Expression of mouse embryonic epitope TEC-2 on human carcinoma-derived cell lines and characterization of its glycoprotein carriers.

Monoclonal antibody TEC-02, raised against mouse embryonal carcinoma cells, has been shown to react with murine preimplantation embryos and with a very limited number of adult mouse tissues. The target epitope, TEC-2, is a carbohydrate carried in mouse embryonal carcinoma cells by large glycoprotein-bound glycan. We report here the expression of TEC-2 epitope on human carcinoma-derived cell lines, HeLa and HS, and the properties of its carbohydrate carriers. Immunolabeling of Nonidet P-40 lysates of HeLa cells separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed that TEC-2 antigens are polydispersed glycoconjugates of high molecular weight (mostly above 100,000). TEC-2 antigens detected by the two-site sandwich assay, in which the antigen is immobilized and detected with the same antibody, had a slightly higher molecular weight than those detected by the solid-phase assay. This suggests heterogeneity in the number of TEC-2 epitopes per carrier molecule. When the cells were lysed by Triton X-114 and the detergent and aqueous phases were separated by warming and centrifugation, most of the TEC-2 antigenic activity was found in the aqueous phase. TEC-2 antigens isolated by indirect precipitation from [3H]galactose-labeled HeLa cells were degraded by extensive pronase digestion or mild alkaline treatment to glycopeptides or oligosaccharides of low molecular weight. Thus, TEC-2 epitope in human HeLa cells is carried by carbohydrates of only several monosaccharide units. TEC-02 antibody was also found to bind to Tamm-Horsfall glycoprotein isolated from human urine and its binding was enhanced by desialylation. Combined data indicate that TEC-02 antibody recognizes the GalNAc beta 1----4Gal beta 1----4 structure which may be carried on different types of molecule, according to the site of their synthesis.

Immunotherapeutic efficacy of vaccines generated by fusion of dendritic cells and HPV16-associated tumour cells.

Utilization of vaccines generated by fusion of dendritic cells and tumour cells is a promising approach to tumour immunotherapy. We have examined the therapeutic efficacy of vaccines generated by fusion of HPV16-associated tumour cells TC-1 with syngeneic and allogeneic dendritic cells. Locally administered hybrid cells generated by fusion of MHC class I+ TC-1 cells and syngeneic DC inhibited the growth of MHC class I+ TC-1 tumours, but not the growth of MHC class I- TC-1/A9-derived tumours. The growth of TC-1 tumours was also inhibited by hybrids generated by fusion of TC-1 cells and allogeneic DC. The therapeutic efficacy was enhanced by co-administration of the vaccine with synthetic immunostimulatory ODN CpG 1826.

Local cytokine treatment of HPV16-associated tumours results in inhibition of their lung metastases.

Experiments were designed to examine whether local cytokine therapy of subcutaneous (s.c.) tumours results in inhibition of their lung metastases. Moderately immunogenic, major histocompatibility complex (MHC) class I and II negative. B7 negative, metastasizing murine carcinoma MK16 transplantable in syngeneic mice was obtained by co-transfection of human papilloma virus type 16 (HPV 16) E6/E7 and activated H-ras oncogene plasmid DNA into C57BL/6 kidney cells. After s.c. transplantation of the malignantly converted MK16 cells, the majority of the transplanted mice developed lung metastases; the number and size of the lung metastases increased with the increasing size of the s.c. tumour. Therapy of 5-day MK16 tumours by peritumoral administration of recombinant interleukin-2 (IL-2) and recombinant interleukin-12 (IL-12) inhibited growth of the s.c. MK16 tumour transplants and reduced the number of MK16 lung metastases. To investigate the antimetastatic effect of IL-2 and IL- 12 in a clinically more relevant setting, surgical minimal residual tumour disease was utilized. Subcutaneously growing MK16 carcinomas, 8-12 mm in diameter, were removed on day 30 and the operated mice were injected with IL-2 or IL- 12 on days 35-39 and 42-46 at the site of the operation. Treatment with IL-2 significantly reduced the percentage of MK16 tumour recurrences as well as the number of lung metastases, whereas the effect of IL- 12 was substantially weaker and statistically insignificant.

