immunities mediated by a bacterial immunopotentiator, Lactobacillus casei, in mice

Administration of a mixture containing Lactobacillus casei YIT 9018 (LC9018) and methylcholanthrene-induced fibrosarcoma (Meth A) cells into the peritoneum of syngeneic BALB/c mice suppressed the tumour growth and protected the mice from tumour death. With the appearance of the anti-tumour activity, serum complement-dependent tumour cytotoxic (CDC) antibody was induced on the 5th day after the administration as a result of the adjuvant effect. The cytotoxic antibody was not found in serum on the 5th day after inoculation of Meth A cells alone, but it was induced before the mice died of the tumours. Adjuvant induction of the cytotoxic serum antibody at an early time was also observed using Kirsten murine sarcoma virus-transformed tumour (K234) cells. Both of these cytotoxic antibodies in sera from Meth A-suppressed and the tumour-bearing mice were specific for the tumour cells and were IgM class, since they were absorbed with rabbit anti-mouse IgM antibody. However, the cytotoxic antibody was not found in the peritoneal cavity which was the tumour inoculation site, but binding antibody against the tumour cells was faintly detected in the region using an enzyme-linked immunoabsorbent assay (ELISA). In neutralization tests, the cytotoxic antibody did not exert anti-tumour activity in recipient mice when it was administered to the mice along with the tumour cells or when it was administered i.v. at the time of tumour inoculation. Moreover, the cytotoxic antibody was not available for the antibody-dependent cell-mediated cytotoxicity (ADCC). These results suggest that the cytotoxic antibody did not exert anti-tumour activity in the tumour-suppressed mice. In contrast, peritoneal exudate cells (PEC) on the 5th day, and PEC and spleen cells on the 15th day after i.p. administration of the mixture exerted strong anti-tumour activity as measured by the Winn test. In conclusion, the adjuvant effect of LC9018 induced tumour-specific humoral and cellular immunities but the anti-tumour activity was dependent only on the cellular effectors of the host. The possible use of LC9018 in tumour immunotherapy is discussed.

Comparison of antitumor activity of Lactobacillus casei with other bacterial immunopotentiators

Antitumor activity of Lactobacillus casei YIT 9018 (LC9018) was demonstrated by intralesional (i.l.) or intravenous (i.v.) administration into tumor-bearing mice which were inoculated with methylcholanthrene-induced fibrosarcoma (Meth A) or Kirsten murine sarcoma virus-transformed tumor (K234) cells. Its activity was significantly superior to the activity of two other species of lactobacilli but was nearly the same as that of Corynebacterium parvum or Mycobacterium bovis Bacille Calmette-Guérin (BCG). I.l. or i.v. administration of LC9018 into the tumor bearers caused local transient swelling or hepatosplenomegaly but did not cause other pronounced lesions. There was no significant difference in the degree of hepatosplenomegaly in LC9018 and that in other immunopotentiators. In mice whose tumors had regressed as a result of administration of LC9018 or the other immunopotentiators, the phytohemagglutinin P (PHA-P) response of the spleen cells was less than that of mice whose tumors progressed, and approached the normal level. The PHA-P response of popliteal lymph node cells proximal to the tumor lesion was fairly low compared with the splenic PHA-P response and there was no difference between the lymphocytes from mice whose tumors had regressed or progressed. Adjuvant activity of LC9018 in inducing tumor immunity was demonstrated by administering a mixture of LC9018 and Meth A cells to mice. This adjuvant activity was of the same efficiency as that of C. parvum and BCG. The presence of the antitumor activity of LC9018 in cell wall components was deduced from fact that removal of its cell wall by endo-N-acetylmuramidase (M-1 enzyme) abolished the activity. The possible availability of LC9018 for immunotherapy of tumors is discussed.

The influence of dietary fat and non-specific immunotherapy on carcinogen-induced rat mammary adenocarcinoma

The incidence of mammary adenocarcinoma in Sprague-Dawley female rats, caused by the carcinogen 7,12-dimethylbenz(alpha)anthracene, was influenced by the level of dietary fat fed after exposure to carcinogen. Carcinogen was given by stomach tube to 50-day-old rats, and tumors were evaluated when rats were 9 months old. Rats on diets containing 20% unsaturated fat had a tumor incidence of 97%, while rats changed to a low-fat diet (2% unsaturated fat) three or four weeks after exposure to the carcinogen had an incidence of 45%. Some rats on each diet were given two treatments with the methanol extraction residue of Bacillus Calmette-Guerin, either three and five weeks after carcinogen or four and six weeks after carcinogen. Tumor incidence in the treated group and the untreated group was the same when rats were maintained on the high-fat diet, but tumors in the treated group were larger and the disease was more severe by histological criteria. These tumors were more anaplastic and many were extensively infiltrated with lymphocytes compared to the untreated group. Tumor incidence was significantly lower in rats changed to the low-fat diet (45%) than in those on the high-fat diet (97%), and tumor incidence was reduced to 20% when rats changed to the low-fat diet were treated with methanol extraction residue. The treated group had less severe disease than the untreated group on the low-fat diet. Only half the tumor-bearing rats in this group had malignant tumors, and none were invasive. Methanol extraction residue protected most rats on the low-fat diet against mammary adenocarcinoma, and reduced the severity of disease in those rats that did develop tumors. Methanol extraction residue treatment provided no protection, and even increased the severity of disease, in rats on the high-fat diet.

Enhancement of metastasis development by BCG immunotherapy

When BALB/c mice bearing growing transplants of a syngeneic colon carcinoma--Colon Tumor 26 (CT 26)--were treated with Bacillus Calmette-Guerin (BCG), no effect on tumor growth rate or survival time was observed compared to untreated controls. However, after excision of primary tumor transplants, enhanced development of lung metastases was noted in the BCG-treated mice, resulting in both as increased mortality rate (from metastatic disease) and a shorter survival time.

Active, specific immunotherapy of murine leukemia. II. Adjuvant effect of Corynebacterium parvum

We have previously shown that irradiated LSTRA cells (LX) were immunogenic and could prolong survival of mice bearing LSTRA tumors. This study demonstrated that addition of Corynebacterium parvum to the LX dramatically improved the strength of tumor immunity. In pretreatment-challenge experiments, C. parvum augmented the immunogenicity of 10(6) LX given intradermally, with an optimum dose of 0.14-1.4 microgram C. parvum per mouse. In therapy experiments (intraperitoneal vaccine treatment after tumor cell challenge), the therapeutic effect of 10(7) LX was improved by admixture of C. parvum, leading to a larger number of cured mice, permitting treatment of a larger challenge inoculum, and allowing later initiation of treatment than was possible with LX alone. Optimal dose of C. parvum for therapy was 1,400 microgram per mouse. Presensitization to C. parvum or use of repeated vaccine injections did not further improve the therapeutic effect. Cure of tumor-bearing mice by the mixed vaccine was tumor-specific. These results suggest that C. parvum is a potent adjuvant for use in active, tumor-specific immunotherapy.