The first complete mitogenome of skin beetles Omorgus chinensis (Coleoptera: Trogidae) with the phylogenetic implications.

The first complete mitogenome of Trogidae, Omorgus chinensis (Coleoptera: Trogidae) is sequenced using the next generation sequencing. The genomic structure is a circular molecule with 18682 bp in length, comprising 13 protein-coding genes, 22 transfer RNA genes (tRNAs), 2 ribosomal RNAs (rRNAs) and a control region. The nucleotide composition is A (39.44%), C (13.82%), T (36.78%), and G (9.96%) with an AT content of 76.22%. The phylogenetic analysis of 18 insects in Scarabaeoidae show that Omorgus chinensis shares a close ancestry with Lucanidae and Geotrupidae.

Enhancement of CD4(+) T cell response and survival via coexpressed OX40/OX40L in Graves' disease.

OX40/OX40L pathway plays a very important role in the antigen priming T cells and effector T cells. In the present study, we aimed to examine the involvement of OX40/OX40L pathway in the activation of autoreactive T cells in patients with Grave's disease (GD). We found that OX40 and OX40L were constitutively coexpressed on peripheral CD4(+) T cells from GD patients using flow cytometry analysis. The levels of OX40 and OX40L coexpression on CD4(+) T cells were shown to be correlated with TRAbs. Cell proliferation assay showed that blocking OX40/OX40L signal inhibited T cell proliferation and survival, which suggested that OX40/OX40L could enhance CD4(+) T cell proliferation and maintain their long-term survival in GD by self-enhancing loop of T cell activation independent of APCs. Confocal microscopy and coimmunoprecipitation analysis further revealed that OX40 and OX40L formed a functional complex, which may facilitate signal transduction from OX40L to OX40 and contribute to the pathogenesis of GD.

The expression of programmed death-1 in circulating CD4+ and CD8+ T cells during hepatitis B virus infection progression and its correlation with clinical baseline characteristics.

BACKGROUND/AIMS: Programmed death-1 (PD-1) expression was investigated in CD4(+) and CD8(+) T cells from hepatitis B virus (HBV)-infected patients at the chronic hepatitis B (CHB) infection, liver cirrhosis (LC), and hepatocellular carcinoma (HCC) stages. METHODS: PD-1 expression in circulating CD4(+) and CD8(+) T cells was detected by flow cytometry. The correlations between PD-1 expression and HBV viral load, alanine aminotransaminase (ALT) levels and aspartate aminotransferase (AST) levels were analyzed using GraphPad Prism 5.0. RESULTS: PD-1 expression in CD4(+) and CD8(+) T cells was significantly increased in both the CHB group and advanced-stage group (LC plus HCC). In the CHB group, PD-1 expression in both CD4(+) and CD8(+) T cells was positively correlated with the HBV viral load, ALT, and AST levels. However, in the LC plus HCC group, significant correlations between PD-1 expression and the clinical parameters were nearly absent. CONCLUSIONS: PD-1 expression in peripheral CD4(+) and CD8(+) T cells is dynamic, changes with HBV infection progression, and is related to HBV viral load and liver function, especially in CHB. PD-1 expression could be utilized as a potential clinical indicator to determine the extent of virus replication and liver injury.

[Effect of soluble PD-L1 released by lung cancer cells in regulating the function of T lymphocytes].

