The efficacy of BCG-induced tumor immunity in guinea pigs with regional and systemic malignancy

Summary It has been previously demonstrated that transplanted syngeneic line-10 hepatocarcinoma established in the skin of inbred guinea pigs (strain 2) regressed and regional lymph node metastases were eliminated after intratumoral injection of viable Mycobacterium bovis strain BCG. During the course of this reaction there is the development of systemic tumor immunity. The purpose of this study was to determine the relative efficacy of the induced tumor immunity to eliminate regional as well as systemic tumor burden. The approach to evaluate the efficacy of BCG-induced systemic tumor immunity in vivo, for regional as well as systemic tumor, was to develop a competition assay using increasing doses of intravascular disseminated line-10 tumor cells in animals with established regional tumors. The results clearly show that the efficacy of intratumoral BCG injection in producing regression of regional tumor is abrogated by initial intravascular doses of 10³–10⁶ line-10 cells. That the vascular systemic tumor burden diminished the effective systemic tumor immunity was demonstrated by the inability of animals with systemic tumor burdens to reject contralateral challenge of line-10 tumor cells. The capability of BCG-treated animals to reject contralateral line-10 challenge was inversely proportional to the initial intravascular tumor dose. Survival studies clearly demonstrate that a significant therapeutic effect could be achieved in guinea pigs with regional skin tumors and limited vascular metastases when the modality of therapy included BCG-intratumoral injection, followed 6 weeks later by surgery of the established skin tumor and regional lymph node. These results suggest that the development of tumor immunity after BCG-intratumoral injection is not impaired by the systemic tumor burden, but rather that it is preempted at distant sites. Abbreviations used in this paper: BCG, Bacillus Calmette-Guérin; i.a., intraarterially; i.d., intradermally; i.v., intravenously; SDA, superficial distal axillary.     

Lack of relationship of transplantation immunogenicity in C3H/He mammary carcinomas,with lymphoid hyperplasia and radiation-induced growth enhancement

Summary The therapeutic use of (a) radiation-inactivated tumor cells, (b) Bacillus Calmette-Guérin (BCG), and (c) heparinized plasma from normal mice to reduce radiation-induced impairment of existing antitumor resistance was investigated in female C3H/He hosts of syngeneic mammary carcinoma implants. The mice, which had been moderately presensitized 50 days before challenge, were given 300 rad whole-body irradiation at various times up to the day of challenge and 3 days after. Irradiated presensitized and irradiated unsensitized animals were maximally immunodepressed 1–2 weeks after exposure. The levels of resistance seen in unirradiated presensitized and in unirradiated unsensitized controls were recovered by irradiated presensitized and by irradiated unsensitized mice in about 3 and 4 weeks, respectively. Repeated injections of radiation-inactivated tumor cells were most effective in supporting the immune status of irradiated mice and in promoting an early recovery. Injections of BCG had only an insignificant effect. Injections of normal plasma was effective in reducing the immune suppression but did not promote an earlier recovery.     

Genetic control of granuloma response to oil-associated BCG cell wall vaccine in mice.

Intravenous injection of mice with BCG cell wall vaccine induces granuloma in the lung. The granuloma induced as measured by lung weight showed marked strain differences; C3H/HeMs bred in this Institute (C3H), C3HeB/FeJ, P/J and A/He were low responders, whereas C57BL/6 and AKR/He were high responders. When C57BL/6 and C3H were compared, the responsiveness appeared to be inherent in each strain of mice providing strong evidence for genetic control in this phenomenon. Breeding experiments suggested that multiple loci, including a MHC-linked locus, were involved although the role of the MHC-linked loci was marginal.     

The augmentation of tumor-specific immunity using haptenic muramyl dipeptide (MDP) derivatives

