• Animal cells and systems
• /
• 제8권2호
• /
• pp.125-133
• /
• 2004

We have extended our previous work that cross-linking CD4 molecules using specific MAb induced antigen nonspecific, MHC unrestricted killing of virally infected target cells by CD$4^+$We have extended our previous work that cross-linking CD$4^+$ molecules using specific MAb induced antigen nonspecific, MHC unrestricted killing of virally infected target cells by CD$4^+$ T cells. The killing activity of antibody activated CD$4^+$T cells was completely blocked by herbimycin A, a protein tyrosine kinase (PTK) inhibitor, but not by bisindolylamaleimide, a protein kinase C (PKC) inhibitor. Herbimycin A treated human or bovine peripheral blood CD$4^+$T cells lacked PTK activity and failed to kill virally infected target cells even after cross-linking of CD4 molecules. The CD$4^+$cross-linking failed to induce effector cell proliferation or the transcription of TNF${\beta}$ Upregulation of TNF${\beta}$ was induced by incubating the antibody activated effector cells with BHV-1 infected D17 target cells for 10 h. Anti-TNF${\beta}$ antibody partially abolished (13-44%) the direct effector cell-mediated antiviral cytotoxicity. However, this antibody neutralized 70 to 100% of antiviral activity of effector and target cell culture supernatants against BHV-1 infected D17 cells. The inhibition level of the antiviral activity by the antibody was dependent on the effector and target cell ratio. These results support the hypothesis that increased p$56^ICK enzyme activity in effector cells transduces a signal critical for effector cell recognition of viral glycoproteins expressed on the target cells. Following target cell recognition, lytic cytokines known to participate in target cell killing were produced. A better understanding of the killing activity displayed by CD$4^+$T lymphocytes following surface receptor cross-linking will provide insight into the mechanisms of cytotoxic activity directed toward virally-infected cells.T cells. The killing activity of antibody activated CD$4^+$T cells was completely blocked by herbimycin A, a protein tyrosine kinase (PTK) inhibitor, but not by bisindolylamaleimide, a protein kinase C (PKC) inhibitor. Herbimycin A treated human or bovine peripheral blood CD4T cells lacked PTK activity and failed to kill virally infected target cells even after cross-linking of CD4molecules. The CD4 cross-linking failed to induce effector cell proliferation or the transcription of TNF$\beta$. Upregulation of TNF$\beta$ was induced by incubating the antibody activated effector cells with BHV-1 infected D17 target cells for 10 h. Anti-TNF$\beta$ antibody partially abolished (13-44%) the direct effector cell-mediated antiviral cytotoxicity. However, this antibody neutralized 70 to 100% of antiviral activity of effector and target cell culture supernatants against BHV-1 infected D17 cells. The inhibition level of the antiviral activity by the antibody was dependent on the effector and target cell ratio. These results support the hypothesis that increased $56^ICK enzyme activity in effector cells transduces a signal critical for effector cell recognition of viral glycoproteins expressed on the target cells. Following target cell recognition, lytic cytokines known to participate in target cell killing were produced. A better understanding of the killing activity displayed by CD$4^+$T lymphocytes following surface receptor cross-linking will provide insight into the mechanisms of cytotoxic activity directed toward virally-infected cells.

• 한양메디칼리뷰
• /
• 제33권1호
• /
• pp.10-16
• /
• 2013

Follicular helper T cells (Tfh) play a significant role in providing T cell help to B cells during the germinal center reaction, where somatic hypermutation, affinity maturation, isotype class switching, and the differentiation of memory B cells and long-lived plasma cells occur. Antigen-specific T cells with IL-6 and IL-21 upregulate CXCR5, which is required for the migration of T cells into B cell follicles, where these T cells mature into Tfh. The surface markers including PD-1, ICOS, and CD40L play a significant role in providing T cell help to B cells. The upregulation of transcription factor Bcl-6 induces the expression of CXCR5, which is an important factor for Tfh differentiation, by inhibiting the expression of other lineage-specific transcription factors such as T-bet, GATA3, and RORγt. Surprisingly, recent evidence suggests that CD4 T cells already committed to Th1, Th2, and Th17 cells obtain flexibility in their differentiation programs by downregulating T-bet, GATA3, and RORγt, upregulating Bcl-6 and thus convert into Tfh. Limiting the numbers of Tfh within germinal centers is important in the regulation of the autoantibody production that is central to autoimmune diseases. Recently, it was revealed that the germinal center reaction and the size of the Tfh population are also regulated by thymus-derived follicular regulatory T cells (Tfr) expressing CXCR5 and Foxp3. Dysregulation of Tfh appears to be a pathogenic cause of autoimmune disease suggesting that tight regulation of Tfh and germinal center reaction by Tfr is essential for maintaining immune tolerance. Therefore, the balance between Tfh and Tfr appears to be a critical peripheral tolerance mechanism that can inhibit autoimmune disorders.

