Evidence for splenic suppressor cells in C3H/He, T-cell-deprived C3H/He, and nude mice bearing a 3-methylcholanthrene-induced fibrosarcoma.

Suppressor cells were demonstrated in the spleens of C3H/He mice carrying 3-methylcholantrene-induced fibrosarcomas. These cells inhibited the in vitro reactivity of normal lymphocytes to T- and B-cell mitogens. They disappeared within a few days after the tumor was surgically removed. Pretreatment of spleen cells (ScC) from tumor-bearing (TB) mice with either iron and a nagnet, antiserum against Thy 1.2 antigen plus complement, or antiserum against immunoglobulin plus complement demonstrated that the suppressor cells were adherent, non-T-cells bearing immunoglobulin at their surfaces. The suppressive effect could still be demonstrated by addition of SpC from TB mice 24 or 48 hours after phytohemagglutinin stimulation of normal SpC, SpC from TB C3H/He mice inhibited mitogen-induced stimulation of both C3H/He and DBA/2 lymphocytes. In T-cell-deprived TB C3H/He mice, suppressor cells were also observed and had the same characteristics as those in non-T-cell-deprived mice. In nude mice, however, although suppressor cells were active, they were not adherent and did not bear immunoglobulin at their surfaces. The existence of these suppressor cells may be one reason why the immune system of TB animals is unable to reject the tumor.     

Long-term cyclophosphamide treatments against primary mammary tumors in C3H/He mice

Tumor-free inbred female C3H/He mice were given weekly injections of cyclophosphamide to prevent or delay the expected occurrence of spontaneous mammary carcinomas. Chemotherapy was started at an age when the mice would already have developed preneoplastic hyperplastic alveolar nodules and tumors were likely to appear within a few weeks. Treatments were given for periods ranging from 10 to 50 weeks with various schedules and doses. The mice were observed for the development of tumors until they died or were killed. Tumors were excised as they appeared. Treatments were most effective in reduction of the number of primary tumors when started early and given continuously. Longer term, low-dose treatments gave better results than short-term, high-dose treatments, although the total dose given was the same. The prophylactic effect of the drug appeared to be by the destruction of occult, drug-sensitive tumors, rather than by delay of their appearance. The toxicity of moderate, continuous drug administration was well tolerated with no mortality and only minor transient weight loss.     

Studies of the Rat Immune Response to Plasmacytoma 5563 in C3H Mice

Washed lymphocytes from immunized rats showed no reaction against mouse plasmacytoma 5563 in vivo or in vitro.     

Combination heparin plus cortisone treatment of two transplanted tumors in C3H/He mice

C3H/He inbred mice bearing either C3H mouse mammary or RIF-1 tumors of 180-mm3 volume were treated with a combination of heparin (500 anticoagulation U/ml drinking water) plus cortisone (either 250 mg/kg/day tapering to 37 mg/kg/day or a constant dose of 75 mg/kg/day). Five types of heparin were tested in this study. RIF-1 tumors shrank to approximately half the volume at the start of therapy after only 3 days of treatment; mammary tumors took longer to respond, not reaching half the starting volume until after 11 days of treatment. In both tumors response was transient, the tumors eventually regrowing. However, response to combined heparin and cortisone therapy was in fact no different from the response to cortisone used alone. Also, cortisone treatment was extremely toxic to these animals and experiments had to be terminated after about 3 weeks of therapy.     

Immunological studies on mouse mammary tumors. I. Induction of resistance to tumor isograft in C3H/He mice