Summary Preinduction of potent haptenic muramyl dipeptide (MDP)-reactive helper T cell activity and subsequent immunization with MDP hapten-coupled syngeneic tumor cells resulted in enhanced induction of tumor-specific immunity through T-T cell collaboration between anti-MDP hapten helper T cells and tumor-specific effector T cells. The present study establishes two types of tumor-specific immunotherapy protocols utilizing helper T cells against MDP hapten cross-reactive with Bacillus Calmette Guérin (BCG). In the first model, naive normal C3H/He mice or mice in which MDP hapten-reactive helper T cells had been generated by BCG-sensitization were inoculated i.d. with syngeneic X5563 tumor cells. When both groups of mice were allowed to generate MDP hapten-modified tumor cells in the tumor mass in situ by intratumoral injection of MDP hapten, an appreciable number of growing tumors in the BCG-presensitized but not in the unsensitized group were observed to regress. In the second model, a growing X5563 tumor mass was removed by the surgical resection 9 days after the tumor implantation. Approximately 90% of C3H/He mice receiving such treatment died from tumor metastasis by about 30 days after the tumor resection. However, immunization of mice with MDP hapten-coupled X5563 tumor cells subsequent to the tumor resection resulted in an increased survival rate. Such protection from the tumor metastasis was appreciably stronger when compared to the protection obtained by immunization with MDP hapten-uncoupled tumor cells. The mice surviving in both models were also demonstrated to retain X5563 tumor-specific immunity. These results indicate that the presentation of MDP hapten-modified tumor cells to BCG-sensitized recipients results in potent tumor-specific immunity which contributes to the regression of the primary tumor or inhibition of metastatic tumor growth.This work was supported by a Grant-in-Aid for the Special Project Cancer Bioscience from the Ministry of Education, Science and Culture, Japan     

Incidence and growth of methylcholanthrene-induced tumors in mice with altered immunological status

Summary BALB/c mice were treated s.c. with 3-methyl-cholanthrene (MCA), and tumor incidence and growth were followed for 9 months. Immunological status of mice was altered by various treatments. Thymectomized, lethally irradiated, bone marrow reconstituted mice served as T-cell deficient recipients. In order to suppres natural killer (NK)-cell/macrophage functions some mice were injected with silica particles; to enhance these functions some mice were given Corynebacterium parvum (CP). Silica and CP were given simultaneously with MCA to test their influence on the presumed function of surveillance of tumor incidence, and also 2 months after MCA to test their influence on the growth of greater numbers of transformed host cells. Almost all mice developed tumors at the inoculation site and at the end of the observation period there was no difference in tumor incidence among 9 experimental groups. However, in T-cell deficient mice we observed shorter tumor duration and earlier death than in normal mice. Silica particles appeared to enhance tumor growth but the differences compared to normal controls were not significant. A single injection of CP simultaneously with MCA caused earlier tumor appearance but also slowed its growth. In contrast, CP given 2 months after MCA significantly delayed the appearance of the tumors. In regard to the tumor growth immunosuppression had stronger effects in males than in females; the opposite was true for immunostimulation treatments. We concluded that immunological status does not influence long-term tumor incidence, but that both T-cell and NK-cell/macrophage compartments strongly influence the parameters of growth of chemically induced tumors, i.e., the immune and natural resistance mechanisms do not influence the frequency of de novo arising tumors but both can slow down tumor growth.Postgraduate and pregraduate students, University of Zagreb, Faculty of Medicine, Zagreb, Yugoslavia     

Defective tumoricidal capacity of macrophages from C3H/HeJ mice

Peritoneal macrophages from C3H/HeN mice treated i.p. with T cell mitogens or viable BCG organisms were cytotoxic to syngeneic tumor cells in vitro. Macrophages from endotoxin-unresponsive C3H/HeJ mice treated with BCG or T cell mitogens, however, were not tumoricidal. Furthermore, unlike cells from C3H/HeN mice, macrophages from C3H/HeJ mice could not be activated for tumor cytotoxicity after in vitro treatment with bacterial endotoxins or with lymphokine-rich supernatants. The subnormal induction of cytotoxic macrophages after in vitro or in vivo treatments in C3H/HeJ mice appears to be a highly selective defect. Macrophage responses (yield, phagocytosis, or peroxidase staining) in inflammatory exudates induced by BCG, T cell mitogens, or heterologous serum in C3H/HeJ or C3H/HeN mice were identical. C3H/HeJ macrophages also responded normally in vitor to chemotactic lymphokines. Thus, C3H/HeJ macrophages possess a profound and selective defect in tumoricidal capacity. This defect was not dependent upon exogenous endotoxins. Defective macrophage cytotoxic responses may reflect non-LPS related functions regulated by the LPS gene.     