OBJECTIVE: To explore the expression of soluble programmed death ligand-1 on lung cancer cells and to clarify its biological function through PD-1/PD-L1 pathway in regulating the function of T lymphocytes. METHODS: Labeled monoclonal antibody and flow cytometry were used to analyze the expression of PD-L1 and its receptor PD-l on lung cancer cells and human T lymphocytes, respectively. The level of sPD-L1 in the supernatant of lung cancer cells was determined with an ELISA kit. The inhibition of proliferation of T lymphocytes by mPD-L1 and sPD-L1 was studied using CCK-8 incorporation. RESULTS: Low or no expression [(16.08 ± 2.28)%] of PD-1 was found on resting T lymphocytes from human peripheral blood with flow cytometry, but up-regulated expression of PD-1 [(78.06 ± 7.21)%] was found on the surface of activated T lymphocytes. Soluble PD-L1 was found in supernatant of some lung cancer cell lines, such as H1299, HO8910, SPCA-1, H460, H446 cells, with PD-L1 expressing on their cell surface [(78.34 ± 10.25)%, (68.17 ± 11.56)%, (45.32 ± 7.98)%, (47.52 ± 9.62)% and (40.95 ± 8.56)%, respectively], but very low expression on A549 cells [(16.02 ± 6.28)%]. The level of mPD-L1 on H1299 cells was highest [(78.34 ± 10.25)%], compared with HO8910 cells (68.17 ± 11.56)%, SPCA-1 cells (45.32 ± 7.98)%, H446 cells (40.95 ± 8.56)%, and H460 cells (47.52 ± 9.62)%. At the same time, the sPD-L1 level on H1299 cells was low [(0.17 ± 0.01) ng/ml], compared with HO8910 cells (0.30 ± 0.03) ng/ml, SPCA-1cells (0.59 ± 0.03) ng/ml, H446 cells (0.34 ± 0.02) ng/ml, and H460 cells (0.57 ± 0.03) ng/ml, but not expressed on A549 cells. PD-L1 expressing H1299 cells inhibited the proliferation of T lymphocytes in the co-culture system. Supernatant of the cultured PD-L1(+) lung cancer cells also inhibited T cell proliferation. Anti-human PD-L1 blocking antibody could partly restore the proliferation capacity of T lymphocytes. CONCLUSIONS: Membrane-bound PD-L1 and soluble PD-L1 released from lung cancer cells can effectively inhibit the proliferation of T lymphocytes in mixed culture system and down-regulate cell-mediated immunity in vitro. This may lead to inactivation of tumor antigen-specific T cells and immune escape of lung cancer cells.

Different roles of PD-L1 and FasL in immunomodulation mediated by human placenta-derived mesenchymal stem cells.

Mesenchymal stem cells (MSCs) derived from either bone marrow (BMSCs) or placenta (PMSCs) have the capacity to suppress immune responses to mitogenic and allogeneic stimulations. Both cell contact and soluble factor dependent mechanisms have been proposed to explain this immunosuppression. This study explored the roles of some of cell surface molecules expressed on human PMSCs (hPMSCs) in hPMSC mediated immunomodulation. hPMSCs strongly suppressed mitogen and allogeneic peripheral mononuclear cells (PBMCs) induced T cell activation and proliferation. hPMSCs constituently expressed programmed death-ligand 1 (PD-L1) and Fas ligand (FasL) molecules. Neutralising antibodies to-PD-L1 and FasL significantly reduced the suppressive effect of hPMSCs on T cell proliferation. However, only anti-PD-L1 antibody partially restored early T cell activation suppressed by hPMSCs. Anti-FasL antibody but not anti-PD-L1 antibody reduced apoptosis of activated T cell indicating that FasL molecule plays a role in inducing apoptosis of activated T cells, although overall hPMSCs diminished T cell apoptosis. Different effects of PD-L1 and FasL molecules on T cell activation and activated T cell apoptosis suggest that these two molecules influence T cell response at different stages. hPMSCs significantly prevented activated T cells from going into S phase. Both antibodies to PD-L1 and FasL had significant effect on reversing the effect of hPMSCs on cell cycles. hPMSCs reduced INF-γ but increased IL-10 production by mitogen activated T cells. Both antibodies partially abolished the effect of hPMSCs on INF-γ and IL-10 production. These data demonstrated that PD-L1 and FasL molecules play significant roles in immunomodulation mediated by hPMSCs. This study provides a rational basis for modulation of negative costimulators on hPMSCs to increase their immunosuppressive properties in their therapeutic applications.

[Expression of PD-1/PD-L1 in peripheral blood mononuclear cells in lung cancer patients and its biological significance].

