To examine the self-association of CD4 molecules and preliminary studies on its biological function by several indirect methods. A series of CD4 chimeras were generated including truncated CD4 lacking the short cytoplasmic tail, deleted mutantsD1/D2 devoid of D3 and D4 and D3/D4 devoid of D1 and D2 by PCR techniques, as well as another three CD4 chimeric genes by fused human Fas cytoplasmic death domain to the downstream of the above chimeras respectively. All these molecules were subcloned into pEGFP-N1, forming the corresponding expression vectors. After introducing into HEK293 cells, gene-modified cell morphological changes and target protein subcellular localization were observed and analyzed by a confocal microscopy. Moreover, stable 293/CD4 clones were obtained by transfecting the truncated CD4 recombinant plasmid into the HEK293 cell line and selected by G418. The fluorescene intensity and rosette formation of different clones was each analyzed by a confocal microscopy and cell adhesive assays. It's seen that CD4-Fas fusion gene could induce approximately 80% cell apoptosis of transfected HEK293 cells, compared to FKBP12-Fas is about 30% and CD4 gene only is 7%. Furthermore, both D1/D2-Fas and D3/D4 Fas chimeras could trigger nearly all transfected HEK293 cells to death. Cell adhesion assays showed that neither the D1/D2 nor D3/D4 chimeras when expression in HEK293 cells binds to MHC class II + Raji B cells. Interestedly, there were two type stable clones among 293/CD4. Fluorescence intensity analysis displayed that one' mean fluorescence intensity value is about twice of the other while cell-cell binding examination showed that the former is capable of forming rosette with Raji cells but the latter. All these results suggest that CD4 molecules most likely could exist as a dimer or even an oligomer on transfected HEK293 cell surface, which constitute a functional form for stable binding to MHC class II molecules.
Antigen-Presenting Cells ; immunology ; metabolism ; CD4 Antigens ; chemistry ; genetics ; metabolism ; CD4-Positive T-Lymphocytes ; immunology ; metabolism ; Cell Line ; Dimerization ; Fas Ligand Protein ; metabolism ; Histocompatibility Antigens Class II ; genetics ; immunology ; metabolism ; Humans ; Mutagenesis, Site-Directed ; Protein Binding ; genetics ; Protein Multimerization

Animals ; Antigens, Differentiation, B-Lymphocyte ; immunology ; Gene Expression ; Hepacivirus ; immunology ; Histocompatibility Antigens Class II ; immunology ; Mice ; Mice, Inbred BALB C ; Th1 Cells ; immunology ; metabolism ; Viral Hepatitis Vaccines ; genetics ; immunology

OBJECTIVETo construct a dendritic cell vaccine transduced by murine alpha-fetoprotein (mAFP) gene, and evaluate its immunoprotective effect on C57BL/6J mice during the induction of hepatocellular carcinoma by diethylnitrosamines, carbon tetrachloride and ethanol.

METHODSDendritic cells (DCs) were induced and augmented by murine IL-4 and GM-CSF, and transfected by recombinant adenovirus engineered with mAFP gene. Major MHC class I and II, B7.1 (CD80), B7.2 (CD86), CD18a, and CD54 molecules on DC were analyzed by FACS. 80 C57BL/6J male mice were randomly divided into 4 groups (20 mice per group): Simple DC inoculated group, pAdBM5-mAFP-DC inoculated group, pAdBM5-mAFP plasmid inoculated group, and PBS control group. They were immunized once with 5 x 10(5) DCs (0.1 ml)/mouse administered s. c. in the left flank or 100 mg pAdBMS-mAFP plasmid/mouse administered i. m. in the left tibialis anterior muscle. Inoculation was conducted once a week for 4 weeks after 3 times consecutive immunization initially. At the same time of immunization, DEN/CCl4/ethanol were given to induce hepatocellular carcinoma. Tumor incidence was assessed after 20 weeks.