Induction of nitrite/nitrate synthesis in murine macrophages by BCG infection, lymphokines, or interferon-gamma

Macrophage synthesis of nitrite and nitrate after activation by BCG infection or by treatment in vitro with both T cell-derived (lymphokines (LK) or recombinant murine interferon-gamma (IFN-gamma] and bacterial (lipopolysaccharide (LPS) and heat-killed bacillus Calmette-Guerin (hk BCG] agents was studied by using macrophages from C3H/He and C3H/HeJ mice. Spleen and peritoneal macrophages isolated from BCG-infected donors that were producing nitrate continued to synthesize nitrite and nitrate in culture. LPS treatment in vitro (25 or 50 micrograms/ml) additionally increased this nitrite/nitrate synthesis. Thioglycolate-elicited macrophages from non-infected C3H/HeJ mice treated with LK also produced nitrite/nitrate, and concurrent LPS (0.1 to 50 micrograms/ml) treatment resulted in enhanced synthesis. Recombinant IFN-gamma also stimulated nitrite/nitrate synthesis by C3H/He and CeH/HeJ macrophages as did LPS (C3H/He only) and hk BCG. When given concurrently with either LPS or hk BCG, IFN-gamma enhanced C3H/He and C3H/HeJ macrophage nitrite/nitrate synthesis over that produced by macrophages treated with either LPS or hk BCG alone. Macrophages activated in vitro exhibited a 4 to 12 hr lag time before engaging in nitrite/nitrate synthesis, which then proceeded for 36 to 42 hr at linear rates. Daily medium renewal did not alter the synthesis kinetics but increased the total amount of nitrite/nitrate produced. Nitrate and nitrite were stable under the conditions of culture and when added did not influence additional macrophage synthesis. Taken together, these results indicate that T cell lymphokines and IFN-gamma are powerful modulators of macrophage nitrite/nitrate synthesis during BCG infection and in vitro, and nitrite/nitrate synthesis appears to be common property of both primed and fully activated macrophage populations.     

Studies on the recovery from tolerance to tumor antigens

Summary The present study investigates the potential of bone marrow cells from mice tolerant to tumor antigens to repopulate tumor-specific effector T cells. C3H/He mice were inoculated i.v. with 10⁶ 10000 R X-irradiated syngeneic X5563 plasmacytoma tumor cells three times at 4-day intervals. This regimen abrogated the ability of spleen cells from these mice to develop anti-X5563 cytotoxic and in vivo protective (tumor-neutralizing) T cell-mediated immunity as induced by i.d. inoculation of viable X5563 cells followed by surgical resection of the tumor. Since such suppression was induced in a tumor-specific way, this represented a state of antitumor tolerance. When bone marrow cells from normal or X5563-tolerant mice were transferred i.v. into 950 R X-irradiated syngeneic C3H/He mice, both groups of recipient mice generated anti-X5563 tumor immunity over a similar time course and to almost the same degree. Anti-X5563 tumor immunity induced in (C3H/He×C57BL/6) F1 mice which had been transferred with bone marrow cells from normal or X5563-tolerant C3H/He mice were mediated by T cells expressing the Ly phenotype of C3H/He, but not of C57BL/6, excluding the possibility that the antitumor effector cells were derived from recipient mice. It was also demonstrated that C3H/He mice which had been reconstituted with normal marrow were rendered tolerant when the tolerance regimen was started 7 weeks, but not 1 week after the bone marrow reconstitution. These results indicate that bone marrow cells from antitumor tolerant mice are not rendered tolerant to the tumor but can provide the potential to repopulate antitumor CTL and in vivo protective effector T cells.This work was supported by the Special Project Cancer-Bioscience from the Ministry of Education, Science and Culture, Japan Abbreviations used: MHC, major histocompatibility complex; CTL, cytotoxic T lymphocytes; TNP, trinitrophenyl; C, complement; TNBS; trinitrobenzene sulfonate; MMC, mitomycin C     

CD40 ligand promotes priming of fully potent antitumor CD4(+) T cells in draining lymph nodes in the presence of apoptotic tumor cells.