OBJECTIVE: To analyze the expression of co-stimulatory molecules PD-1/PD-L1 in peripheral blood mononuclear cells in lung cancer patients, and to explore its biological significance. METHODS: One hundred and thirty-three lung cancer patients, 25 lung infection patients and 23 healthy donors were enrolled in this study. 100 µl of whole blood from these subjects were collected. Multi-color immunofluorescence staining and flow cytometry were used to detect PD-1/PD-L1 expression. The results were statistically analyzed. RESULTS: The expression level of CD3⁺CD8⁺ T cells in the lung cancer patients was (38.83 ± 1.74)%, significantly lower than that in the control group [(43.25 ± 3.35)%, P < 0.05]. CD8⁺CD28⁺ T cell subset in the peripheral blood of lung cancer patients was (17.73 ± 1.21)% significantly lower than that of the healthy donors [(27.96 ± 2.72)%, P < 0.01]. The CD8⁺CD28⁻ T cell subset was (21.19 ± 1.92)% in the lung cancer patients, significantly higher than that of the healthy control group [(15.18 ± 2.93)%, P < 0.05]. The expression level of PD-1 on the surface of CD8⁺CD28⁺ T cells was (10.67 ± 1.12)% in the group of lung cancer patients, significantly higher than that of the control group [(5.32 ± 1.58)%, P < 0.01]. It was also found that the expression of PD-1 on CD8⁺CD28⁻ T cells was up-regulated in the group of lung cancer patients (7.46 ± 1.25)%, significantly higher than that of the healthy control group [(2.68+1.07)%, P < 0.01]. The expression level of PD-L1 on CD68⁺ cells in the lung cancer patients was (16.03 ± 2.06)%, significantly higher than that of the healthy control group [(9.32 ± 2.00)%, P < 0.05]. CONCLUSION: Up-regulation of PD-1/PD-L1 on peripheral blood cells in lung cancer patients negatively regulates the lymphocytes, inhibits the immune response for killing tumor cells, and promotes tumor development and immune escape.

[Expression of B7-H3 costimulatory molecule in peripheral blood of myasthenia gravis patients].

AIM: To reveal the clinical significance of B7-H3 costimulatory molecule in myasthenia gravis (MG) patients by analyzing membranous B7-H3 (mB7-H3) and soluble B7-H3 (sB7-H3) expressions. METHODS: We collected peripheral blood samples of 35 MG patients and 44 health controls (HC) and detected the expression of mB7-H3 on peripheral blood mononuclear cells (PBMCs) using flow cytometry. ELISA was performed to analyze the levels of sB7-H3 in plasma samples from MG patients and HC. RESULTS: There was no significant difference in the expressions of mB7-H3 on T lymphocytes, monocytes or B cells between MG patients and HC. However, the level of sB7-H3 from MG patients was (2.166±0.958) ng/mL, significantly lower than that from HC (3.379±0.768) ng/mL. The level of sB7-H3 in general MG (GMG) patients (1.664±0.699) ng/mL was lower than that in ocular MG (OMG) patients (2.396±0.985) ng/mL. In MG patients complicated with abnormal thymus, the level of sB7-H3 was (1.593±0.441) ng/mL, also lower than that in MG patients with normal thymus (2.364±1.014) ng/mL. In addition, a significant negative correlation was found between the levels of sB7-H3 and QMGS in MG patients (r=-0.4189, P=0.012), but sB7-H3 was not associated with mB7-H3 in MG patients. CONCLUSION: In MG patients, down-regulation of sB7-H3 is finely correlated to the severity of the disease. Its different expression levels in various types of MG patients indicate that this costimulatory molecule may be involved in the immunopathogenesis of MG.

[The level of soluble programmed death-1 in peripheral blood of patients with lung cancer and its clinical implications].