RESULTSA transgenic DC vaccine was successfully constructed and the mAFP transgenic DCs expressed high level molecules of major MHC class I and II , B7.1, B7.2, CD18a, and CD54. After the 20-week induction, the incidence of primary hepatocellular carcinoma (PLC) was 70.0% in simple DC inoculated group, 25.0% in pAdBMS-mAFP-DC inoculated group, 65.0% in pAdBM5-mAFP plasmid inoculated group, and 75.0% in PBS control group. There was a significant difference between group B and other groups (P < 0.05).

CONCLUSIONmAFP transgenic DC tumor vaccine inoculation may induce strong immunoprotection against liver carcinogenesis and tumor development and reduce PLC incidence induced by DEN/CCl4/ethanol.

Adenoviridae ; genetics ; Animals ; B7-1 Antigen ; metabolism ; Cancer Vaccines ; Carbon Tetrachloride ; Cells, Cultured ; Dendritic Cells ; cytology ; immunology ; metabolism ; Diethylnitrosamine ; Ethanol ; Genetic Vectors ; Histocompatibility Antigens Class I ; metabolism ; Histocompatibility Antigens Class II ; metabolism ; Intercellular Adhesion Molecule-1 ; metabolism ; Liver Neoplasms, Experimental ; chemically induced ; immunology ; prevention & control ; Male ; Mice ; Mice, Inbred C57BL ; Random Allocation ; Recombinant Proteins ; genetics ; metabolism ; Transfection ; alpha-Fetoproteins ; genetics ; metabolism

We examined the effect of class II transactivator (CIITA) down-modulation on allograft rejection. To inhibit the function of CIITA, we constructed a series of CIITA mutants and found one exhibiting the dominant-negative effect on the regulation of major histocompatibility complex (MHC) class II expression. To test whether the CIITA dominant-negative mutant reduces immunogenecity, CIITA-transfected melanoma cells were injected into allogeneic host and assessed for immune evading activity against host immune cells. We demonstrated that the CIITA dominant-negative mutant allowed tumor nodules to develop earlier in the lung than control by this tumor challenge study. Furthermore, skin grafts deficient for CIITA also survived longer than wild-type in allogeneic hosts. Both the tumor challenge and skin graft studies suggest the inhibition of CIITA molecules in donor tissue would be beneficial to the control of allo-response.
Transplantation, Homologous ; Transfection ; Trans-Activators/genetics/*immunology/metabolism ; Trans-Activation (Genetics)/genetics/immunology ; Skin Transplantation ; Nuclear Proteins/genetics/*immunology/metabolism ; Mutation ; Mice, Transgenic ; Mice, Knockout ; Mice, Inbred C57BL ; Mice, Inbred BALB C ; Mice ; Melanoma, Experimental/genetics/immunology/pathology ; Male ; Interferon Type II/pharmacology ; Humans ; Histocompatibility Antigens Class II/genetics/*immunology/metabolism ; Graft Survival/genetics/immunology ; Graft Rejection/genetics/*immunology ; Genes, MHC Class II/genetics/immunology ; Flow Cytometry ; DNA, Complementary/genetics ; Cell Proliferation/drug effects ; Cell Line, Tumor ; Animals

OBJECTIVETo investigate whether there is an association between the expression of B7-H1 in HBV transgenic mice and the immune tolerance to HBV.

METHODST cells stimulatory capacity of DC was analyzed using mixed lymphocyte reaction. Expression of MHC-II, CD80, CD86, B7-H1 on DC was detected by Flow Cytometry. IL-2, IFNgamma, IL-10 production of T cells were determined by using ELISA. B7-H1 mRNA and protein expression in liver tissue were detected by RT-PCR and Western blotting respectively.

