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J Zeuthen

Publications and source records attributed to J Zeuthen.

At least 73 records · Page 4Linked to original sources
PubMed1996

Clonal T cell responses in tumor infiltrating lymphocytes from both regressive and progressive regions of primary human malignant melanoma.

The T cell receptor (TCR) BV variable (V) gene repertoire of tumor infiltrating lymphocytes (TIL) found in progressive and regressive regions of the same primary human melanomas were characterized by reverse transcription coupled polymerase chain reaction (RT-PCR). After surgery, the tumors were divided into different parts which were judged as regressive or progressive regions by visual inspection. Subsequently this diagnosis was confirmed by histology. From a total of four primary melanomas analyzed, 2 were drawn to be HLA-A2+. Only relatively few BV-gene families were expressed at significant levels in each of the samples. Comparison of the BV-expression in regressive versus progressive regions of the same tumor revealed major differences in all cases examined. Direct sequencing of RT-PCR products indicated that highly expressed BV-gene families were of clonal origin in both the regressive and progressive regions. Together, these data strongly suggest the occurrence of clonal T cell responses in both regressive and progressive areas of the same primary tumor. The differences in expression of certain BV-genes may correlate with the functional activity of certain populations of tumor-infiltrating T cells.

Amino Acid Sequence↗
PubMed1996

Differential modulation by interferon gamma of the sensitivity of human melanoma cells to cytolytic T cell clones that recognize differentiation or progression antigens.

Human melanoma is a highly immunogenic tumor capable of inducing a specific immune response. A number of melanoma-associated antigens have been characterized during the past several years and can be classified into two groups: differentiation antigens-present also in normal melanocytes-and tumor-specific antigens, which, with the exception of testis, are present only in tumor cells. In a previous publication [Kirkin A. F., Petersen T. R., Olsen A. C., Li L., thor Straten P., Zeuthen J. (1995) Cancer Immunol Immunother 41:71] we have described the production of clones of cytotoxic T lymphocytes (CTL) against the highly immunogenic human melanoma cell line FM3. Using these clones we have defined four previously unknown melanoma-associated antigens, which could be subdivided into differentiation and progression antigens. In the experiments reported in this paper, we have further compared CTL clones from different groups and shown that the sensitivity of melanoma cells to CTL that recognize differentiation or progression antigens is differentially modulated during tumor progression as well as by the lymphokines interferon gamma (IFN gamma) and interleukin-10 (IL-10). The interaction of CTL clones recognizing progression antigens was strongly increased after treatment of melanoma cells with IFN gamma, while the recognition by CTL clones specific for differentiation antigens either was unchanged or significantly decreased. IL-10 treatment of melanoma cells induced up-regulation with respect to recognition by CTL clones specific for differentiation antigens without affecting the recognition of melanoma cells by CTL clones specific for progression antigens. Using cellular systems at different stages of tumor progression, we demonstrated that the progressed state of melanoma cells is associated with increased sensitivity to recognition by CTL clones detecting progression antigens, and with decreased sensitivity to CTL clones recognizing differentiation antigens. Mimicking tumor progression, treatment with IFN-gamma induced apparent down-regulation of differentiation antigens. A hypothesis is suggested in which IFN-gamma plays different roles in the immune response against poorly immunogenic and highly immunogenic melanoma cells, increasing the progression of poorly immunogenic tumor cells or promoting a strong immune response and regression of highly immunogenic melanoma cells.

Animals↗
PubMed1996

Cytotoxicity and proliferation of splenocytes and lymph node cells from adjuvant-treated nude mice. Studies of natural and in vitro activation.

The cytotoxicity of NK cells and lymphocytes derived from nonadherent splenocytes (SPL) and regional lymph node cells (LNC) from complete Freund's adjuvant (CFA)-treated athymic nude young (4-6 weeks) and aged (over 1 year) BALB/c nu/nu mice in vitro activated with rIL-2, anti-CD3 mAb or PPD was analyzed and compared to SPL and LNC from age-matched euthymic BALB/c mice. The high natural cytotoxicity to YAC-1 target cells of SPL or LNC could be augmented by 48 h stimulation in vitro with rIL-2, especially when derived from young nude BALB/c mice. The increase in cytotoxic activity was accompanied by increased proliferative activity of both SPL and LNC, which showed statistically significant differences between the rates of stimulation of cells from the young and aged groups. Anti-CD3 mAb strongly activated the cytotoxicity of BALB/c euthymic donor effector cells against P-815 target cells, corresponding to a very high proliferative activity of these cells, but anti-CD3 mAb did not lead to activation of effector cells from nude donors. FACS analyses of antigenic markers similarly showed an increased number of T cells in LNC from aged BALB/c nude donors, which, however, never reached the levels of those of euthymic animals.