Immunotherapy of cancer using local administration of lymphoid cells transformed by IL-2 cDNA and constitutively producing IL-2.

Peritumoral administration of X63-m-IL-2 cells transformed by IL-2 cDNA and constitutively producing large quantities of recombinant IL-2 mediated regression of X63-Ag8.653 plasmocytoma and MC14 sarcoma transplanted in syngeneic mice. Injections of the IL-2-producing cells containing an inserted, modified IL-2 gene effectively inhibited tumour growth also in allogeneic recipients. Activation of murine spleen cells in vitro by co-cultivation with X63-m-IL-2 cells gave rise to lymphokine-activated killer (LAK) cell populations cytotoxic for the X63-Ag8.653 plasmocytoma and MC14 sarcoma. The results suggest that peritumoral administration of lymphoid cells transformed with IL-2 cDNA and constitutively producing IL-2 in the immediate tumour vicinity is sufficient for the effective activation of local IL-2-dependent tumour defence mechanisms and, therefore, can be considered a novel, genetic approach to the immunotherapy of cancer.

Defect in lectin-induced interleukin 2 production by peripheral blood lymphocytes of patients with invasive urinary bladder carcinoma.

The production of interleukin 2 (IL-2) by phytohaemagglutinin (PHA)-stimulated peripheral blood mononuclear cells (PBMC) from 21 patients with transitional cell carcinoma of the urinary bladder (BTCC) and 16 control blood donors was measured with a solid phase enzyme immunoassay based on the dual antibody immunometric sandwich principle. PBMC from patients with invasive BTCC (grade III-IV) showed a defect in the production of IL-2. The concentration of IL-2 in the supernatants of PBMC cultures from these patients was substantially lower (0.4 +/- 0.1 U/ml) than that observed in the supernatants of PBMC cultures from patients with non-invasive BTCC, grade II (1.5 +/- 0.7 U/ml), and from tumour-free controls (1.4 +/- 0.8 U/ml). These results suggest an immune dysfunction based on quantitatively impaired IL-2 production in patients with invasive BTCC and indicate that exogenous IL-2 could be used as an immunological response modifier for the treatment of these patients.

Thy-1 epitopes are expressed on murine myeloid leukemia and reticulum sarcoma cells.

Expression of Thy-1.2 specificities in cells from 29 primary spontaneous leukemias of random-bred ICR Swiss mice was examined by cell membrane and cytoplasmic immunofluorescence with monoclonal HO-13-4 antibody [1]. The Thy-1.2 epitopes were detected in all thymic lymphomas and were absent in the lymphomas of non-thymic origin. Unexpectedly, the Thy-1.2 epitopes were also detected in 71% (5/7) of myeloid leukemias and 40% (4/10) of reticulum cell sarcomas examined.

Local administration of cells containing an inserted IL-2 gene and producing IL-2 inhibits growth of human tumours in nu/nu mice.

We have prepared a retroviral expression construct, pPS-IL-2, in which human IL-2 cDNA has been inserted into the polylinker region, and have used the retroviral vector to introduce the functional IL-2 gene into a fibroblast cell line, RAT-1. Peritumoral administration of IL-2-producing RAT-1 cells into congenitally athymic (nu/nu) mice carrying subcutaneous transplants of human carcinoma cells inhibited the growth of the human tumour xenografts.

Use of IL-2 gene transfer in local immunotherapy of cancer.

