Inhibitory effect of locally produced and exogenous interleukin-6 on tumor growth in vivo

In order to define the potential antitumor activity of the multifunctional cytokine interleukin-6 (IL-6), retrovirus-mediated gene transfer was used to introduce and express a cDNA encoding human IL-6 in the murine fibrosarcoma cell line Fsa-R. Although these genetically modified tumor cells appeared morphologically and phenotypically identical to control Fsa-R cells and had a similar plating efficiency in vitro, they were found to exhibit greatly reduced tumorigenicity in vivo following intravenous injection into syngeneic recipients. Exogenous IL-6 was shown to produce a similar inhibition of tumor growth in the lung if administered intraperitoneally. In contrast, tumor growth in subcutaneous sites was inhibited only if the tumor cells were engineered to express IL-6 locally, or if IL-6 was administered intratumorally. Intraperitoneal injection of IL-6 had no inhibitory effect. Tumors that did grow from IL-6-producing tumor cell inocula in subcutaneous sites were found to contain large numbers of macrophages. These results demonstrate that the antitumor activity of systemically administered IL-6 varies depending on the site of tumor growth and suggest an important role for IL-6 in the recruitment, proliferation and/or survival of tumor-associated macrophages.Supported by grants from the B. C. Health Care Research Foundation (BCHRF), the National Cancer Institute (NCI) and the National Cancer Institute of Canada (NCIC). G.J.D. is a Research Scientist of the National Cancer Institute of Canada (NCIC). R.S.L. is a RSNA Research and Education Fund Scholar     

Inhibition of growth of hamster tumor cells in vitro by pyrrolidone carboxylic acid in a glutamine-dependent system

Summary Pyrrolidone carboxylic acid, which is formed spontaneously when glutamine is incubated at 37°C in a phosphate or bicarbonate medium, was found to inhibit growth of a line of hamster tumor cells which required glutamine for survival and growth. This investigation was supported in part by Grant CA-02568 from the National Cancer Institute, Bethesda, Maryland 20014.     

Effect of allogeneic tumor cells,interleukin-2 and interleukin-6, on the growth of subcutaneous syngeneic tumors

In the present study we demonstrate the ability of allogeneic M3 tumor cells to induce an antitumor response against the syngeneic tumor, when injected locally together with syngeneic B16 melanoma cells. The replacement of the allogeneic tumor cells with either syngeneic or allogeneic splenocytes had no effect on the growth of the syngeneic tumor. Systemic administration of both interleukin-2 (IL-2) and IL-6 did not affect the antitumor response induced by allogeneic tumor cells. When mice, previously injected with B16 and M3 cells, were rechallenged subcutaneously with B16 tumor cells at a different anatomical site, an inhibitory effect in some, but not all, experiments was observed. Systemic injections of either IL-2 or IL-6 did not alter the antitumor effects of the allogeneic and syngeneic tumor-cell mixtures. The significance of our results in developing immunotherapy modalities based on active immunization with allogeneic tumor cells and selected cytokines is discussed.This study was supported by a grant from the Israeli Cancer Association     

Macrophages and resistance to tumors

Summary Delayed-type hypersensitivity (DTH) reactions in mouse feet were depressed by irradiation and by treatment with carrageenan, niridazole, or reserpine. Specific resistance of immunized mice to footpad challenge with a syngeneic methylcholanthrene-induced fibrosarcoma was also depressed by irradiation, carrageenan, niridazole, and reserpine. Growth of the tumor in the feet of normal mice was unaffected by irradiation or niridazole. It could be inhibited or enhanced by carrageenan treatment, depending on the dose of tumor cells injected. Paradoxically, treatment with reserpine inhibited tumor growth in the feet of nonimmune mice. It is suggested that: (a) specific, acquired resistance to this tumor is strongly akin to DTH; (b) mice offer some natural resistance to this tumor; (c) the establishment of an isograft of this tumor may depend on the occurrence of some degree of inflammation.This work was carried out pursuant to Research Contract NO1-CB-63973 with the U.S. National Cancer Institute. It was supported in part by a grant from the Australian National Health and Medical Research Council     