An isografted tumor MM2, originating from a spontaneous mammary tumor in a C3H/He/mouse, killed 4- to 5-week-old mice within 30 days through intraperitoneal injection of 2 × 10⁴ cells per mouse. It was shown that resistance to the isograft was induced by injection of 1.5 × 10⁵ or 2.0 × 10⁵ tumor cells sensitized with serum (5 μg antibody N) of rabbits immunized with the tumor. Four weeks after injection of the sensitized MM2 cells, 173 C3H/He mice were challenged intraperitoneally with fresh unsensitized MM2 in doses of 5 × 10⁵ to 1 × 10⁶ cells per mouse. Of these, 119 mice survived without any sign of tumor growth while all untreated mice died. The mean survival time for untreated mice was 18.1 days (± 1.7) when inoculated with 5 × 10⁵ cells and 16.2 days (± 1.8) when inoculated with 1 × 10⁶ cells. After the second challenge with the same number of fresh unsensitized cells, 117 out of 119 mice survived without any sign of tumor growth. All of 15 mice randomly selected from these resistant mice were tested for acceptance of skin grafts from normal C3H/He mice. The grafts showed no rejection even 150 days after the second graft. After hyperimmunization of these resistant mice, the serum of the spleen extract taken from the mice inhibited growth of tumors when the tumors were premixed in vitro and injected intraperitoneally into C3H/He mice.     

Morphological observations during developing concomitant immunity against a C3H/He mammary tumor

During the developing phase of concomitant immunity against primary s.c. implants of the mammary carcinoma MC2, responder cells identified as Lyt 1 and Lyt 2 T-cell subsets and B-cells showed little tendency to infiltrate among the cells of the implants and did not appear to have any direct cytotoxic effect. Macrophages were also not cytotoxic at this time, but they were closely associated with the formation of a fibrous cellular capsule, always found around tumors in arrested growth or in regression. After a period of growth, about 20% of the MC2 implants regressed spontaneously. Surgical disruption of the capsules formed around 5-week-old primary tumor implants did lead to more frequent regressions, showing that a capsule that could destroy a tumor slowly also shielded the tumor against highly activated and effective systemic rejection mechanisms. In mice less than fully immunized with 3-week-old primary implants, the accumulation of responder cells at a second implant was rapid, and the development of a capsule was accelerated. Only the macrophages had developed a tendency to infiltrate among the tumor cells. Implants in partially immune mice had a lower mitotic index than did implants in normal mice. Of the second implants, 30% did not reach palpable size, and 42% regressed after a period of growth. Only after at least 5 weeks of immunization did a rapid destruction of second implants become evident. The tumor-destructive process was associated with infiltration by activated macrophages and was completed in 3 to 6 days.     

Restoration of lipopolysaccharide-mediated cytotoxic macrophage induction in C3H/HeJ mice by interferon-gamma or a calcium ionophore

Proteose peptone-induced peritoneal exudate macrophages (PEM) from C3H/HeJ mice do not respond to lipopolysaccharide (LPS) in vitro in terms of activation for tumor cytotoxicity. This unresponsiveness of PEM was overcome by addition of culture supernatant of normal mouse spleen cells stimulated with insoluble concanavalin A. The supernatant component responsible for the restoration of PEM sensitivity to LPS was indicated to be interferon (IFN)-gamma, because pretreatment of the supernatant with anti-mouse IFN-gamma antiserum, but not with anti-IFN-(alpha + beta) antiserum, abolished the supernatant activity and because recombinant murine IFN-gamma (rIFN-gamma) could replace the supernatant effect. Not only the LPS activation of tumor cytotoxicity of PEM but also the sensitivity of PEM to the lethal toxicity of LPS was restored by rIFN-gamma. IFN-gamma action in restoring the LPS responsiveness of PEM was mimicked by a calcium ionophore, A23187, but not by phorbol 12-myristate 13-acetate. These results suggest that IFN-gamma can restore LPS responsiveness of PEM from C3H/HeJ mice and that elevation of the intracellular calcium level is involved in the action of IFN-gamma.     