Insertion of functional interleukin-2 (IL-2) gene into a plasmacytoma cell line X63-Ag8.653 substantially reduced tumorigenicity of the resulting cloned cells, designated as X63-m-IL-2. Peritumoral administration of the X63-m-IL-2 cells, producing constitutively large quantities of IL-2, resulted in regressions of established X63-Ag8.653 plasmacytomas growing in the peritoneal cavity of syngeneic mice. In vitro activation of BALB/c spleen cells by co-culture with X63-m-IL-2 cells or their supernatants gave rise to cytotoxic lymphocytes with lymphokine-activated killer (LAK) activity against syngeneic X63-Ag8.653 plasmacytoma and other tumor targets. In contrast, peritumoral administration of X63-Ag8.653 cells carrying an inserted interleukin-4 (IL-4) gene (designated X63-m-IL-4 cells) and producing constitutively large quantities of IL-4 did not result in a therapeutic effect. Moreover, the admixture of the X63-m-IL-4 and X63-m-IL-2 cells substantially diminished the X63-m-IL-2 cell-mediated therapeutic effect. Similarly, IL-4-containing supernatants generated from X63-m-IL-4 cell cultures substantially diminished LAK activation by X63-m-IL-2 cell produced supernatants.

Irradiated IL-2 gene-modified plasmacytoma vaccines are more efficient than live vaccines.

The effect of irradiation on the therapeutic efficacy of IL-2 gene-modified plasmacytoma cells used as a vaccine in the immunotherapy of parental murine plasmacytoma X63-Ag8.653 was examined. Local administration of the IL-2-secreting plasmacytoma irradiated with a dose of 50 Gy inhibited i.p. plasmacytoma growth more effectively than the administration of non-irradiated, live cell vaccines. Whereas the vaccination with the live cell vaccine could substantially prolong the survival of the tumour-bearing mice but did not significantly induce tumour regressions, the irradiated vaccines could substantially increase the number of tumour-free animals. The irradiated vaccines produce higher amounts of IL-2 than the live cell vaccines both in vitro and in vivo. Depletion of CD4+ and CD8+ effector cells with monoclonal antibodies has significantly decreased the effect of the vaccination. It can be concluded that both, CD4+ and CD8+ T lymphocytes are required for effective IL-2 gene therapy of the X63-Ag8.653 plasmacytoma and that the higher effect of the irradiated vaccines is probably due to their higher IL-2 production.

Prophylactic, therapeutic and anti-metastatic effects of BMDC and DC lines in mice carrying HPV 16-associated tumours.

Oncogenic, moderately immunogenic MK16/1/IIIABC (MK16) cells were previously established by co-transfection of HPV 16 E6/E7 and activated H-ras oncogene DNA into C57BL/6 kidney cells. Subcutaneous transplantation of the MK16 cells produced progressively growing neoplasms which metastasized spontaneously to lungs. In this communication we report that prophylactic administration of bone marrow-derived dendritic cells (BMDC) as well as dendritic cell (DC) lines DC2.4 and JAWS II at the site of subsequent MK16 tumour transplants inhibited tumour growth and reduced the number of lung metastases. Similarly, in therapeutic experiments, administration of BMDC and DC lines at the site of the growing MK16 tumours or at the site of MK16 tumour residua after surgery inhibited tumour growth. Both BMDC-based vaccines and vaccines based on DC lines had also an antimetastatic effect. These results indicate that the DC line-based vaccines, which represent a standard, well-characterized and more homogeneous material, technically easier to prepare than the fresh BMDC-based vaccines, can be utilized for therapy of surgical minimal residual disease in HPV 16-associated neoplasms and are prospective for relevant clinical trials.

Immunogenicity, immunosensitivity and cell surface adhesiveness of tumour vaccines carrying an inserted CD80 gene.