Aging↗
PubMed1996

Generation of human monoclonal antibodies against ganglioside antigens and their applications in the diagnosis and therapy of cancer.

Different approaches to generating human monoclonal antibodies (MAbs) against tumor-associated ganglioside antigens have been carried out in several laboratories. A specific goal addressed by our laboratory is to produce human MAbs to several ganglioside antigens of relevance as therapeutic targets, such as the GM2, GD2, GD3 and GM3 gangliosides in melanoma. In vitro immunization of human B lymphocytes from normal donors was performed using liposomes containing gangliosides as the immunizing antigen combined with either complete tetanus toxoid or a synthetic peptide corresponding to a T helper epitope to stimulate in vitro immunization. Specific human anti-ganglioside antibodies were obtained, indicating that the antibody response found in vitro was antigen-driven. To overcome the widely reported problems concerning stability of immunoglobulin production by the antibody-secreting cell lines, a method of positive selection using GM3-coated magnetic beads has been developed in order to rescue unstable clones. Development of new methods to reproducibly generate ganglioside-specific human MAbs will amplify the possibilities for diagnostic and therapeutic applications.

Antibodies, Monoclonal↗
PubMed1995

Interleukin-2 gene therapy of residual EL-4 leukaemia potentiates the effect of cyclophosphamide pretreatment.

Experiments were designed to investigate a possible therapeutic role of interleukin-2 (IL-2) gene transfer in the model of murine (EL-4) leukaemia pretreated with cyclophosphamide. It has been found that i.p. pretreatment of the leukaemic mice with cyclophosphamide, followed by i.v. administration of irradiated cells, genetically engineered to produce IL-2 and used as a source of the cytokine (IR-IL-2 cells), cured a substantial percentage of the leukaemic mice. Neither treatment with cyclophosphamide nor administration of the IR-IL-2 cells alone had any significant therapeutic effect. Labelling of the EL-4 and IR-IL-2 cells with different fluorescent cell linkers followed by i.v. injection and detection of the labelled cells in cryostat sections of various organs has shown that both cell populations can be detected almost exclusively in the red pulp of the spleen, close to the white pulp nodules, thus providing the possibility of short-range local interactions among the IL-2-producing cells, IL-2-responsive defence effector cells and EL-4 leukaemia targets.

Animals↗
PubMed1995

Generation of human-melanoma-specific T lymphocyte clones defining novel cytolytic targets with panels of newly established melanoma cell lines.

Melanoma is a cancer where the immune system is believed to play an important role in the control of malignant cell growth. To study the variability of the immune response in melanoma patients, we derived melanoma cell lines from several HLA-A2+ and HLA-A2- patients. The melanoma cell lines studied were designated FM3, FM6, FM9, FM28, FM37, FM45, FM55p, FM55M1 and FM55M2 and were established from eight metastatic tumors as well as from one primary tumor from a total of seven different patients. On the basis of the ability of tumor cells to induce specific cytotoxic T lymphocytes (CTL) from peripheral blood lymphocytes (PBL) in mixed lymphocyte/tumor culture with HLA-A2+ melanoma cells, the FM3 cell line was characterized as highly immunogenic. To investigate the expression of different melanoma-associated antigens recognized by CTL on different melanoma cell lines, we selected the cell line FM3 for restimulation and further T cell cloning experiments. The lytic activity of CTL clones with good proliferative activity was examined using a panel of HLA-A2+ and HLA-A2- melanoma cell lines. None of the tested HLA-A2- melanoma cell lines were susceptible to lysis by the CTL clones, whereas allogeneic HLA-A2+ melanoma cell lines were lysed only by a few CTL clones. On the basis of their reactivity with different melanoma cell lines, it was possible to divide the present CTL clones into at least four groups suggesting the recognition of at least four different antigens. Three of these target structures probably are different from already-described HLA-A2-restricted melanoma-associated antigens, because their expression in the different melanoma cell lines do not correlate with the recognition of melanoma cells by these CTL. The results first indicate that poorly immunogenic melanoma cells may express melanoma-associated antigens, and also suggest that, by using CTL clones obtained against different HLA-class-I-matched melanoma cells, it is possible to define such antigens.