OBJECTIVE: To analyze the expression of soluble programmed death-1 ligand 1 (sPD-L1) in the serum of patients with lung cancer and to explore its biological and clinical implications. METHODS: Fifty-five male and twenty-six female lung cancer patients ages 34 to 87 years (mean age 65 ± 6) were selected from the Department of Respiratory Diseases in The Second Affiliated Hospital of Soochow University from June 2009 to March 2011. All lung cancer patients were newly-diagnosed, treatment-free and confirmed by histopathology or cytopathology. Eight-eight healthy volunteers matching in sex and age from the Healthcare Center of the hospital were also enrolled as controls. The sPD-L1 protein expression in serum was determined by Western blot and self-developed ELISA kit. Fluorescence-labeled monoclonal antibody and cytometry were used to examine changes in lymphocyte subsets in the peripheral blood of lung cancer patients and healthy controls. RESULTS: A higher level of sPD-L1 level in the lung cancer patients [1.6 (0.7 - 7.8) µg/L] was found compared to the control group [0.9 (0.4 - 3.7) µg/L] (P < 0.001). High expression of sPD-L1 in the lung cancer patients was closely correlated to lymph node metastasis and the extent of distant metastasis (χ(2) = 5.636, P < 0.05; χ(2) = 4.601, P < 0.05). The sPD-L1 level in lung cancer patients with objective response to treatment (complete response + partial response) was 2.7 (1.6 - 7.0) µg/L and 1.1 (0.8 - 1.7) µg/L before and after treatment, respectively (P < 0.01). The level of sPD-L1 with progression disease was 1.9 (1.3 - 8.5 µg/L) which was significantly increased compared to the baseline level 1.4 (0.8 - 2.2) µg/L (P < 0.01). Additionally, abnormal changes of T and B lymphocytes and their subsets were found, with a significant decrease of CD(8)(+) T lymphocytes (P < 0.05) and a rise in CD(4)/CD(8) ratio (P < 0.05). Further double-labeling study showed increased percentages of CD(4)(+)PD-1(+) T lymphocytes and CD(8)(+)PD-1(+) T lymphocytes (P < 0.05). CONCLUSIONS: The elevated expression of sPD-L1 in lung cancer patients was closely related to lung cancer staging, metastasis and clinical response. sPD-L1 may become a predictive marker and an important anti-tumor target in individualized treatment of lung cancer.

[Preparation and characterization of three novel monoclonal antibodies against human PD-L1].

AIM: To prepare a functional mouse anti-human PD-L1 monoclonal antibody and to characterize its biological activities. METHODS: A stable human PD-L1 transfected cell line L929/PD-L1 was used as an antigen to immunize BALB/c mice. By means of the cell fusion technique, multiple cell subcloning, repeated screening with L929/ PD-L1 as target cells and the L929/mock cells used as the negative control, the hybridomas specifically secreting mouse anti-PD-L1 monoclonal antibodies were generated. Then its biological characterization was investigated by rapid murine Ig-subclass typing, Western blotting, indirect immune of luorescene assay, mutual competitive inhibition test. By means of MTT incorporation assay, detected the infection of mAb to T cell proliferation. Three mouse anti-human PD-L1 monoclonal antibodies were generated, named as 11G8, 2G5 and 5C3. RESULTS: The results of characterization study showed that the monoclonal antibodies could recognize the PD-L1 on the activated T cells. The mAbs could promote T cells proliferation. CONCLUSION: It is evident that the functional monoclonal antibodies for human PD-L1 have been generated, and it would provide the initial material for further study on the role of PD-1/PD-L1 signaling pathways.

[Construction of murine CXCR3 gene transfected cell line, identifiction and study of its biological function].