Cell transformation by viruses

Summary This paper describes some current work pertaining to transformation of cells by oncogenic viruses. Part I includes: (1) the effect of a deoxyribonucleic acid (DNA) tumor virus (SV40) on the antigenic characteristics of transformed cells; (2) in vitro and in vivo methods of detecting virus-specific surface antigens; (3) the role that the host cell may play in the expression of virus-coded antigens; and (4) the presence of virus-induced antigens as a possible mechanism of the apparent nononcogenicity of certain virus variants. Part II discusses (1) the physicochemical properties of the nucleic acid of a ribonucleic acid (RNA) tumor virus-the Moloney sarcoma-leukemia virus (MSV-MLV) complex —(2) a preliminary analysis of viral RNA replication in cells transformed by MSV-MLV, and (3) application to human tumors. Supported in part by Research Grant CA 04600 and by Research Contract PH 43-68-678 within the Special Virus-Cancer Program, National Cancer Institute, National Institutes of Health. Recipient of Research Career Development Award 5-K3-CA 38,614 from the National Cancer Institute, National Institutes of Health     

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     

The addition of interleukin-2 to cyclophosphamide therapy can facilitate tumor growth of B16 melanoma

The role of interleukin-2 (IL-2) on tumor growth of B16F10 melanoma cells was assessed in two sets of mice with different immune status: normal (immunocompetent) mice and immunodeficient mice. The two sets of animals were treated with cyclophosphamide (CY) or IL-2 alone or with a combined therapy of CY+IL-2. On days 6 and 10 after tumor cell injection, we evaluated the incidence of hepatic B16 melanoma metastases and the percentage of hepatic volume occupied by metastatic tissue. We observed that the CY alone (300 mg/kg, days 3 and 8 post-tumoral inoculation) significantly reduced tumor growth in all treated mice; however, CY proved more effective in normal recipients than in immunodeficient hosts. On the other hand, whereas administration of IL-2 alone (10⁵ IU daily, from day 3 to day 7) in immunocompetent mice significantly reduced tumor growth on days 6 and 10, in immunodeficient mice, no significant differences were observed in tumor growth either on the 6th or on the 10th day, in comparison to control groups. Finally, when the combined CY+IL-2 therapy was administered, an antisynergistic effect between these therapeutic agents was achieved both in normal and in immunodeficient mice. Thus, the addition of low-dose IL-2 (25×10³ IU daily, from day 4 to day 7) to high-dose CY (300 mg/kg, days 3 and 8) significantly increased tumor growth in both the early and later periods, compared to the effect of CY alone. It is concluded that exogenous IL-2 can facilitate tumor growth of B16 melanoma cells in vivo.     

Effects of defined medium,fetal bovine serum,and human serum on growth and chemosensitivities of human breast cancer cells in primary culture: Inference for in vitro assays

Summary We compared the effects of defined medium, fetal bovine serum (FBS) and human serum (HuS) on the growth and responses to chemotherapeutic agents of human breast cancer cells in primary culture. Normal and tumor tissues were dissociated to small aggregates and single cells and seeded onto collagen-gel-coated wells in defined medium or medium supplemented with 5% FBS or 5% HuS. In all cases examined, defined medium and medium containing HuS were superior to medium containing FBS in supporting growth of both normal and tumor cell cultures. However, cultures in defined medium showed an initial cell loss. Cells from the same tumor cultured in different media varied in their responses to chemotherapeutic agents. In light of these results, medium supplemented with HuS, which promoted attachment of these cells in culture and stimulated their growth, should be the most appropriate nutrient environment for determining the effects of therapeutic agents on cells as it most closely resembles the in vivo situation. Because there were also variations in growth rates and chemosensitivities of tumor cells cultured in different human serum samples, we suggest that optimal conditions in which to culture these cells include the serum of the patient whose tumor is removed. This serum may provide host factors that influence cell growth and interact with exogenous factors. This work was supported by a grant from the National Cancer Institute of Canada and funds contributed by Mr. B. T. Wharton in memory of his wife, Nadia. J. T. Emerman is a research scholar of the National Cancer Institute of Canada.     