Antigens, Neoplasm↗
PubMed1995

T cell-independent B cell response to self-monosialogangliosides: primary response monoclonal antibodies.

Purified GM1 and GM2 gangliosides incorporated into liposomes were injected subcutaneously in BALB/c mice every 3-4 days after pretreatment of the animals with low-dose cyclophosphamide. Serum samples were collected at different intervals and tests by ELISA for the presence of anti-ganglioside antibodies. Four doses (50 micrograms each) were sufficient to raise a measurable primary type of response to GM1, while nine doses were required to obtain measurable IgM antibody titers to GM2. Three monoclonal antibodies (MAbs) wer generated by fusing splenocytes with mouse myeloma cells. The specificity of MAbs was determined by ELISA and HPTLC-immunostaining using a panel of purified glycolipids. The MAb designated E1 showed a high degree of specificity because it reacted only with N-acetyl GM2. Monoclonal antibody A3 reacted predominantly with GM2 and GM1, but also reacted moderately with the GM3 ganglioside. The epitope recognized by this MAb is suggested to be the trisaccharide sequence GalNAc beta 1-4(NeuAc alpha 2-3)Gal. The third MAb (F6) reacted strongly with GM1 but a weak reactivity was also observed with GD1b as well as with asialo-GM1, indicating that the terminal tetrasaccharide Gal beta 1-3GalNAc beta 1-4(NeuAc alpha 2-3)Gal- structure is probably involved in antigenic recognition. Formalin-fixed and paraffin-embedded tissue sections were stained with the E1 and A3 MAbs, using the avidin-biotin complex (ABC) technique. Strong immunoreactivity for E1 appeared in the tumor cells of five primary lung carcinomas and in five malignant melanomas. No immunoreactivity was demonstrated in the parenchyma of a lung without malignancy, or in a metastasis from a colon carcinoma.

Animals↗
PubMed1995

A human melanoma cell line, recognized by both HLA class I and class II restricted T cells, is capable of initiating both primary and secondary immune responses.

We have characterized a melanoma cell line, FM3, established from a metastasis of a 75 year old female patient (HLA-A2, HLA-DQ7) with malignant melanoma. This cell line expresses both HLA class I and class II antigens, as well as several important accessory molecules at high levels. FM3 cells were shown to function as a stimulator of both allogeneic as well as autologous mixed lymphocyte tumour cell culture (MLTC). From these autologous MLTC we were able to generate cytotoxic T cell clones indicating that FM3 is capable of processing and presenting endogenous antigens. We have used this cell line in a model system to investigate whether these cells were able to initiate and support an immune response with specificity for selected peptide antigens. The FM3 cell line was capable of presenting a HLA-DQ7 restricted ras derived peptide (5-21, 13Gly- >Asp) to a previously established T cell clone, RM70. The ability of FM3 to function as an antigen presenting cell (APC) was comparable to that of an autologous Epstein Barr virus (EBV) transformed B cell line. The CD4+ T cell clone RM70 showed a peptide-specific anti-proliferative effect on FM3 cells. This growth inhibition was not due to cytotoxicity as measured in a standard 4 h chromium release assay. The FM3 cell line also presented a HLA-A2 restricted nonapeptide derived from the influenza matrix protein, M1(58-66) to a CD8+ T cell line specific for this peptide. This resulted in an effective killing of the melanoma cells. Together, these data suggest that some melanomas may initiate an immune response by presenting their own specific antigens in an immunogenic context, and subsequently serve as targets for T cells of both the CD4+ and CD8+ phenotype.

Aged↗
PubMed1995

Antigen-specific primary immune response of human B-lymphocytes after in vitro immunization with GM3 ganglioside.

In vitro immunization of human B-lymphocytes was performed with liposomes containing the monosialoganglioside GM3, with or without either complete tetanus toxoid or a synthetic T helper epitope derived from tetanus toxin (determinant 830-843). The immunized B-cells were Epstein-Barr virus transformed and the human anti-ganglioside antibody response was evaluated using an indirect ELISA against different mono- and disialogangliosides. Clones producing antigen-specific human antibodies of the IgM isotype against the ganglioside GM3 used as the immunogen were selected and one clone, IM-11, was further characterized. In addition, a method of positive selection using GM3-coated magnetic beads has been developed which allowed us to rescue unstable clones. The binding of the human antibody IM-11 to a large panel of glycosphingolipids separated on thin-layer plates was studied. The human MAb IM-11 was found to bind strongly to NeuAcGM3, IV3 NeuAcnLc4 and sulfate containing glycosphingolipids and weakly to NeuGcGM3. Immunohistological staining of melanoma and breast cancer biopsy sections showed a selective reactivity of IM-11 with tumor cells which varied among different tumors.