RESULTSThe ability of DC cells from HBV transgenic mice to stimulate T cell proliferation was significantly impaired compared with DC cells from control mice (t = 16.674, 19.674, 21.712, P less than 0.01). Expression of MHC-II, CD80 on DC was markedly decreased in transgenic mice (t = 7.910, 6.413, P less than 0.05). Meanwhile, the expression of CD86 and B7-H1 on DC cells in HBV transgenic mice were not significantly different from that in control mice. The levels of IL-2, IFNgamma, IL-10 in supernatant of T cells was significantly lower compared with controls (t = 18.712, 18.712 and 11.683, P less than 0.05). There was no significant difference in B7-H1 expression at mRNA and protein levels in liver tissue compared with controls.

CONCLUSIONSFunctional defect of DC, partly due to decreased expression of MHC-II, CD80, but not related to B7-H1 expression, is the cause for immune tolerance to HBV in HBV transgenic mice.

Animals ; Antigens, CD ; biosynthesis ; genetics ; Cell Proliferation ; Cytokines ; biosynthesis ; Dendritic Cells ; immunology ; metabolism ; Flow Cytometry ; Hepatitis B virus ; genetics ; immunology ; Histocompatibility Antigens Class II ; metabolism ; Immune Tolerance ; Liver ; metabolism ; Mice ; Mice, Inbred BALB C ; Mice, Inbred C57BL ; Mice, Transgenic ; RNA, Messenger ; genetics ; metabolism ; Spleen ; immunology ; metabolism ; T-Lymphocytes ; immunology ; metabolism

OBJECTIVETo investigate if granulocyte-macrophage colony stimulating factor (GM-CSF) gene-modified dendritic cells (DC) enhance antitumor immunity in vitro.

METHODSMice were injected with chemokine ligand 3 (CCL3) via the tail vein. Fresh B220(-)CD11c(+) cells were sorted from the peripheral blood mononuclear cells (PBMCs) and cultured into DCs by cytokines.DCs were transfected with AdGM-CSF gene at different ratios of multiplicity of infection (MOI) to determine the optimal gene transfection conditions, and the expression of GM-CSF was detected after transfection. The variation of GM-CSF gene-modifiedDCs were analyzed by morphological examination, phenotype analysis, and mixed lymphocyte reaction (MLR).DCs were loaded with gastric cancer antigen obtained by freezing and thawing method. The killing effect of DCs vaccine-stimulated T lymphocytes on gastric cancer cells was assessed by MTT assay. INF-gamma production was determined with the INF-gamma ELISA kit.

RESULTSB220(-)CD11c(+) cells increased obviously after CCL3 injection. The ELISA results showed that after GM-CSF gene modification, DCs could produce high level of GM-CSF. When DCs were transfected with AdGM-CSF gene at MOI equal to 100, the GM-CSF level in culture supernatants reached saturation [(130.00 +/- 12.61) pg/ml]. After GM-CSF gene-modification, DCs tend to be more maturated as detected by morphological observation and phenotype analysis. At the same time, the capacity of activating the proliferation of allogeneic T lymphocytes was enhanced greatly. T lymphocytes stimulated by DCs transfected with GM-CSF gene showed a specific killing effect on gastric carcinoma cells and produced high level of INF-gamma [(1245.00 +/- 13.75) pg/ml].

CONCLUSIONAfter GM-CSF gene modification, DCs can produce high level of GM-CSF, which tend to be more maturated, and the capacity of activating the proliferation of allogeneic T lymphocytes is enhanced greatly. GM-CSF gene modified DCs can induce specific CTL to target tumor cells in vitro.