Cell surface adhesiveness, immunogenicity and immunosensitivity of tumour vaccines modified by the CD80 gene transfection was examined and compared to that of the parental MC12 murine sarcoma. Insertion of the CD80 gene substantially enhanced the adhesiveness of the genetically modified tumour cells to nylon wool non-adherent (T) but not to nylon wool adherent (B) lymphocytes. The increased adhesive interaction could be inhibited by anti-CD80 monoclonal antibody. CD80+ transfectants were more sensitive to the cytotolytic effect of MC12-immune splenocytes and IL-2-activated spleen cells than the parental MC12 sarcoma. Similarly, spleen cells from syngeneic mice immunized with CD80+ transfectants displayed a higher cytolytic activity when allowed to react with MC12 cells than splenocytes from mice immunized with the parental MC12 cells. These results suggest that a positive correlation exists among the expression of the CD80 molecules, T cell adhesion to the genetically modified cells, immunosensitivity of the CD80+ transfectants and the capacity of the transfectants to activate cytolytic, tumour-reactive effector cells in vivo. This correlation provides a rationale for gene therapy based on the construction of CD80- modified tumour vaccines.

Interleukin 2 gene therapy of residual disease in mice carrying tumours induced by HPV 16.

Experiments were designed to examine the efficacy of IL-2 gene therapy in a surgical minimal residual tumour disease, using moderately immunogenic MK16/1/IIIABC murine cells transformed by activated ras and HPV 16 E6/E7 oncogenes (MK16 cells). Previously we demonstrated that surgical minimal residual tumour disease (SMRTD) could be effectively cured when murine Mc12 sarcoma had been resected and the operated mice were treated with irradiated Mc12 sarcoma cells engineered to secrete IL-2. In this study we performed IL-2 gene therapy of MK16 carcinoma with two types of irradiated MK16-unrelated tumour cell vaccines. One type of vaccine was derived from MHC class I-matched Mc12 sarcoma cells engineered to secrete IL-2 and the other from MHC class I-discordant IL-2 producing plasmacytoma X63-m-IL-2. The vaccines did not share any tumour rejection antigen with the MK16 cells and served exclusively as a local source of IL-2 production. Both vaccines were capable of inhibiting MK16 tumours when administered peritumorally up to 15 days after MK16 tumour challenge. The irradiated MHC class I-matched and IL-2-producing Mc12 sarcoma vaccine was then selected for therapy of MK16 SMRTD. Whereas the recurrence rate in the operated MK16 carcinoma bearers was 80%, so that only 20% of mice were cured by surgery, approximately 65% of the MK16 carcinoma bearers were permanently protected when the surgery was followed by local administration of the IL-2-producing Mc12 sarcoma vaccine.

Genetically modified tumour vaccines.

Two genes, the gene coding for IL-2 and the gene encoding the CD80 molecule, were inserted into murine sarcoma MC12 cells. Tumorigenicity of a variety of cell clones with different expression of the inserted genes was assessed. Most of the genetically manipulated MC12 cell clones were less tumorigenic than the parental MC12 cell population. Tumorigenicity of the clones declined with increasing production of IL-2 as well as with the increasing expression of the CD80 molecule. When the tumorigenicity of the clones carrying an inserted IL-2 gene was compared with that of the clones carrying an inserted CD80 gene, it was found that the insertion of the IL-2 gene suppresses tumorigenicity more efficiently than insertion of the CD80 gene. Admixture of the IL-2-producing MC12 clones to the tumorigenic CD80(+) MC12 cell doses could completely inhibit the tumorigenicity of the CD80(+) cells. Insertion of the CD80 gene into sarcoma cells substantially enhanced the adhesive interaction between the MC12 sarcoma and syngeneic T lymphocytes.

CD80 and IL-2 signals cooperate in the regression of tumors transplanted in congenitally athymic mice.