Preventive effect of the soluble tumor-associated antigens on DMBA induced tumorigenesis in C3H/He mice

In our previous studies, we showed that soluble tumor-associated antigens (sTAA) of 66 kDa and 51 kDa have distinct tumor-preventive effects on chemically induced mammary cancer in rats and are able to repair the damage caused by tumorigenesis in its early stages. In the present study, we investigated whether these proteins can prevent the development of chemically induced tumors in mice. The study was performed on C3H/He mice which have the ability to develop many spontaneous tumors with age. Forty-four, 6-week-old mice were exposed twice at a 2-week interval to the carcinogen 9,10-dimethyl-1,2-benz(alpha)anthracene (DMBA), at a dose of 2 mg/mouse administered intragastrically. Two months later, the mice were divided into two groups. One group received sterile saline twice a week at a dose of 0.2 ml/mouse, intraperitoneally (i.p.). The other group received sTAA twice a week at a dose of about 10 microl in 0.2 ml of sterile saline/mouse, i.p. Periodically, all mice were checked for the presence of tumors. The experiment was terminated at week 35. Vaccination with sTAA increased the time of involvement of mice in the experiment, prevented the tumorigenic effect of DMBA, and inhibited further development of existing tumors.     

Regulation of immune responses in SJL and F1 hybrid mice by gamma-irradiated syngeneic lymphoma cells

Syngeneic mixed lymphocyte-stimulating la+ lymphomas of SJL mice [reticulum cell sarcoma(s) (RCS)] were found to modulate immune responses in vivo. Simultaneous injection of 2 X 10(7) gamma-irradiated or glutaraldehyde-fixed RCS cells with the antigen sheep red blood cells (SRBC) or 2,4,6-trinitrophenol (TNP)-Ficoll markedly suppressed the subsequent plaque-forming cell response in the spleen. The suppression of the anti-SRBC response was prevented by pretreatment of the mice with cyclophosphamide, whereas the suppression of the anti-TNP-Ficoll response was not affected. RCS injection induced high interferon serum titers within 24 hours after injection, which were not prevented by pretreatment with cyclophosphamide. Injection of gamma-irradiated RCS cells (gamma-RCS) or RCS cell extract 2 days prior to antigen enhanced the anti-SRBC but markedly suppressed the anti- TNP-Ficoll response. Injection of RCS both on day -2 and day 0 enhanced the anti-SRBC response. SJL mice 8-9 months of age showed much less or no suppression when gamma-RCS cells were injected on day 0. Certain F1 hybrids of SJL also showed the gamma-RCS-induced suppression of the anti-SRBC response. Suppression was seen in SJL X BALB.B but not in SJL X BALB/c mice and in SJL X A.TH but not in SJL X A.TL mice, suggesting an I-region effect. F1 hybrids of SJL by B10 background mice showed no significant suppression. Enhancement of the anti-SRBC response by prior injection of gamma-RCS was seen in all F1 hybrid mice examined.     

Carcinogenicity of bucetin in (C57BL/6 X C3H)F1 mice

The carcinogenicity of bucetin [(3-hydroxy-p-butyrophenetidide) CAS: 1083-57-4], an antipyretic analgesic drug, was examined in 300 (C57BL/6 X C3H)F1 mice. Groups of 50 mice of each sex were treated with 1.5 or 0.75% bucetin in their basal diet for 76 weeks and then fed a basal diet for 8 weeks. Control groups were given a basal diet for 84 weeks. In 10 of 46 (22%) male mice given the high dose of bucetin and in 6 of 45 (13%) given the low dose, renal cell tumors were induced. Dysplastic lesions of the proximal tubules were frequently seen in the males given bucetin in a dose-related fashion. Neither tumorous nor preneoplastic lesions developed in the kidneys of bucetin-treated female mice and control animals. Papilloma of the urinary bladder in 1 male mouse and papillary or nodular hyperplasia in 9 mice of both sexes were observed in groups given the high dose of bucetin.     

Treatment of rhabdomyosarcoma in mice C3H/He by Co 60 and hyperbaric oxygen (author's transl)]

Experimental study of rhabdomyosarcoma with successive transplantation upon C3H/He mice, treated by irradiation (Co 60) and combined irradiation-hyperbaric oxygen (HBO), dating from 3, 14 and 15 days after transplantation. The data (tumor volume evolution, histological modifications, pulmonary metastases) are compared with controls. Conclusions: curative radiotherapy depends on starting treatment as soon as possible with or without HBO. After the 14th day, sensitisation to combined HBO and C60 is seen. The extension of pulmonary metastases is a function of tumor growth. Paradoxically metastases were less frequent after HBO only and more frequent after HBO-Co 60.     