The presence or absence of CD4(+) T cell help can determine the direction of adaptive immune responses toward either cross-priming or cross-tolerance. It has been demonstrated that interactions of CD40-CD40 ligand can replace CD4(+) T cell help and enable dendritic cells to prime cytotoxic T cells. Here, we demonstrate that antitumor reactivity induced in regional lymph nodes (LNs) by s.c. injection of CD40 ligand (CD40L)-transduced tumor (MCA205 CD40L) showed far superior therapeutic efficacy against established brain tumors of a weakly immunogenic fibrosarcoma, MCA205, when adoptively transferred. Coinjection of apoptotic, but not necrotic parental tumor cells with CD40L-expressing tumor cells caused a strong synergistic induction of antitumor reactivity in tumor-draining LNs. Freshly isolated T cells from LNs immunized with apoptotic parental tumor cells and MCA205 CD40L were capable of mediating regression of the parental tumor in vivo. In contrast, T cells derived from LNs immunized without MCA205 CD40L required ex vivo anti-CD3/IL-2 activation to elicit therapeutic activity. On anti-CD3/IL-2 activation, cells from LNs immunized with MCA205 CD40L exhibited superior per cell antitumor reactivity. An in vitro depletion study revealed that either CD4(+) or CD8(+) T cells could mediate therapeutic efficacy but that the antitumor efficacy mediated by CD4(+) T cells was far superior. Cytosolic flow cytometric analyses indicated that priming of CD4(+) cells in LNs draining CD40L-expressing tumors was polarized to the Th1 type. This is the first report that fully potent antitumor CD4(+) T cell priming was promoted by s.c. injection of CD40L-transduced tumor in the presence of apoptotic tumor cells.     

Intrapulmonary BCG cell wall vaccination in mice

Mice of two inbred strains, Balb/c and C3H/He, were given three dosages of mycobacterium bovis BCG (5 X 10(4), 5 X 10(2) and 5 colony forming units) by either the intravenous route or by a direct intratracheal (non-aerosol) route. The magnitude of the infectivity of these inoculae given by these routes was assessed by measurement of weight changes and mycobacterial multiplication in the spleen and lung. As expected, the Balb/c strain was more susceptible to infection than the C3H/He strain. However, for both strains, infection by the intratracheal route resulted in mycobacterial counts in the lungs which were more than seven-fold higher than mycobacterial counts after intravenous challenge. Naive Balb/c mice were immunized with BCG cell wall vaccine by the intratracheal route, by the intravenous route or by subcutaneous immunization. Four weeks later mice were challenged with live BCG by the intratracheal route. Following challenge, mycobacterial counts in the lungs of mice immunized by the intratracheal route, but not in the lungs of the mice immunized by the intravenous and subcutaneous routes, were significantly lower compared to controls. These results suggest that immunization with killed BCG by the intratracheal route imparts more effective mycobacterial intrapulmonary immunity than immunization by systemic routes.     

Effects of amphetamine on the development of MTV-induced mammary tumors in female mice.

Female C3H/He mice carrying the mammary tumor virus (MTV) were monitored for mammary tumor incidence and latent periods while submitted to a daily subcutaneous injection with amphetamine (0,4 mg/kg/day). Results show that amphetamine caused an increase in incidence and a decrease in latency of tumors compared with placebo. There was also appreciated a correlation with the lethality of mice.     

Efficacy of BCG treatment after local radiotherapy in Lewis and MBL-2 tumor-bearing mice

Summary Female C57/Bl/6 mice (6–8 weeks old) bearing the Lewis or the MBL-2 tumor received localized tumor irradiation (1,600 rad; Cobalt 60) 3 days after tumor implantation. We compared the effects of the association of irradiation and immuno-BCG-F (1 mg/mouse i.v.) against three control groups (no treatment, irradiation alone, immuno-BCG-F alone). The frequency and number of BCG injections were varied in the different subgroups. Result were improved in the Lewis tumor system when BCG was injected just after the end of the irradiation. Efficiency improved with increasing number of injections (P<0.05). In the MBL-2 system, depending on the timing of BCG injections, we observed significant prolongation of survival (irradiation + BCG) over that in control groups.     

Protection against 3-methylcholanthrene-induced skin tumorigenesis in Balb/C mice by ellagic acid

Topical application of ellagic acid, a naturally occurring dietary plant phenol, to Balb/C mice resulted in significant protection against 3-methylcholanthrene (MCA)-induced skin tumorigenesis. Ellagic acid was found to be an effective inhibitor of tumor formation whether the tumor data are considered as percent mice with tumors, cumulative number of tumors, tumors per mouse or tumors per tumor bearing animal as a function of the number of weeks on test. By 8, 10, 12, 14, and 16 weeks of testing, the number of tumors per mouse in the group receiving MCA alone was 2.0, 3.4, 4.0, 4.9 and 5.3, respectively, whereas the corresponding numbers in the group receiving MCA plus 2 mumol ellagic acid were 0, 0.3, 0.4, 0.6 and 1.2, respectively. At the termination of the experiment (16 weeks) aryl hydrocarbon hydroxylase (AHH) activity in skin and liver and the extent of 3H-BP-binding to skin, liver and lung DNA were determined and both of these parameters were found to be significantly inhibited in the animals treated with ellagic acid. These results indicate that ellagic acid can inhibit the metabolism of polyaromatic hydrocarbons and modulate skin carcinogenesis induced by these chemicals.     