Amino Acid Sequence↗
PubMed1995

Analysis of T cell receptor alpha beta variability in tumor-infiltrating lymphocytes in primary and metastatic melanoma.

The T cell receptor (TCR) alpha beta variable (V) gene family usage of tumor-infiltrating lymphocytes (TIL) in different primary human malignant melanomas and corresponding metastatic lesions were characterized using a recently developed method using the reverse transcription coupled polymerase chain reaction (RT-PCR). This semiquantitative RT-PCR method could be adapted to analysis of formalin-fixed, paraffin-embedded histopathological samples of primary tumor material and demonstrated to be reproducible and to be useful for the assessment of V alpha- and V beta-gene family usage in tumor samples. The TIL in primary tumors were observed to preferentially express certain TCR V alpha- and V beta-gene families: V alpha 4, and V beta 8 were highly expressed in several of the primary tumors analyzed using this method. With respect to V alpha 22 and V beta 8, the preferential expression of these V-gene families was demonstrated to be due in situ clonal expansion of T cells by means of cloning and sequencing of the CDR3 regions (V-J or V-D-J, respectively) corresponding to the RT-PCR products from one of the primary tumors. The observed preferential usage of certain TCR V alpha and V beta-genes strongly suggest the in situ clonal expansion of specific populations of T cells in accordance with recent results from others. These clonal T cell populations probably react with certain melanoma-associated peptides presented by specific HLA molecules. The preferential usage of certain V alpha- and V beta-gene families observed in several tumors further supports the involvement of a limited number of shared melanocyte or melanoma-associated peptides. Since the HLA status of the patients is obviously important to interpret these results, some of the patients were typed for HLA-A1 and -A2, the two most well-characterized restriction elements for melanoma-associated antigens, either serologically or by a newly developed RT-PCR method which similarly could by applied directly to the tumor material. In TIL in primary melanomas, a possible correlation was suggested between HLA-A2 and the preferential usage of the TCR V-gene families V alpha 4, V alpha 5, V alpha 22 and V beta 8, whereas the V beta 3-gene family appeared to be expressed together with HLA-A1. The V-gene families which were highly expressed in the primary tumors were generally not, or only very weakly, expressed in the corresponding metastases and vice versa, possibly reflecting a substantial change in the phenotype of the metastatic melanoma target cells. Continued studies of larger patient materials will be necessary to extend and validate these conclusions and of obvious interest for the further analysis of the T cell response in melanoma.

Amino Acid Sequence↗
PubMed1994

Transfection of glioma cells with the neural-cell adhesion molecule NCAM: effect on glioma-cell invasion and growth in vivo.

The tumor growth and the invasive capacity of a rat glioma cell line (BT4Cn) were studied after transfection with the human transmembrane 140-kDa isoform of the neural-cell adhesion molecule, NCAM. After s.c. injection, the NCAM-transfected cells showed a slower growth rate than the parent cell line (BT4Cn). Upon intracerebral implantation with BT4Cn cells and different clones of NCAM-transfected cells, all animals developed neurological symptoms within 13-16 days. However, the tumors showed different growth characteristics. The NCAM-transfected BT4Cn cells were localized in the region of the injection site, with a sharply demarcated border between the tumor and brain tissue. In contrast, the parental cell line showed single-cell infiltration and more pronounced destruction of normal brain tissue. Using a 51Cr-release assay, spleen cells from rats transplanted with BT4Cn tumor cells generally showed a lower cytotoxic response than the spleen cells from rats transplanted with the transfected variants of BT4Cn cells, indicating that the transfection procedure in itself mediated an activation of the immune system. The present data suggest that NCAM may influence the malignant behavior of rat glioma cells in vivo.

Animals↗
PubMed1994

Blood group ABO-related glycosylation of urothelial cell lines: immunocytological, enzymatic, and genetic characterization.