Effect of dietary phenobarbital on spontaneous hepatic tumorigenesis in germfree C3H/He male mice

Phenobarbital (PB) is known to be a promoter of liver tumorigenesis in rats and mice. The present study was designed to examine the effect of PB on liver tumorigenesis in C3H/He germfree (Gf) male mice. Gf and conventional (Cv) animals were given an irradiated (5 Mrad) basal diet containing 200 ppm PB from 6 weeks old until termination of the experiment. When they were 12 months old, the animals were killed under CO2 inhalation and autopsied for the number and size of tumor nodules. The incidence of liver tumors was significantly higher in PB-fed Gf animals (67%) than in non-treated Gf controls (30%), and higher in PB-fed Cv animals (100%) than in non-treated Cv controls (75%). The number of tumor nodules per mouse was also significantly higher in PB-fed Gf animals (2.0) than in non-treated Gf controls (0.4), and higher in PB-fed Cv animals (4.5) than in non-treated controls (1.3). The present study demonstrated that dietary PB induced increases in number of the tumor nodules and decreases in the tumor size of C3H/He mice.     

Suppression of mammary tumorigenesis in C3H/He mice by ovariectomy or treatment with 2-bromo-alpha-ergocryptine: a comparison

We compared the effects of chronic treatment with 2-Br-alpha-ergocryptine (CB-154) and of ovariectomy on the genesis of mammary hyperplastic nodules (HN) and mammary tumors in the C3H/He mouse. CB-154 is an established potent suppressor of pituitary prolactin. Eighty-five 21- to 25-day-old female mice were divided into three groups. Group I received daily sc injections of 0.1 mg CB-154. Group II was ovariectomized and group III served as controls. Mice were examined weekly for mammary tumors. Fifteen months from onset of treatment all surviving mice were killed. The mean number of HN per inguinal mammary gland, total number of mammary tumors, and number (percent) of mice with mammary tumors in each group were, respectively: controls--4.6 +/- 1.1, 41, 24/29 (83%); ovariectomized--1.2 +/- 0.6, 20, 14/28 (50%); and CB-154-treated--0.2 +/- 0.1, 16, 13/28 (46%). A significant (P less than 0.001) and equally comparable inhibition of mammary tumor incidence was observed in the ovariectomized and CB-154-treated mice. Thus early ovariectomy and CB-154 treatment (specific inhibition of prolactin secretion) appeared equally effective in the prophylaxis of mammary tumorigenesis in the C3H/He female mouse.     

Presence of suppressor cells in spleens of mice bearing a weakly immunogenic syngeneic tumor.

Spleen cells of C57BL/6J mice bearing a poorly immunogenic syngeneic tumor T241 have been shown to suppress the mitogen-induced proliferative responses of normal spleen cells. However, no suppressive effect of these cells was observed on the generation of cytotoxic cells following immunization in vitro against H-2 histocompatibility antigens. The suppressor activity disappeared rapidly after the removal of the primary tumor. Spleen cells of tumor-bearing mice also suppressed the mitogen-induced stimulation of normal spleen cells of mice of different H-2 loci. Removal of phagocytic cells with carbonyl iron treatment had very little effect on the suppressor activity. Suppressor activity was enhanced following fractionation of cells through nylon wool columns. The suppressor population was found to resist anti-immunoglobulin serum and complement treatment, but treatment with anti-thymocyte serum and complement drastically reduced the suppressor activity. These results indicate that cells with suppressor activity have characteristics of T-lymphocytes.     