Adenoviridae ; genetics ; Animals ; B7-1 Antigen ; metabolism ; B7-2 Antigen ; metabolism ; CD40 Antigens ; metabolism ; Cancer Vaccines ; immunology ; Cell Line, Tumor ; Cell Proliferation ; Cytotoxicity, Immunologic ; Dendritic Cells ; cytology ; immunology ; metabolism ; Female ; Granulocyte-Macrophage Colony-Stimulating Factor ; genetics ; metabolism ; Histocompatibility Antigens Class II ; metabolism ; Interferon-gamma ; secretion ; Mice ; Mice, Inbred BALB C ; Recombinant Proteins ; Stomach Neoplasms ; immunology ; metabolism ; pathology ; T-Lymphocytes, Cytotoxic ; cytology ; immunology ; Transfection

Analysis of the T-cell receptor (TCR) repertoire of innate CD4+ T cells selected by major histocompatibility complex (MHC) class II-dependent thymocyte-thymocyte (T-T) interaction (T-T CD4+ T cells) is essential for predicting the characteristics of the antigens that bind to these T cells and for distinguishing T-T CD4+ T cells from other types of innate T cells. Using the TCRmini Tg mouse model, we show that the repertoire of TCRalpha chains in T-T CD4+ T cells was extremely diverse, in contrast to the repertoires previously described for other types of innate T cells. The TCRalpha chain sequences significantly overlapped between T-T CD4+ T cells and conventional CD4+ T cells in the thymus and spleen. However, the diversity of the TCRalpha repertoire of T-T CD4+ T cells seemed to be restricted compared with that of conventional CD4+ T cells. Interestingly, the frequency of the parental OT-II TCRalpha chains was significantly reduced in the process of T-T interaction. This diverse and shifted repertoire in T-T CD4+ T cells has biological relevance in terms of defense against diverse pathogens and a possible regulatory role during peripheral T-T interaction.
Amino Acid Sequence ; Animals ; Antigens, Surface/metabolism ; CD4-Positive T-Lymphocytes/cytology/*immunology/*metabolism ; Cell Communication ; Cell Differentiation/genetics/immunology ; Clonal Evolution ; Histocompatibility Antigens Class II/*immunology ; *Immunity, Innate ; Immunophenotyping ; Lymphocyte Count ; Mice ; Mice, Knockout ; Mice, Transgenic ; Peptide Fragments/chemistry ; Phenotype ; Receptors, Antigen, T-Cell/chemistry/*genetics/metabolism ; Receptors, Antigen, T-Cell, alpha-beta/chemistry/genetics ; Spleen/cytology ; Thymocytes/cytology/immunology/metabolism

CD40 ligand (CD40L) expressed by activated CD4+ T cells is a family member of membrane bound TNF family ligand and its interaction with CD40 expressed in APC has been shown to contribute in enhancing immune response. Exogenous stimulation through CD40 has been performed using soluble trimeric CD40L, anti-CD40 monoclonal antibody and cells expressing CD40L. Schneider 2 (S2) cells, a cell line derived from Drosophila melanogaster, was transfected with a plasmid vector, pAc5.1/V5-HisA, for the constitutive expression of CD40L (S2-CD40L). Upon incubation of S2-CD40L with B-lymphocytes for 6 days, activated B cells were examined by counting B cell numbers and for activation markers including CD86 and HLA Class II molecules. The activated B cells were tested for its efficient APC function by mixed lymphocyte reactions (MLR) and enzyme-linked Immunospot (ELISPOT) assay. S2-CD40L was cultured for a year and maintained CD40L expression (>90%). S2-CD40L induced B cell activation as demonstrated by increment of total B cells and up-regulation of CD86 and MHC Class II molecules. Activated B cells pulsed with peptide from human cytomegalovirus pp65 antigen efficiently induced both proliferation and IFN-gamma secretion of T cells. Our result suggests that S2-CD40L can efficiently and conveniently generate B cells as a functional APC and represents a potential role for B-cell mediated cancer immunotherapy.
Animals ; Antigen Presentation/*immunology ; Antigens, CD86/metabolism ; B-Lymphocytes/cytology/*immunology/metabolism ; CD4-Positive T-Lymphocytes/immunology ; CD40 Ligand/genetics/*metabolism ; Cell Line ; Cell Proliferation ; Coculture Techniques ; Drosophila melanogaster ; Gene Expression ; Histocompatibility Antigens Class II/metabolism ; Humans ; *Lymphocyte Activation ; Research Support, Non-U.S. Gov't ; Transfection