AIM: To construct recombinant murine CXCR3 gene retroviral vector and obtain L929-mCXCR3 gene transfected cell line for stably expressing murine CXCR3. We further study on L929-mCXCR3 migration effect resulted from interaction by CXCR3 and its ligand IP-10. METHODS: One female BALB/c mouse (7 weeks) was injected with 0.5 mg Con A intravenously (i.v.) via a tail vein. Twelve hours later the mouse was sacrificed and the spleen was removed.The spleen was pressed through a 150 microm stainless steel mesh. The isolated splenocytes were cultured in RPMI1640 supplemented with 50 U/mL human IL-2 for 3 days.Total RNA was extracted with TRIzol. Murine CXCR3 gene of full length was amplified by RT-PCR, then, it was inserted into retrovirus vector pEGZ-term. The recombinant vector together with its helper virus vector were co-transfected into package cell 293T with Lipofectamine(TM); 2000.The supernatant of 293T was collected for infecting L929 cells (repeated three times), and cell clones stably expressing murine CXCR3 molecule were screened by zeocin(500 mg/L). We used FCM and RT-PCR to verify expression of CXCR3 from protein level and gene level, respectively. Studied migration ability of L929-mCXCR3 interacted with its ligand IP-10 by transwell system. RESULTS: We have constructed recombinant murine CXCR3 gene retroviral vector and obtained L929-mCXCR3 gene transfected cell line which can stably expressing murine CXCR3 molecule. Positive expression rate of membrane is 97.0%, and it can directly migrate induced by IP-10, the chemotatic index is 4.356%. CONCLUSION: Construction of L929-mCXCR3 cell line has laid a good foundation on research of biologic characteristics of CXCR3 signal path , establishment of tumor metastasis model and preparation of anti-murineCXCR3 monoclonal antibody.

[Expression of human PD-1Deltaex3 and primary study of its biological activity].

AIM: To express human PD-1Deltaex3(DeltaPD-1) gene in eukaryotic expressing vector and identify the biological activity of the recombinant protein. METHODS: The target gene encoding full length human PD-1(PD-1) was cloned by RT-PCR, then two fragments of PD-1Deltaex3 gene were amplified and assembled by TP-PCR, PD-1Deltaex3 gene was obtained. Then the two genes PD-1 and DeltaPD-1 were inserted into the eukaryotic expressing vector pIRES2-EGFP respectively to construct the recombinant vectors pIRES2-EGFP/PD-1 and pIRES2-EGFP/DeltaPD-1. The recombinants were transfected into 293T cells with Lipofect2000 Reagent. The membrane PD-1 protein on the transfected cell surface was detected by flow cytometry. The expression of soluble PD-1 was also analysised by Western blot. The combination of DeltaPD-1 protein to the ligands of PD-1, PD-L1 and PD-L2, were determined by indirect immunofluorescence assay. RESULTS: The results of enzyme digestion of recombinant vectors and DNA sequencing showed the two genes PD-1 and PD-1Deltaex3 were inserted correctly into plasmid pIRES2-EGFP, the two recombinant vectors were constructed successfully. Flow cytometry and Western blot revealed that 293T cells transfected with vector pIRES2-EGFP/PD-1 could express PD-1 protein on the cell surface but no soluble PD-1 in the supernatant of transfected cells, on the contrary, 293T cells transfected with vector pIRES2-EGFP/DeltaPD-1 could express soluble PD-1 in the culture supernatant but no membrane PD-1. Indirect immunofluorescence assay indicated the DeltaPD-1 protein could bind to the two ligands of PD-1 on the cells surface. CONCLUSION: The recombinant eukaryotic expressing vector containing PD-1Deltaex3 was constructed successfully, and the PD-1Deltaex3 gene could encode a soluble form of PD-1 protein. DeltaPD-1 protein remained the biological activity as PD-1. This study provides the initial material for further study of PD-1Deltaex3 in PD-1/PD-L signaling pathway.

[Generation and preliminary functional study of a CD133-2-harboring L929 cell line].

AIM: To generate an engineered L929 cell line harboring human CD133-2 and perform the functional study of the gene-modified cell line. METHODS: The human CD133-2 gene was obtained by PCR from a cDNA library of foetus liver. After digested with Hind III and BamH I, the PCR product was cloned into pIRES2-EGFP vector. The recombinant plasmid CD133-2/pIRES2-EGFP was transfected into L929 cell line using lipofectamine, followed by G418 selection. RT-PCR, Western blot and flow cytometry (FCM) were used to detect the expression of CD133-2. MTT was used to analyze the effect of the CD133-2/L929 cells on proliferation of T cells. FCM was performed to monitor T cell activation by detecting T cell surface markers of CD4CD25 and CD8CD25 after T cells were cocultured with the CD133-2/L929 cells in the presence of an anti-CD3 mAb. RESULTS: A stable cell line constitutively expressing the human CD133-2 was established successfully. In the presence of the anti-CD3 mAb, CD133-2/L929 cells caused inhibition of T cell proliferation and down-regulation of the activation markers of CD4CD25 and CD8CD25 on T cells. CONCLUSION: The engineered CD133-2/L929 cell line provides a gain-of-function cell model for further understanding the biological role of CD133-2.