Three immortalized, human urothelial cell lines were characterized with respect to their ABO-related carbohydrate phenotypes using a panel of monoclonal antibodies directed to a series of carbohydrate epitopes (Lac, sialylated Lac, Le(a), sialylated Le(a), Le(x), sialylated Le(x), H types I and II, Ley, Leb, A monofucosylated types I and II, ALey, Aleb, and A type III). The glycosyltransferases forming some of these epitopes (beta 1-3/4 galactosyltransferase, alpha 1-2 fucosyltransferase, alpha 1-3 galactosyltransferase, and alpha 1-3-N-acetyl-galactosaminyltransferase) were determined by enzyme assays. The ABO gene complex was analyzed by Southern blotting, Northern blotting, and polymerase chain reaction across the O deletion and across base differences between the A and B alleles. The immunocytochemical stainings showed marked differences between the three cell lines; the high grade (tumorigenic, metastatic) cell line showed difucosylated types I and II structures, and the low grade (nontumorigenic, nonmetastatic) cell lines showed monofucosylated types I and II structures. Polymerase chain reaction genotyping of the cell lines indicated that one was OO, one was AA, and one was A plus a mutated allele. Northern blotting showed RNA encoding the A transferase. However, even though both of the A cell lines seemed to have an intact gene, which could produce A transferase and transcribed RNA, none of them showed any activity of the A gene encoded enzyme or any A-structures at the cell surface. In contrast, the three other examined glycosyltransferases were active. The three urothelial cell lines reflect in vivo findings in humans. They represent a competent system for in vitro studies of the different carbohydrate transferase genes responsible for the carbohydrate structures expressed on the cell surface in bladder tumors.

ABO Blood-Group System↗
PubMed1994

Preferential usage of T-cell receptor alpha beta variable regions among tumor-infiltrating lymphocytes in primary human malignant melanomas.

The usage of T-cell-receptor (TCR) alpha beta variable (V) regions among tumor infiltrating lymphocytes (TILs) in primary human malignant melanomas was characterized using a method based on the polymerase chain reaction (PCR). A panel of 57 different variable-region primers specific for the TCR V alpha I-29 and V beta I-28 was designed, and a semi-quantitative PCR method applicable to formalin-fixed, paraffin-embedded tissues was developed. This semi-quantitative method was demonstrated to be reproducible and to be useful for the assessment of V alpha- and V beta-gene-family usage in formalin-fixed, paraffin-embedded tissue samples. A total of 9 different histopathologically characterized primary tumors were analyzed in this study. The TILs in these tumors were found to preferentially express certain TCR V alpha and V beta regions. The differential usage of certain V alpha regions was very pronounced as illustrated by V alpha 4, which was highly expressed in 3/8 tumors, and V alpha 22, which was highly expressed in 4/8 tumors. For comparison, specific highly expressed V alpha regions in control samples of peripheral-blood lymphocytes rarely exceeded 10%. The most highly expressed V beta region was V beta 8, which was highly expressed in 2/8 tumors. For the highly expressed V alpha 4 and V alpha 22 and V beta 8 regions, the high levels may be explained by the in situ clonal or oligoclonal expansion of TIL. In one specific case, the high expression of V beta 8 was due to expansion of a single clone of TILs, as evidenced by a fully readable sequence of the CDR3 (V-D-J) region, determined by direct sequencing of the PCR product corresponding to V beta 8. In contrast, sequence analysis of V alpha 22, which was expressed in the same tumor sample at similar levels, demonstrated the simultaneous presence of 3 different CDR3 (V-J) sequences derived from V alpha 22 transcripts of exactly the same length. The observed preferential use of TCR V alpha and V beta regions suggests the in situ clonal expansion of specific populations of T-cells, possibly reactive with melanoma-associated peptides presented by HLA molecules. The preferential use of TCR V alpha and V beta regions may imply the involvement of a limited number of shared melanoma-associated peptides.

Base Sequence↗
PubMed1994

Analysis of T cell receptor alpha beta variability in lymphocytes infiltrating melanoma primary tumours and metastatic lesions.