Effects of the interferon-inducer ABPP on colon cancer in rats; importance of tumor load and tumor site

Summary ABPP (2-amino-5-bromo-6-phenyl-4-pyrimidinone) is a pyrimidinone with known interferon-inducing, natural killer (NK) cell activity enhancing, antiviral and antitumor properties in several animal species. Its effect on CC531, a dimethylhydrazine-induced, transplantable, weakly immunogenic adenocarcinoma of the colon in WAG rats, was studied. ABPP was found to have no direct cytotoxic effect on CC531 cells in vitro. When small cubes of tumor of equal weight were implanted under the renal capsule, administration of 250 mg/kg of ABPP i. p. on day 0 and +1 led repeatedly to significant (p<0.02 up to p<0.001) inhibition of tumor growth, when measured on day +7. Lower doses or a single dose of ABPP did not achieve this effect. Late administration (on day +6 and +7) of 250 mg/kg of ABPP in this model was found to have no effect on tumor growth when measured on day +13. When 5×10⁵ tumor cells were injected in the portal vein, administration of 250 mg/kg of ABPP i.p. on day 0 and +1 reduced significantly (p=0.002) the number of liver metastases, when counted on day +30. Survival in this group was significantly prolonged (p<0.01). However when ABPP was given on day +6 and +7, significantly more (p<0.02) metastases in the liver were counted on day +30. The results show a significant antitumor effect of ABPP against tumor CC531 in the subrenal capsule assay (SRCA) model as well as in the liver metastasis model when administered at the time of tumor inoculation. Late administration of ABPP did not inhibit tumor growth in the SRCA and significantly enhanced the development of liver metastases. The role of timing, tumor site, and the mechanisms by which this dual outcome of immunotherapy with ABPP is mediated are discussed. The results of these experiments may have important implications for the design of clinical studies with ABPP.This study was supported in part by a grant from The Upjohn Company, Kalamazoo, Michigan, USA     

Local injections of OK432 can help the infiltration of adoptively transferred CD8+ T cells into the tumor sites and synergistically induce the local production of Th1-type cytokines and CXC3 chemokines

The effect of local injections with streptococcal preparation OK432 on the antitumor effect induced by adoptive immunotherapy (AIT) was investigated. Draining lymph node cells on day 14 after B7-P815 inoculation were used for AIT after in vitro stimulation. AIT on days 7 and 10 showed no effect on the growth of s.c. established P815 mastocytoma, but local injections with OK432 into the tumor sites on days 3, 6 and 9 resulted in a moderate antitumor effect. On the other hand, the combination therapy significantly suppressed tumor growth, and the tumor-bearing mice survived longer than those receiving only one of the treatment modalities. The significant infiltration of CD4⁺ or CD8⁺ T cells and multiple necrosis in the tumor sites were observed only when the tumor-bearing mice were treated with the combination therapy. In addition, a transfer experiment using labeled effector cells revealed these infiltrated CD8⁺ T cells and CD4⁺ T cells to be derived from the donor and the host respectively. More importantly, the combination therapy clearly led to higher expression of the mRNA for Th1-type cytokines and CXC3 chemokines in the tumor sites than resulted from each of the treatment modalities alone. Collectively, these results indicate that local injections with OK432 can help the infiltration of adoptively transferred CD8⁺ T cells into the tumor sites and synergistically induce the local production of the Th1-type cytokines and CXC3 chemokines. Received: 3 April 2000 / Accepted: 5 May 2000     

Synergistic anti-tumor effect of glycosylphosphatidylinositol-anchored IL-2 and IL-12