[Inhibitory and lethal effects of human-mouse chimeric antibody against CD80 on the growth of B lymphoma cell lines Raji and Daudi].

AIM: To study the inhibitory and lethal effects of human-mouse chimeric antibody against CD80 (named ch-4E5) on the growth of B lymphoma cell lines Daudi and Raji. METHODS: Immunofluorescence and flow cytometry were used to analyze the detection of membrane CD80 in Raji and Daudi by ch-4E5. After the co-culture of ch-4E5 with Raji and Daudi, respectively, at the final concentration of 10 mg/L, the expression of Fas and FasL was observated to be at the 0 h, 4 h, 10 h, 16 h, 24 h and 48 h by direct immunofluorescence and flow cytometry, and the blocking effect on cell growth of ch-4E5 was determined at 72 h by MTT assay. MTT assay was also used to study the ADCC effect with PBMC as effector cells and Raji and Daudi as target cells. The efficiency target ratio was 20:1. RESULTS: The combination rate between ch-4E5 and Raji and Daudi was 98.6% and 96.4%, respectively. After the co-culture of ch-4E5 with Raji and Daudi cells for 4 hs, the expression of FasL in Raji began to up-regulate. It reached the peak at 16 h and its positive rate was 16.8%. Compared with human IgG1 control group, it was increased obviously (P<0.01). The expression of Fas increased at 10 h, and then reached the top at 24 h. The combination rate was 15.6%. There was significant deviation compared with human IgG1 control group (P<0.01). Moreover, the expression of FasL and Fas on Daudi was also altered. The trend was similar to these on Raji, and the highest expression was 15.9% and 13.7%, respectively. The inhibitory rate was 34.60% and 32.64% respectively when ch-4E5 with Raji and Daudi had been co-cultured for 72 h (P<0.01). Furthermore, ch-4E5 could mediate the ADCC effect and the maximum killing rate was 55.61% and 54.42%, respectively(P<0.01). CONCLUSION: The human-mouse chimeric antibody against CD80 can inhibit the proliferation of B lymphoma cell lines Daudi and Raji cells through Fab and Fc sections in vitro.

Fine-tuned expression of programmed death 1 ligands in mature dendritic cells stimulated by CD40 ligand is critical for the induction of an efficient tumor specific immune response.

During maturation, murine myeloid dendritic cells (DCs) upregulated the expressions of CD11c, CD25, CD40, CD80, CD86, MHC II and programmed death 1 ligands 1 and 2 (PD-L1 and PD-L2). Differential expression patterns of PD-L1 and PD-L2 were found when DCs were triggered by CD40 ligand and TNF-alpha. PD-L1 expression was repressed and PD-L2 expression remained unchanged in mature CD40-ligated DCs, whereas TNF-alpha stimulated DCs kept high expression of PD-L1 and significantly enhanced PD-L2 expression on DCs. Proliferations of T lymphocytes stimulated by immature DCs were enhanced by blockade of the PD-1 and PD-1 ligand interaction. But inhibitive effects were found in T lymphocytes stimulated by CD40-ligated DCs. With the fine-tuned expressions of PD-L1 and PD-L2, CD40-ligated DCs could sustain a longer activation period and elicit a more efficient T lymphocyte activation.

[Construction of anti-CD28 single chain antibody genes and expression of the ScFv in BmN cells and the larvae of Bombyx mori].