The T cell receptor (TCR) alpha beta variable (V) gene family usage of tumour-infiltrating lymphocytes (TIL) in four different primary human malignant melanomas and their corresponding metastatic lesions was characterized using a recently developed method based on the reverse-transcription-coupled polymerase chain reaction (RT-PCR). All patients were typed for HLA-A1 and -A2, either serologically or by a newly developed RT-PCR method. Two of these patients expressed HLA-A2, one the HLA-A1 haplotype and one further patient was heterozygous HLA-A1/-A2. The prognostic parameters for all four patients indicated that rapid progression of the disease was to be expected. However, only two of the patients showed rapid progression, while the remaining two patients are still alive after more than 3 years. In TIL in primary melanomas, a possible correlation was suggested between HLA-A2 and the preferential usage of the TCR V gene families V alpha 4, V alpha 5, V alpha 22 and V beta 8, whereas the V beta 3 gene family appeared to be expressed together with HLA-A1. Other highly expressed V gene families, apparently not restricted to either HLA-A1 or -A2, were V alpha 1 (expressed in three of four primary tumours) and V alpha 21 (expressed in two of four tumours). We found no evidence suggesting any correlations between the haplotypes HLA-A1 and -A2 and preferential V gene family expression in the metastatic lesions, and the only common feature was V alpha 8, which was found to be highly expressed in two out of three subcutaneous metastases. The V gene families, which were highly expressed in the primary tumour were generally not, or only very weakly, expressed in metastases and vice versa, possibly reflecting a change in the phenotype of the metastatic melanoma target cells. With regards to patient 0368, it was possible to obtain and study material from two subcutaneous metastases. The first metastasis was excised more than a year after the primary tumour, showing a completely different V region repertoire. The second metastasis was excised at surgery 2 years after primary surgery and likewise showed a dramatic shift in comparison to the first subcutaneous metastasis. Although the present study only included a small number of patients, it suggests that the estimation of V gene expression, if applied to a larger amount of patient material, might make it possible to substantiate further the suggested correlations between the T cell response against the tumour, HLA and antigen expression.(ABSTRACT TRUNCATED AT 400 WORDS)

Aged↗
PubMed1994

Strain- and age-dependent natural and activated in vitro cytotoxicity in athymic nude mice.

The defect in athymic nude mice with respect to T-lymphocyte number and function is accompanied by increased levels of natural cytotoxicity as well as other immune reactions with potential antitumor effects. With increasing age of immunodeficient mice the take rate of xenotransplanted tumors decreases while the number of cells with T-lymphocyte markers increases and some T-lymphocyte-associated functions become detectable. In the present study the natural cytotoxicity of nonadherent splenocytes from young (4-6 weeks) and aged (about 1 year) BALB/c nu/nu mice was analyzed and compared with that of splenocytes from normal euthymic young and old Balb/c mice on the one hand, and with Bar nu/nu and NCr nu/nu young and old mice on the other. To investigate a possible contribution of T lymphocytes to the cytotoxic effect in athymic mice, LAK cells were generated. For this purpose, the nonadherent splenocytes were exposed in vitro either to IL-2 or to anti-CD3 mAb, specifically to activate T lymphocytes expressing TcR-CD3 in the latter case. Cytotoxic in vitro assays were applied using YAC-1 (NK-sensitive) and P-815 (NK-resistant, LAK-sensitive) target cells in parallel experiments in which splenocytes from young and old donors were used as effector cells. Splenocytes from young immunodeficient mice showed consistently high cytotoxicity with YAC-1 cells. In aged athymic mice, splenocytes stimulated in vitro with anti-CD3 mAb showed cytotoxicity to P-815 (LAK-sensitive) cells. FACS analyses of antigenic markers revealed an increased number of T cells in spleens of aged immunodeficient mice, with differences between mice of the examined strains and a decrease in the number of NK cells in aged mice.

Aging↗
PubMed1994

Gene therapy of plasmacytoma: comparison of the therapeutic efficacy of tumour cells transduced with the interleukin-2, interleukin-4, or interleukin-6 genes.

The present study was designed to compare the tumour inhibitory effects of local therapy based on insertion of cloned IL-2, IL-4, or IL-6 genes into the genome of murine plasmacytoma X63-Ag8.653, followed by injection of the genetically modified cells to the vicinity of the parental plasmacytoma growing in syngeneic mice. It was also designed to investigate the effects of combined gene therapy with IL-2- and IL-6-producing plasmacytoma cells. It has been found that insertion of the IL-2 gene into the genome of X63-Ag8.653 cells can abrogate tumorigenicity of the transduced cells more effectively than insertion of the IL-4 or IL-6 gene. Peritumoral administration of the genetically modified plasmacytoma cells producing IL-6 (X63-h-IL-6) resulted in a therapeutic effect comparable with that of the IL-2-producing cells (X63-m-IL-2), whereas no substantial therapeutic effect of IL-4-producing cells (X63-m-IL4) was observed. The combined gene therapy with IL-2- and IL-6-producing cells did not give any additive or potentiated therapeutic effect.

Animals↗