Carcinogenicity of o-ethoxybenzamide in (C57BL/6N X C3H/HeN)F1 mice

The carcinogenicity of o-ethoxybenzamide (CAS: 938-73-8), which is also called ethenzamide and which is widely used as an antipyretic anodyne in Japan, was examined in 298 (C57BL/6N X C3H/HeN)F1 mice. Groups of males and females were fed a diet containing 0 (control), 0.4, or 1.2% o-ethoxybenzamide for 96 weeks and sacrificed at the 100th week. Among the male mice fed the higher dose of the drug, the total incidence of liver cell tumors was 68%, with 18% of the mice developing hepatocellular carcinomas; both yields were significantly higher than those in the controls. In o-ethoxybenzamide-treated male mice the multiplicities of the hepatic cell tumors were also significantly higher than the multiplicity of the hepatic tumor in male control mice. A dose-response relationship with regard to both incidence and multiplicities of hepatic cell tumors in male mice was observed. In female mice fed o-ethoxybenzamide the incidence and multiplicities of the liver cell tumors were increased compared to those of the controls, but statistical significance was observed only in the multiplicity of tumors in mice given the lower dose. In both sexes hepatic cell tumors developed earlier than in the controls. These results show that o-ethoxybenzamide enhances the development of hepatic cell tumors in male (C57BL/6N X C3H/HeN)F1 mice.     

The lectin binding characteristics of spontaneous and phenobarbitone induced hepatic lesions in C3H/He mice

The surface membrane glycoprotein patterns of spontaneous hepaticnodules, pfaenobarbitone induced nodules and hepatocellularcarcinoma were studied in the C3H mouse using lectin histochemistry.The lectin binding patterns of hepatocellular carcinoma cellswere markedly different to those of non-tumour cells and similarto the pattern in chemically induced hepatocellular carcinomas.This supports the hypothesis that changes in surface glycoproteinare a consistent feature associated with malignancy. Similarchanges in the distribution of lectin binding sites were alsoseen in the phenobarbitone induced eosinophilic nodules andin a proportion of spontaneous basophuic nodules. Two populationsof early basophitic nodules were identified on the basis oftheir lectin binding patterns, and this may indicate a linkbetween one nodular type and carcinoma.     

脑瘤消胶囊对荷瘤小鼠免疫功能的影响

目的研究脑瘤消胶囊对荷瘤小鼠免疫功能的影响，探讨其抗肿瘤作用机制。方法脑瘤消胶囊灌胃给药后，测定小鼠腹腔巨噬细胞吞噬能力、脾指数和血清凝集素等。结果1．0～2．0g／kg剂量的脑瘤消胶囊可明显增加荷S180小鼠腹腔巨噬细胞吞噬百分率、吞噬指数和脾指数，并可提高其血清凝血素含量。结论脑瘤消胶囊可增强荷瘤小鼠免疫功能，其抗肿瘤作用机制与增强机体免疫功能有关。     

Kinetics of responses to tumor antigens and mouse mammary tumor virus in BALB/cCrgl and BALB/cfC3H mice

Spleen cells from BALB/cCrgl mice responded to murine mammary tumor virus (MuMTV) in cell-mediated immune assays at higher levels than did the spleen cells from the syngeneic BALB/cfC3H mice. Implantation in BALB/cCrgl with a chemically induced mammary tumor and in BALB/cfCrgl mice with spontaneous mammary tumors (SMT) arising in the same strain resulted in sensitization of these animals to the antigens of their tumors. Reactivities peaked 3 weeks after transplantation, whereas no positive reactions could be detected when tumors reached maximum size. A kinetic study with the use of MuMTV antigen(s) showed that the responses of lymphocytes from BALB/cfC3H with SMT followed the same pattern as that obtained with tumor antigens, which indicated that this might be a de novo sensitization. In sharp contrast, a steady type of response to MuMTV was observed with the spleen cells from BALB/cCrgl mice; i.e., the levels of responsiveness to MuMTV did not significantly vary at any stage of tumor development. In vivo studies explored the possible relevance of the in vitro cell-mediated immunity to the host defenses. MuMTV-expressing mammary tumor cells were implanted in BALB/cCrgl and BALB/cfC3H mice. The total incidence of tumors was significantly reduced and a delay occurred in their time of appearance in BALB/cCrgl mice in relation to BALB/cfC3H animals. Thus the in vitro reactivity to MuMTV antigen(s) in BALB/cCrgl mice was found to be coincidental with a degree of protection against the development of MuMTV-expressing mammary tumors.