The V(H) and V(L) gene fragments of anti-CD28 mAb were combined to form anti-CD28 ScFv gene by using TP-PCR method. Sequence analysis showed that 6 x His tag was added to it for the ease of purification and the V(H), and V(L) gene fragments were connected by a linker containing 15 amino acids which are biased by the baculovirus promoter, ph. Then ScFv gene fragment was inserted into baculovirus transfer vector pBacPAK8. The recombinant transfer vector, pBacPAK8/CD28-ScFv was constructed successfully. The pBacPAK8/CD28-ScFv and the linear Bm-BacPAK6 were co-transfected into the cell line of Bombyx mori (BmN) with the help of Lipofectin,then the product was purified by plaque assay and identified by PCR method. The recombinant virus, Bm-BacPAK6 CD28-ScFv, was obtained successfully. The BmN cells and the larvae of Bombyx mori were infected by the recombinant baculovirus and harvested every 24h postinfection. SDS-PAGE and Western Blotting analysis confirmed the expression of ScFv with the molecular weight of about 28 kD. The expression in BmN cells was detected 24h post infection and it peaked at 72 h, while in the larvae of Bombyx mori, the expression was detected 48 h post infection and it peaked at 120 h.

[Preparation and characterization of two novel functional monoclonal antibodies against human OX40L].

AIM: To prepare novel anti-OX40L functional monoclonal antibodies and characterize their distinct biological functions. METHODS: Routine immunization of BALB/c mice by a tansfected cell line L929/OX40L expressing high level of OX40L as antigens. Then fuse the immunized spleen with Sp2/0, a kind of myloma, and screen the positive clones by FCS with L929/OX40L as a positive control.After acquisition of the hybidomas secreting anti-OX40L mAb, investigation of their biological activities by Western blot, rapid isotyping analysis, karyotype analysis, competitive inhibition test, indirect immunofluorescence and MTT incorporation assay were followed. RESULTS: Obtain two stable hybridomas, 4D6 and 5C2, which could continuously secret specific anti-OX40L monoclonal antibodies. The following biological activity studies showed that these monoclonal antibodies could both recognize the natural OX40L expressed on the mature DC, especially the OX40L on the several leukemia cell lines, such as Jurkat, SHI-1, U937 etc. Furthermore, they could also suppress the proliferation of SHI-1 in vitro. CONCLUSION: Two hybridomas secreting anti-OX40L monoclonal antibodies continuously and steadily have been established. These monoclonal antibodies could specifically recognize human OX40L and effect the proliferation of leukemia cell line SHI-1 through OX40/OX40L costimulatory signals.

[Expression of human-mouse chimeric antibody against CD40 in CHO cell line and characterization of its function].

AIM: To investigate the stable expression of a chimeric antibody against CD40 moleculeèch-5C11éin CHO and its biological activity. METHODS: Human-mouse chimeric antibody against CD40 recombinant plasmid and mock plasmid were transfected into CHO cell line through lipofectamine mediation. Human kappa chain and Fc fragment of ch-5C11 were characterized by FACS and Western blot. The concentration of ch-5C11 in cell supernatants was detected by Lowry assay and the inhibitory effect of ch-5C11 on the proliferation of Daudi cells was detected by MTT assay. RESULTS: RT-PCR showed that target CHO cells integrated chimeric heavy chain and chimeric light chain gene. FACS and Western blot showed that ch-5C11 in cell supernatants maintained the binding activity and specificity to human CD40 molecule, and contained human kappa chain and Fc fragment. Cell supernatants were purified using protein G affinity chromatography. The concentration of human-mouse chimeric antibody against CD40 in cell supernatants was 0.535 mg/L. When co-cultured with B lymphoma cell line Daudi, ch-5C11 induced proliferation arrest of Daudi cells. CONCLUSION: The human-mouse chimeric antibody against CD40 can be expressed in CHO stably and effectively, which inhibits proliferation of Daudi.

[Establishment of cell line transfected with human BTLA gene and preliminary study on its biological function].