Tumor immunity in the mammary gland

Summary Mouse mammary tumor 410, which was derived from a spontaneously arising BALB/cf C3H mammary tumor, grows better in syngeneic BALB/c mice after injection into mammary fatpads than after injection into subcutaneous sites. This finding is consistent with the notion that the fatpad is an imunologically privileged site. However, no evidence that the mammary fatpad was immunologically privileged with respect to tumor transplantation antigens was found. Tumor cells were injected into mammary fatpads or SC. When the tumors became palpable they were surgically removed. One to three weeks later, the mice were challenged on the opposite side by injection of tumor cells either SC or into the mammary fatpad. The mice were immune after temporary growth of tumors either in the fatpad or SC. Regardless of the growth site of the immunizing tumor, the mice rejected the challenge tumor cells whether they were injected SC or into the fatpad.     

Studies on the recovery from tolerance to tumor antigens

C3H/He mice were injected i.v. with heavily X-irradiated syngeneic X5563 tumor cells three times at 4-day intervals. This regimen resulted in the abrogation of the potential to generate X5563 tumor-specific T cell-mediated immunity as induced by i.d. inoculation of viable X5563 tumor cells followed by surgical resection of the tumor, representing the tolerance induction. Although such a tumor-specific tolerant state was long-lasting, the recovery of anti-X5563 effector T cell responses was observed when the above ordinary immunization procedure was performed 6 months after the tolerance induction. The present study investigated whether the recovery from the tolerance can be accelerated by applying a helper-effector T-T cell interaction model in which enhanced anti-X5563 immunity is obtained by priming mice with BCG and by immunizing X5563 tumor cells modified with BCG cross-reactive MDP hapten (designated as L4-MDP) in the presence of anti-L4-MDP helper T cells preinduced with BCG. The results demonstrated that BCG-primed mice which received the tolerance regimen failed to generate anti-X5563 immunity when the ordinary immunization was performed 2 or 3 months after the tolerance induction. In contrast, the immunization of BCG-primed and X5563-tolerant mice with L4-MDP-coupled X5563 tumor cells at comparable timing to that of the ordinary immunization were capable of generating potent X5563-specific in vivo protective T cell-mediated immunity. As control groups, BCG-primed or unprimed tolerant mice did not develop anti-X5563 immunity when immunized with L4-MDP-uncoupled or L4-MDP-coupled tumor cells, respectively. These results indicate that immunization of BCG-primed, tumor-tolerant mice with L4-MDP-modified tumor cells results in accelerated recovery from the tumor tolerance.     

Genetics of mouse mammary tumor virus-induced mammary tumors: linkage of tumor induction to the gag gene

Retroviruses are believed to induce tumors by acting as insertional mutagens that activate expression of cellular protooncogenes. Indeed, almost 90% of mouse mammary tumor virus (MMTV)-induced mammary tumors in C3H/He mice show upregulation of Int protooncogenes. We have analyzed three different MMTV variants [MMTV(C3H), MMTV(HeJ), and a genetically engineered MMTV hybrid provirus (HP)] for tumorigenicity in mice from two distinct genetic backgrounds. All three viruses were tumor causing in BALB/cJ mice. However, only MMTV(C3H), but not MMTV(HeJ) or HP, induced mammary tumors in C3H/He mice. All of the viruses were infectious on either background and up-regulated expression of Int genes in tumors they induced. Like HP, MMTV(HeJ) was found to be a genetic recombinant between endogenous Mtv1 provirus and exogenous MMTV(C3H). Sequence comparison of MMTV variants linked the tumorigenicity of MMTV(C3H) to the gag region of the retrovirus.     