BACKGROUND: Preclinical and clinical studies have demonstrated that interleukin 2 (IL-2), interleukin 12 (IL-12), and some other cytokines, play important roles in activating host immune responses against tumor growth. However, severe side effects caused by systemic high-dose administration of these cytokines limit their clinical application. In our previous study, local high doses of IL-2 were achieved by a GPI-anchoring technology; therefore, it will be interesting to know if this technology works for other cytokines. METHODS: A fusion gene containing murine IL-12 and the glycosylphosphatidylinositol (GPI) anchor signal sequence was generated and transfected into the murine melanoma tumor cell line B16F0 either alone or together with a vector encoding GPI-anchored IL-2. The GPI-anchored cytokine expression of the selected stable clones was assayed in vitro by ELISA and their anti-tumor effects were analyzed in vivo by tumor lymphocyte infiltration and tumor growth studies. RESULTS: GPI-anchored IL-12 was successfully expressed on the cell surface as indicated by FACS analysis and IL-12 ELISA assay. The GPI-anchored IL-12 enhanced lymphocyte infiltration and significantly inhibited tumor growth. More importantly, when GPI-anchored IL-12 and GPI-anchored IL-2 were co-delivered, a synergistic anti-tumor effect was observed in both subcutaneous and intravenous tumor models. CONCLUSIONS: GPI anchorage of cytokines represents a new approach to locally deliver high doses of cytokines without the severe adverse effects normally accompanied with systematic high-dose administration of these cytokines.     

Genetic and biochemical studies on the suppression of and a recovery from the tumorous state in higher plants

Summary Four neoplastic diseases of plants: crown gall, which is caused by Ti plasmid DNA; Black's wound tumor disease by an RNA virus; the Kostoff genetic tumors by chromosomal imbalance; and habituation, which results from a spontaneous activation of select biosynthetic systems, have been analyzed and compared. It has been found that both the development of a capacity for autonomous growth and the nature of the heritable cellular change that underlies tumorigenesis are similar in the four instances. All develop a capacity for autonomous growth as a result of the persistent activation of select biosynthetic systems, the products of which are concerned with cell growth and division. That the persistent activation of these biosynthetic systems does not involve heritable changes of an irreversible type is indicated by the finding that a reversal of the neoplastic state occurred in three of the test systems. Since the tumor cells in these instances were found to remain totipotent the results suggest that whether the normal or tumor phenotype is expressed is determined by how the genetic information is regulated in a cell. Regulation appears to be accomplished in part through positive feedback control mechanisms. Foreign genetic information could act either in a regulatory manner to persistently activate normal biosynthetic systems or it could code for one or more essential but normally limiting substance(s) and thus replace a substance(s) that in the case of the Kostoff tumors or habituation is specified by host cell genes, or it could do both. In either case, the foreign genetic information can be regulated in much the same manner as are the host cell genes to give rise to either the normal or tumor phenotype. Presented in the symposium on Gene Transfer, Differentiation and Neoplasia in Plant and Animal Cells at the 30th Annual Meeting of the Tissue Culture Association, Seattle, Washington, June 10–14, 1979. This symposium was supported in part by Grant CA 26748 from the National Cancer Institute, DHEW, and Grant RD-67 from the American Cancer Society. Certain of the investigations described above were supported in part by Grant Number CA-13808, awarded by the National Cancer Institute, U.S. Department of Health, Education, and Welfare, in which the author is the coprincipal investigator.     

Reduced tumorigenicity of A-10 adenocarcinoma in the presence of immunogenic A-10 tumor cells

Summary The highly tumorigenic A-10 adenocarcinoma caused progressive tumor growth and death of syngenic A/J mice, whereas cultured A-10 cells did not cause tumors in all mice. The mixture of in vivo-grown and cultured A-10 tumor cells resulted in either progressive tumor growth or tumor rejection, depending upon the relative proportion of the two cell types. Expression of cell-surface carbohydrates was quantitated using cell-microbead, lectin-induced agglutination. The immunogenic, cultured A-10 tumor possessed a marked increase in agglutinability, compared to the in vivo-grown tumor. The results are consistent with the concept that the immunogenic properties of murine adenocarcinoma are closely associated with properties of the cell-surface.Supported, in part, by a research contract from the National Cancer Institute, USA     