Interleukin-2 and CD80 transfectants of a methylcholanthrene-induced murine sarcoma Mc12 (Mc12-IL-2 and Mc12-CD80 cells) with similar tumorigenicity in euthymic mice were utilized for experiments designed to investigate a co-stimulatory role of the CD80 molecule in allogeneic, congenitally athymic (nu/nu) mice. The CD80-transfected cells were as tumorigenic in nu/nu mice as the parental Mc12 sarcoma. The IL-2-transfected cells grew only transiently and regressed in all nu/nu recipients during four weeks after challenge with doses up to 5x10(7) cells. The 1:1 mixture of parental Mc12 with Mc12-CD80 cells grew progressively in all inoculated nu/nu mice; in a 1:1 mixture with parental Mc12 cells, Mc12-IL-2 cells were able to cause regressions in approximately 50% of nu/nu mice; the 1:1 mixture of Mc12-IL-2 and Mc12-CD80 transfectants showed only transient growth and regressed during four weeks in all inoculated nu/nu mice. Adoptive transfer of cell-mediated immunity revealed that spleen cells from tumor regressors were capable of transferring the resistance to Mc12 tumor in nu/nu mice. The spleen cells from tumor regressors were not cytolytic when allowed to react in vitro with Mc12, Mc12-IL-2, or Mc12-CD80 target cells. However, when grown in IL-2-containing medium, splenocytes from tumor regressors, but not the splenocytes from tumor progressors, could develop cytolytic activity directed against Mc12 target cells that was comparable to that of the splenocytes from tumor-free controls. These results suggest that the rejection of tumors in nu/nu mice was mediated by IL-2-dependent mechanisms in which the CD80 molecule played a co-stimulatory role; the results also indicate that the ability to be activated by IL-2 and to give rise to cytolytic activity of nu/nu splenocytes from tumor progressors is decreased.

Tumour inhibitory effects of plasmid DNA.

The experiments were designed to examine whether direct in vivo transfer of plasmid DNA not carrying any 'therapeutic' genes ('empty' plasmid DNA) can influence tumour growth. Murine MC-induced sarcoma Mc12 was transplanted i.m. in syngeneic recipients and the tumour-inoculated mice were treated either with repeated peritumoral (i.m.) injections of the naked plasmid DNA or with a single peritumoral (i.m.) injection of plasmid DNA incorporated in liposomes. Two plasmid DNA preparations, BCMGNeo and pON1 were utilized. The direct in vivo transfer of both 'empty' plasmid DNA preparations inhibited tumour growth and significantly prolonged survival of tumour-bearing mice. Our results emphasize the importance of plasmid DNA controls for evaluation of gene therapy of cancer based on the transfer of 'therapeutic' genes in tumour-bearing individuals.

Chemoimmunotherapy of cancer: potentiated effectiveness of granulocyte-macrophage colony-stimulating factor and ifosfamide derivative CBM-4A.

The effectiveness of combined chemoimmunotherapy with ifosfamide derivative CBM-4A and granulocyte-macrophage colony-stimulating factor (GM-CSF) was investigated in two experimental tumor models, 3MC-induced MHC class I+ sarcoma Mc12 and HPV16 E6/E7 oncogene-induced MHC class I- carcinoma MK16, transplanted in syngeneic mice. Treatment of Mc12 and MK16 tumor-bearing mice with GM-CSF or CBM-4A alone produced moderate anti-tumor effects. However, when the tumor-bearing mice were first treated i.p. with a single dose of CBM-4A (150 mg/kg) and three days later peritumorally with five daily doses of GM-CSF (100 ng/day), substantially stronger tumor-inhibitory effects were observed. The results indicate that in both, MHC class I+ and MHC class I- tumors, the combined chemoimmunotherapy can inhibit tumor progression more effectively than GM-CSF therapy or chemotherapy alone, and they suggest that GM-CSF should be considered as adjuvant to chemotherapy in clinical trials with HPV 16-associated neoplasms.

Age-related decrease in transplantability of human tumours in nu/nu mice.