The effect of BCG on the course of experimental Chagas' disease in mice

Experiments were done to determine the effect of BCG treatment on longevity, development of parasitemia, and in vivo distribution of ⁵¹Cr-labelled trypanosomes in C3H(He) female mice infected with a Brazil strain of Trypanosoma cruzi. BCG sensitization of mice was accomplished by a single IV injection of 3·0 mg (wet weight) of BCG. Twenty-one days after BCG injection mice were infected with 5 × 10⁴ blood-form trypomastigotes. Parasitemia determinations were made on alternate days during the experiment while in vivo distribution of exogenously supplied ⁵¹Cr-epimastigotes was made in groups of BCG or PBS stimulated mice on day 15 of the T. cruzi infection.It was found that BCG sensitization had no effect on longevity or parasitemia development in T. cruzi infected C3H(He) female mice. There were, however, some differences in the in vivo distribution of parasites between BCG treated and control mice. BCG stimulated mice accumulated greater numbers of radiolabelled trypanosomes in the kidneys and small intestines while PBS treated mice were found to have greater numbers of labelled parasites in the liver. Although no significant differences were observed in longevity of BCG or PBS treated mice, it was noted that BCG treated animals which were bled for parasitemia determinations lived significantly longer than those which were merely observed for longevity.     

Lymphocytes generated by in vivo priming and in vitro sensitization demonstrate therapeutic efficacy against a murine tumor that lacks apparent immunogenicity

The adoptive transfer of sensitized lymphocytes is an effective means to mediate the regression of established tumors. However, successful therapy can only be demonstrated in animal models where tumors are intrinsically immunogenic, capable of eliciting systemic immunity. To explore the potential of this therapeutic approach to tumors of less immunogenicity, we have selected and used a murine tumor, MCA 102, for the current study because all attempts to immunize syngeneic mice failed. We report here that inoculation of mice with a mixture of tumor cells and a bacterial adjuvant, Corynebacterium parvum led to the production of sensitized, but not fully functional, lymphocytes in the draining lymph nodes (LN). These cells, termed pre-effector cells, could nevertheless further differentiate to acquire full immunologic function by an established in vitro sensitization culture method. In adoptive immunotherapy experiments, transfer of as few as 1.5 X 10(7) in vitro sensitized cells not only reduced established pulmonary MCA 102 metastases but also prolonged survival and cured tumors in a majority of the treated animals. In order to elicit pre-effector cells in vivo, inoculation with both tumor cells and C. parvum was essential. Although a broad range of numbers of MCA 102 tumor cells appeared to be effective, generation of pre-effector cells was dependent on the dose of C. parvum. We have found that a C. parvum dose of 25 micrograms was optimal, whereas higher doses of the adjuvant had suppressive effects. Analysis of the kinetics of their appearance revealed that the generation of pre-effector cells was transient. They were detectable 7 days after in vivo priming followed by a rapid decline. Furthermore, pre-effector cells were detected only in the regional draining LN. No reactivity was demonstrable in the spleen, mesenteric LN, PBL, or bone marrow. Taken together, these results expand the scope of immunotherapy by demonstrating the feasibility of manipulating a limited and obscure immune response to the MCA 102 tumor for therapeutic efficacy.     

Transmission of human T-cell leukaemia virus type I into adult mice

Human T-cell leukaemia virus type I (HTLV-I)-transformed rabbit T-cells, F647a, were intraperitoneally injected into eight 10-week-old C3H/He and C3H/HeJ mice (1 x 10(7) F647a cells/mouse), respectively. Antibody titres against HTLV-I increased to a peak at 1-3 months after injection in both C3H/He and C3H/HeJ mice. At 12 months after injection, antibody titres of two of the eight C3H/HeJ mice became undetectable, whereas those of all the C3H/He mice still ranged from 1:10 to 1:40. Sera from both seropositive C3H/He and C3H/HeJ mice reacted with HTLV-I core proteins, but not with the env protein. HTLV-I proviral sequences were detected in two of eight C3H/He mice and three of the eight C3H/HeJ mice. These results suggest that HTLV-I is able to infect an adult mouse.     

Efficacy of BCG presensitization in combination with cyclophosphamide (CY) on murine tumor growth and immunity

Summary The effect of BCG in combination with cyclophosphamide (CY) was studied in a solid tumor system in syngeneic mice. There was a marked effect of intradermal (ID) presensitization with BCG (10⁷ organisms) followed by a single intraperitoneal (IP) injection of CY (200 mg/kg) one day after the tumor inoculation on tumor suppression and tumor immunity, while there was no effect by either BCG or CY treatment alone. The optimal interval between BCG sensitization and tumor inoculation seemed to be about 3 weeks.Research supported in part by Grant-in-Aid Cancer Research from the Ministry of Health and Welfare, Japan