ADAM17 Silencing in Mouse Colon Carcinoma Cells: The Effect on Tumoricidal Cytokines and Angiogenesis

ADAM17 (a disintegrin and metalloprotease 17) is a major sheddase for numerous growth factors, cytokines, receptors, and cell adhesion molecules and is often overexpressed in malignant cells. It is generally accepted that ADAM17 promotes tumor development via activating growth factors from the EGF family, thus facilitating autocrine stimulation of tumor cell proliferation and migration. Here we show, using MC38CEA murine colon carcinoma model, that ADAM17 also regulates tumor angiogenesis and cytokine profile. When ADAM17 was silenced in MC38CEA cells, in vivo tumor growth and in vitro cell motility were significantly diminished, but no effect was seen on in vitro cell proliferation. ADAM17-silencing was accompanied by decreased in vitro expression of vascular endothelial growth factor-A and matrix metalloprotease-9, which was consistent with the limited angiogenesis and slower growth seen in ADAM17-silenced tumors. Among the growth factors susceptible to shedding by ADAM17, neuregulin-1 was the only candidate to mediate the effects of ADAM17 on MC38CEA motility and tumor angiogenesis. Concentrations of TNF and IFNγ, cytokines that synergistically induced proapoptotic effects on MC38CEA cells, were significantly elevated in the lysates of ADAM17-silenced tumors compared to mock transfected controls, suggesting a possible role for ADAM17 in host immune suppression. These results introduce new, complex roles of ADAM17 in tumor progression, including its impact on the anti-tumor immune response.     

Immune reconstitution prevents metastatic recurrence of murine osteosarcoma

Primary tumors developing in immunocompetent hosts escape immunosurveillance by acquiring immune evasive properties. This raises the prospect that metastases derived from such tumors will also evade immunity. To investigate whether immune surveillance plays a role in preventing metastases, we studied a murine model which mimics the clinical progression of osteosarcoma: primary tumor growth in the lower extremity, amputation, minimal residual disease followed by the development of overt metastases. K7M2 implants readily escaped immune surveillance since normal BALB/c mice, T cell deficient SCID and T/NK cell deficient SCID-bg mice showed no difference in the rate of growth of primary osteosarcomas. However, both SCID and SCID-bg mice had higher rates of metastases than immunocompetent mice. Similarly, immune reconstitution following transfer of naive T cells to SCID or SCID-bg mice did not impact primary tumor growth, but significantly diminished metastatic recurrence. T cells in osteosarcoma bearing mice produced IFNγ in response to tumor and IFNγ production by immune reconstituting T cells was required to prevent metastases. These results demonstrate an important role for T cell based immune surveillance in preventing metastases, even when metastases develop from tumors that adeptly evade immunosurveillance. The results further suggest that T cell depleting cancer therapies may eliminate beneficial immune responses and that immune reconstitution of lymphopenic cancer patients could prevent metastatic recurrence of solid tumors. By acceptance of this article, the publisher or recipient acknowledges right of the U.S. Government to retain a nonexclusive, royalty-free license in and to any copyright covering the article. The contents of this publication do not necessarily reflect the views or policies of the Department of Health and Human Services, nor does mention of trade names, commercial products, or organizations imply endorsement by the U.S. Government. Animal care was provided in accordance with procedures outlined in the “Guide for the Care and Use of Laboratory Animals” (NIH Pub. No. 86-23, 1996). This project was funded in whole or part with funds from the National Cancer Institute, National Institutes of Health, under Contract No. NO1-CO-56000.     