Receptor activator of NFkappaB ligand (RANKL) is known as a key regulator of osteoclastogenesis. However, the fact that fibroblasts and periodontal ligament cells express RANKL in response to bacterial substances, suggests that RANKL may have evolved as a part of the immunity to infection. As RANKL increases the survival and activity of dendritic cells, it may have similar effects on macrophages. To address this issue, we studied the effect of RANKL on various functions of macrophages using mouse bone marrow derived macrophages. RANKL enhanced the survival of macrophages and up-regulated the expression of CD86. RANKL-treated macrophages showed increased allogeneic T cell activation and phagocytic activity compared to control cells. In addition, RANKL increased the expression of TNFalpha, MCP-1, and IL-6 but not of IL-10, IL-12, IFN-gamma, and iNOS. Collectively, RANKL augmented the activity of macrophages especially as antigen presenting cells, suggesting its new role in immune regulation.
Animals ; Antigen-Presenting Cells/cytology/*drug effects/immunology/*metabolism ; Antigens, CD86/metabolism ; Carrier Proteins/*pharmacology ; Cell Death/drug effects ; Cell Survival/drug effects ; Cells, Cultured ; Cytokines/metabolism ; Flow Cytometry ; Histocompatibility Antigens Class II/metabolism ; Inflammation Mediators ; Interferon Type II/pharmacology ; Lipopolysaccharides/pharmacology ; Macrophages/cytology/*drug effects/immunology/*metabolism ; Membrane Glycoproteins/*pharmacology ; Mice ; Mice, Inbred C57BL ; Mice, Inbred ICR ; Nitric Oxide Synthase Type II/metabolism ; Phagocytosis/drug effects ; Research Support, Non-U.S. Gov't ; T-Lymphocytes/immunology/metabolism ; Up-Regulation/drug effects/genetics

BACKGROUNDGenetic modification of dendritic cells (DCs) has been used as an effective approach to enhance anti-tumor immunity. RNA interference (RNAi), which can cause the degradation of any RNA in a sequence-specific manner, is a post-transcriptional gene silencing mechanism. In this study, small-interfering RNA (siRNA) specific for the Ii gene was transfected into DCs, and the anti-tumor immunity of Ii-silenced DCs was assessed.

METHODSThe silencing effect of siRNA was evaluated by Western blotting and real-time PCR analyses. In vitro cytotoxic activity of T cells was evaluated using a Cytotox 96(®) non-radioactive cytotoxicity assay kit. The time to tumor onset and the tumor volumes were used as reliable indices to assess the anti-tumor immunity in vivo. To further examine the mechanisms underlying the anti-tumor immunity, flow cytometry analysis was used.

RESULTSThe Ii expression of DCs was significantly reduced after Ii siRNA transfection. Significant in vitro anti-tumor ability was exhibited when DCs were co-transfected with Ii siRNA plus endogenous tumor antigen (P < 0.05). Furthermore, tumor growth was greatly inhibited when mice were immunized with DCs transfected with Ii siRNA plus tumor antigen prior to or subsequent to tumor implantation. Flow cytometry analysis in vitro and in vivo indicated that both CD4(+) and CD8(+) T cells were significantly activated in the Ii siRNA group (P < 0.05).

CONCLUSIONSilencing of the Ii gene of DCs may offer a potential approach to enhance DC-based anti-tumor immunity.

Animals ; Antigens, Differentiation, B-Lymphocyte ; genetics ; metabolism ; Blotting, Western ; Cells, Cultured ; Dendritic Cells ; immunology ; metabolism ; Female ; Flow Cytometry ; Gene Silencing ; physiology ; Histocompatibility Antigens Class II ; genetics ; metabolism ; Mice ; Neoplasms ; immunology ; RNA Interference ; physiology ; RNA, Small Interfering ; genetics ; physiology ; Reverse Transcriptase Polymerase Chain Reaction