AIM: To establish 293T cells expressing human BTLA gene, a novel attenuator for B and T lymphocyte. METHODS: The gene encoding human BTLA was amplified by RT-PCR from PHA activated T cells, and then the target gene fragment was inserted into retrovirus vector pEGZ-Term after being digested with EcoR I and BamH I. The recombinant vector was transfected into 293T cells with LipfectAMINE 2000, and the cells was further selected with Zeocin. Effect of 293T/BTLA cells on T cells proliferation and activation in vitro was been studied by methods of MTT and cytometry. RESULTS: The stable expression of human BTLA on the transfected cell line was identified by flow cytometry analysis. In vitro, 293T/BTLA cells had an inhibitory effect on the proliferation of T cells stimulated by anti-CD3 mAb and down-regulated the expression of activation marker CD25 on the surface of T cells and decreased the secretion of IFN-gamma and IL-10. CONCLUSION: A cell line 293T/BTLA stably expressing the human BTLA protein has been obtained and it can partially inhibit the proliferation and activation of T cells in vitro.

Recombinant human B7-H4 expressed in Escherichia coli inhibits T lymphocyte proliferation and IL-2 secretion in vitro.

AIM: To explore the biofunctions of human B7-H4 generated from prokaryotic system. METHODS: The gene of human B7-H4 extracellular region (IgV-like and IgC-like domains) was obtained by PCR from human cDNA FLJ22418 and then inserted into the prokaryotic expression vector pGEX-5X-3 expressing glutathione s-transferase (GST) fusion protein. After being identified by restriction enzyme digestion and sequencing, the recombinant vector was transferred into host strain E coli BL21-RIL(DE3). A 47 kDa fusion protein (GST/hB7-H4) was induced by isopropyl-beta-D-thiogalactopyranoside (IPTG) and purified by standard methods reported in the prokaryotic system. The inhibitory effect of GST/hB7-H4 on proliferation of T cells was observed in vitro by CD3mAb activated T-cell culturing system and [(3)H]-thymidine incorporation assay. The concentrations of interleukin-2 and iterferon-g in the supernatants of T cells were determined by ELISA. RESULTS: We successfully constructed the method for high-level expression and purification of the hB7-H4 extracellular domain as GST fusion protein from E coli. The GST/hB7-H4 fusion protein produced in bacteria had obvious biological activity to inhibit T-lymphocyte proliferation and IL-2 secretion. CONCLUSION: The prokaryote expression system could be used to generate hB7-H4 protein with natural spatial conformations and biological functions, which provided an efficient and economical way for the preparation of this target protein.

[Construction and expression of human-mouse chimeric antibody against human CD40].

AIM: To construct and express a chimeric antibody against human CD40 molecule by genetic engineering antibody transformation. METHODS: Total RNA was extracted from the murine hybridoma cell 5C11 which secreted anti-CD40 monoclonal antibody (mAb). The genes encoding V(H) and V(L) of mAb 5C11 were amplified by RT-PCR. According to sequence analysis, the primer was designed to amplify signal peptide sequences relative to V(H) and V(L) genes. The V(H) and V(L) genes of mAb 5C11 and relative signal peptide sequences were spliced with C(H) and C(kappa) genes of human IgG1 to construct expression plasmid pIRES/h5C11 of human-mouse chimeric antibody gene and the plasmid was transfected into 293T cells under Lipofectamine mediation for transient expression. Expressed product was analyzed by flow cytometry. RESULTS: The result of NCBI gene data bank blast revealed that cloned gene sequence accorded with mice' V(H) and V(L) genes and feature of signal peptide sequence. The constructed plasmid pIRES/h5C11 was correct. The restriction endonuclease digestion analysis and PCR showed that the recombinant genes were subsequently cloned into vector pIRES. FACS analysis showed that human-mouse chimeric antibody against human CD40 maintained the binding activity and specificity to human CD40 molecule. CONCLUSION: The gene encoding variable region of human-mouse chimeric antibody against CD40 is cloned successfully and the human-mouse chimeric antibody against CD40 is expressed transiently in 293T cells.