Effects of inflammatory factors on mesenchymal stem cells and their role in the promotion of tumor angiogenesis in colon cancer

Mesenchymal stem cells (MSCs), which are modulated by cytokines present in the tumor microenvironment, play an important role in tumor progression. It is well documented that inflammation is an important part of the tumor microenvironment, so we investigated whether stimulation of MSCs by inflammatory cytokines would contribute to their ability to promote tumor growth. We first showed that MSCs could increase C26 colon cancer growth in mice. This growth-promoting effect was further accelerated when the MSCs were pre-stimulated by inflammatory factors IFN-γ and TNF-α. At the same time, we demonstrated that MSCs pre-stimulated by both inflammatory factors could promote tumor angiogenesis in vivo to a greater degree than untreated MSCs or MSCs pre-stimulated by either IFN-γ or TNF-α alone. A hen egg test-chorioallantoic membrane (HET-CAM) assay showed that treatment of MSC-conditioned medium can promote chorioallantoic membrane angiogenesis in vitro, especially treatment with conditioned medium of MSCs pretreated with IFN-γ and TNF-α together. This mechanism of promoting angiogenesis appears to take place via an increase in the expression of vascular endothelial growth factor (VEGF), which itself takes place through an increase in signaling in the hypoxia-inducible factor 1α (HIF-1α)-dependent pathway. Inhibition of HIF-1α in MSCs by siRNA was found to effectively reduce the ability of MSC to affect the growth of colon cancer in vivo in the inflammatory microenviroment. These results indicate that MSCs stimulated by inflammatory cytokines such as IFN-γ and TNF-α in the tumor microenvironment express higher levels of VEGF via the HIF-1α signaling pathway and that these MSCs then enhance tumor angiogenesis, finally leading to colon cancer growth in mice.     

Therapeutic application of various immunostimulators on the L2C guinea-pig leukemia

Summary Immunostimulators such as Corynebacterium parvum (C. parvum), Bacillus Calmette-Guerin (BCG), pyran copolymer, and glucan were examined in the guinea pig L ₂ C lymphoblastic leukemia model to determine their capacity for therapeutic modulation of the immune response of the host toward controlling leukemic cell proliferation. The dose, route, and frequency of administration of the stimulators were also evaluated as a function of time in order to obtain an optimal antileukemic effect. Results indicated that only C. parvum and BCG were capable of significantly increasing host survival when given 1 day after an inoculation of 1.5×10 ⁴ viable leukemic cells. Administration of BCG or C. parvum, alone or in combination with irradiated blast cells on either days 4 or 7, was totally ineffective in prolonging survival. In the majority of cases, enhanced leukemic growth was observed on these days. The combination of BCG and/or C. parvum with irradiated syngeneic blast cells given 24 h after leukemia inoculation promoted a synergistic response with a significant increase in median survival time and a number of long-term survivors.This work was supported by contract N01-CP-53566 within the Virus Cancer Program of the National Cancer Institute     

Cytokine profile of Ehrlich ascites tumor treated with Bothrops jararaca venom

We previously demonstrated that Bothrops jararaca venom (BjV) has an antitumor effect on Ehrlich ascites tumor (EAT) cells and induces an increase of polymorphonuclear leukocytes in early stages of tumor growth. It has been reported that this venom presents an important inflammatory effect when inoculated in animal models and in human snakebites, and that cytokine levels have been detected in these cases. To evaluate whether the cytokines can be involved with the suppression of the tumoral growth, we evaluate the cytokine profile in the peritoneal cavity of mice inoculated with EAT cells and treated with BjV. Swiss mice were inoculated with EAT cells by the intraperitoneal route and treated with BjV venom (0.4 mg/kg, intraperitoneally), on the 1st, 4th, 7th, 10th, and 13th day. Mice were evaluated for cytokine levels on the 2nd, 5th, 8th, 11th and 14th day. Analysis was performed using an enzyme-linked immunosorbent assay for interleukin (IL)-1alpha, IL-2, IL4, IL-6, IL-10, IL-13, and tumor necrosis factor-alpha (TNF-alpha) levels in the peritoneal washing supernatant. Results were analyzed statistically by the Kruskal-Wallis and Dunn's tests at the 5% level of significance. We observed that EAT implantation induces IL-6 production on the 11th and 14th days of tumor growth, IL-10 on the 11th day and TNF-alpha on the 14th day. The treatment with BjV suppresses production of these cytokines. In addition, IL-13 was produced by animals that were inoculated only with venom on the 11th and 14th days, and by the group inoculated with EAT cells and treated with venom on the 2nd and 14th days. Furthermore, we suggest that the IL-6 detected in the present study is produced by the EAT cells and the suppression of its production could be associated with the antitumor effect of BjV.     