Experiments were designed to assess age-related changes in the transplantability of human tumours xenografted in congenitally athymic (nu/nu) mice. It has been found that the number of progressively growing human tumour xenografts decreased significantly with increasing age of BALB/c nu/nu recipients. These findings, taken together with a previously recognized increase in the frequency of endogenous interleukin 2 (IL-2)-producing cells with age of nu/nu mice, prompted us to investigate whether administration of exogenous IL-2 to young adult nu/nu mice could change the transplantability of human tumours in the mice. Peritumoral administration of exogenous interleukin 2 to 8-week-old nu/nu mice inhibited the growth of the human tumour xenografts. In vitro activation of nu/nu splenocytes with exogenous Il-2 resulted in the generation of killer cells which have been found to be cytolytic when allowed to react with human tumour targets in 51Cr cytotoxicity assay. In addition, it has been found that the percentage of IL-2-activated Thy 1.2+ and ASGM1+ cells substantially increased with increasing age of nu/nu spleen cell donors. These findings are compatible with the hypothesis that the observed age-related decrease in takes of human tumour xenografts might be determined by the increasing level of IL-2 production and subsequent maturation of IL-2-dependent effector cells.

Gene therapy of cancer: use of IL-2 gene transfer and kinetics of local T and NK cell subsets.

Experiments were designed to compare the efficacy of recombinant IL-2 immunotherapy and IL-2 gene therapy of i.p. growing murine plasmacytoma X63-Ag8.653. The kinetics of peritoneal exudate mononuclear cells were monitored during the progression and gene therapy of the plasmacytoma, using cytofluorometric analysis and monoclonal antibodies against T and NK cell subsets. It has been found that the percentage of mice protected against plasmacytoma transplants was higher in mice treated by transfer of genetically manipulated IL-2-producing plasmacytoma cells as compared to the mice repeatedly injected with recombinant IL-2. Intraperitoneal inoculation of the X63-Ag8.653 plasmacytoma led in most of the inoculated mice to an increased percentage of NK+, ASGM1+, Thy 1.2+, CD3+ and TCR alpha beta+ cells in the peritoneal fluid. The presence of macroscopically detectable i.p. tumours was accompanied by a higher increase in the percentage of NK+ and TCR gamma delta+ cells. Local IL-2 gene therapy of the plasmacytoma either prevented or diminished an increase in the percentage of CD3+, Thy 1.2+ and TCR alpha beta+ lymphocytes.

Activation and phenotyping of LAK generated by exposure to product of cells transformed by interleukin 2 cDNA.

It has been previously found that local administration of X63-m-IL-2 cells transformed by interleukin 2 (IL-2) cDNA and constitutively producing large quantities of IL-2 mediated regressions of murine plasmacytomas and 3-methyl-cholanthrene-induced sarcomas transplanted in syngeneic mice. Here we show that killer cells generated by cultivation of spleen cells in supernatants from X63-m-IL-2 cultures (LAK) or by co-cultivation of murine splenocytes with X63-m-IL-2 cells were cytolytic for natural killer (NK)-sensitive as well as NK-resistant target cells, including the IL-2-producing X63-m-IL-2 cells. Spleen cells cultured in X63-m-IL-2 supernatants or co-cultivated with X63-m-IL-2 cells yielded predominantly Thy 1.2+, CD3+, LFA-1+ lymphocytes. The in vitro results suggest that the LAK cells generated due to the IL-2 production by genetically engineered cells probably help to terminate the treatment by killing the IL-2 producers.

Cell surface adhesiveness of mouse sarcoma lines evaluated by latex particle adherence assay: correlation with growth behavior and electrophoretic mobility.

Using the latex particle adherence assay and five mouse sarcoma cell lines of the identical origin, etiology and genotype but differing in malignancy we attempted to correlate the degree of cell surface adhesiveness with growth behavior and electrophoretic mobility of cells. Higher tumorigenicity of four of the cell lines (Mc11--Mc14) was associated with lower cell surface adhesiveness and, conversely, lower malignancy of the fifth line (Mc15) with higher cell surface adhesiveness. No simple correlation or causal relationship was found among the electrophoretic mobility of the lines and other cellular characteristics.