Quantitative characterization of domes in primary mouse mammary epithelial tumor cell cultures

Summary Dome populations from primary cultures of mouse mammary tumor cells were quantitatively studied in regard to size, distribution, density and the area occupied by light-diffusion photography and image analysis. The effects of fetal bovine serum, insulin and hydrocortisone were analyzed. Quantitative characterization documented dome diameter (mode diameter 0.26 to 0.52 mm), dome area occupied (average 23%, maximum 38.7%), and density (average 78 domes per cm², maximum 117 domes per cm²) for standard culture conditions. Insulin and hydrocortisone had a primary effect on dome density whereas 15% fetal bovine serum had a minimal effect. However, insulin and hydrocortisone had a synergistic optimal effect on dome population. Time-lapse cinematography revealed that the dome population is not static, but a very dynamic one. Domes underwent irregular pulsations of expansion and contraction. Dome enlargement was either by a series of expansions and contractions, by lateral involvement of other cells, or by coalescence of two or more domes. Domes have been considered to be the in vitro counterpart of the in vivo acinus of the mouse mammary gland. However, quantitative dome population characterization has not been available. Dome analysis by light-diffraction photography and image analysis lends itself towards correlative studies of domes and their differentiative products. Supported in part by Public Health Service Contract NO1-CP 61013 within the Virus Cancer Program of the National Cancer Institute and by Public Health Service Training Grant CA05245 from the National Cancer Institute.     

Effect of low-dose cyclophosphamide therapy on specific and nonspecific T cell-dependent immune responses of spleen cells from mice bearing large MOPC-315 plasmacytomas

Summary Some T cell-dependent immune parameters were examined in mice bearing a large MOPC-315 plasmacytoma before and after treatment with a low dose (15 mg/kg) of CY. Prior to CY therapy, spleen cells from mice bearing a large MOPC-315 tumor were depressed in their ability to generate an in vitro cytotoxic response to the MOPC-315 tumor, to a different syngeneic plasmacytoma, MOPC-104E, and to an allogeneic thymoma, EL4. The spleen cells of these mice were also depressed in their ability to proliferate in response to the T cell mitogen PHA. Following CY therapy, the spleen cells generated an enhanced anti-MOPC-315 cytotoxic response by day 2, and the level of this response continued to increase so that by day 7, it was greatly enhanced and was much greater than the response of normal spleen cells. The recovery of the cytotoxic responsiveness to the antigenically related MOPC-104E tumor after CY therapy followed a similar pattern. In contrast, the spleen cells of these animals remained depressed in their cytotoxic response to the antigenically unrelated EL4 thymoma for at least 11 days after CY therapy. Although the anti-EL4 response recovered by day 14, the level of antitumor cytotoxicity generated did not exceed that generated by normal spleen cells. The PHA response remained greatly depressed in CY-treated MOPC-315 tumor bearers, even 14 days after the chemotherapy. Thus, at a time following low-dose CY therapy, when potent T cell-dependent antiplasmacytoma immunity had completed the eradication of a large MOPC-315 tumor burden not eliminated through the direct effect of the drug, the T cell-dependent response to an unrelated tumor and to PHA remained depressed.Supported by United Public Health Service Research Grant #CA-30088 and by Training Grant #CA-09318 from the National Cancer InstitutePresented in part at the 77th annual meeting of the American Association of Cancer Research, May 7–10, 1986In partial fulfillment of the requirements of the Graduate College for the Doctor of Philosophy degree Abbreviations used: CY, cyclophosphamide; FBS, fetal bovine serum; FITC, fluorescein isothiocyanate; PHA, phytohemagglutinin