• IMMUNE NETWORK
• /
• 제3권2호
• /
• pp.96-102
• /
• 2003

Background: Granulocyte-macrophage colony-stimulating factor (GM-CSF) gene-transduced tumor cell vaccines induce very potent systemic anti-tumor immunity in preclinical and clinical models. Our previous phase I clinical trial in patients with metastatic renal cell carcinoma (RCC) has demonstrated both immune cell infiltration at vaccine sites and T cell-mediated delayed-type hypersensitivity (DTH) response to whole tumor cell vaccines. Methods: To investigate the immune responses to autologous genetically- modified tumor cell vaccines, tumor-specific $CD8^+$ T cell lines were generated from peripheral blood lymphocytes (PBL) of a RCC patient 1.24 by repeated in vitro stimulation with either B7.1-transduced autologous RCC tumor cells or B7.1-transduced autologous tumor cells treated with interferon gamma ($IFN{\gamma}$), and cloned by limiting dilution. Results: Among several RCC-specific cytotoxic T lymphocytes (CTLs), a $CD4^+/CD8^+$ double positive T cell clone (17/A2) appeared to recognize $IFN{\gamma}$-treated autologous RCC restricted by HLA-B39. The 17/A2 also recognized other HLA-B39 positive RCC tumor cells after $IFN{\gamma}$ treatment. Conclusion: These results demonstrate that autologous RCC vaccination successfully generates the tumor-specific CTL 17/A2, and suggest that the presentation and recognition of the tumor antigen by the 17/A2 might be upregulated by $IFN{\gamma}$.

• 대한약학회:학술대회논문집
• /
• 대한약학회 2003년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.2-2
• /
• pp.130.1-130.1
• /
• 2003

As a potent antigen presenting cells and a powerful inducer of antigen specific immunity including cytotoxic T cell activity, dendritic cells(DCs) are being considered as a promising anti-tumor therapeutic module. Unlike solid tumors, leukemia is the hematologic malignancy involving immune effector cells. The expected usage of DCs in leukemia is the treatment of minimal residual disease(MRD) after the remission or stem cell transplantation. In this study, syngeneic leukemia cells were inoculated intra-venously into the mouse (WEHI-3 into the Balb/c), and the autologous tumor cell lysate pulsed DCs were injected as a therapeutic module twice in two weeks. (omitted)

• IMMUNE NETWORK
• /
• 제13권2호
• /
• pp.63-69
• /
• 2013

IL-12 is a secretory heterodimeric cytokine composed of p35 and p40 subunits. IL-12 p35 and p40 subunits are sometimes produced as monomers or homodimers. IL-12 is also produced as a membrane-bound form in some cases. In this study, we hypothesized that the membrane-bound form of IL-12 subunits may function as a costimulatory signal for selective activation of TAA-specific CTL through direct priming without involving antigen presenting cells and helper T cells. MethA fibrosarcoma cells were transfected with expression vectors of membrane-bound form of IL-12p35 (mbIL-12p35) or IL-12p40 subunit (mbIL-12p40) and were selected under G418-containing medium. The tumor cell clones were analyzed for the expression of mbIL-12p35 or p40 subunit and for their stimulatory effects on macrophages. The responsible T-cell subpopulation for antitumor activity of mbIL-12p35 expressing tumor clone was also analyzed in T cell subset-depleted mice. Expression of transfected membranebound form of IL-12 subunits was stable during more than 3 months of in vitro culture, and the chimeric molecules were not released into culture supernatants. Neither the mbIL-12p35-expressing tumor clones nor mbIL-12p40-expressing tumor clones activated macrophages to secrete TNF-${\alpha}$. Growth of mbIL-12p35-expressing tumor clones was more accelerated in the $CD8^+$ T cell-depleted mice than in $CD4^+$ T cell-depleted or normal mice. These results suggest that $CD8^+$ T cells could be responsible for the rejection of mbIL-12p35-expressing tumor clone, which may bypass activation of antigen presenting cells and $CD4^+$ helper T cells.

• IMMUNE NETWORK
• /
• 제4권2호
• /
• pp.88-93
• /
• 2004

Background: Bone marrow mesenchymal stem cells (MSC) inhibit the immune response of lymphocytes to specific antigens and dendritic cells (DC) are professional antigenpresenting cells whose function is to present antigen to naive T-lymphocytes with high efficiency and play a central role in the regulation of immune response. We studied the effects of MSC on DC to evaluate the relationship between MSC and DC in transplantation immunology. Methods: MSC were expanded from the bone marrow and DC were cultured from peripheral blood mononuclear cells (PBMNC) of 6 myelogenous leukemia after achieving complete response. Responder cells isolated from PBMNC and lysates of autologous leukemic cells are used as tumor antigen. The effect of MSC on the DC was analyzed by immunophenotype properties of DC and by proliferative capacity and the amount of cytokine production with activated PBMNC against the allogeneic lymphocytes. Also, cytotoxicity tests against leukemic cells studied to evaluate the immunologic effect of MSC on the DC. Results: MSC inhibit the CD83 and HLA-class II molecules of antigen-loaded DC. The proliferative capacity and the amount of INF-$\gamma$ production of lymphocytes to allogeneic lymphocytes were decreased in DC co-cultured with MSC. Also the cytotoxic activity of lymphocytes against leukemic cells was decreased in DC co-cultured with MSC. Conclusion: MSC inhibit the activation and immune response of DC induced by allogeneic or tumor antigen.

• 생명과학회지
• /
• 제16권6호
• /
• pp.904-910
• /
• 2006

수지상세포는 종양면역에서 필수적인 강력한 CTL 반응을 개시할 수 있는 유일한 세포이다 . 특히 외인성 종양항원에 대한 CTL 반응 유도는 활성화된 수지상세포의 IL-12 분비를 통한 CD4+ helper T세포의 cross-priming을 필요로 한다. 그러나 최근에 활성화된 수지상세포는 $Th_1$ 면역반응을 유도하지만 활성화 시간이 경과함에 따라 오히려 $Th_2$반응을 유도 할 수 있다. 따라서 본 연구에서는 OVA를 종양항원 모델로 설정하여 종양특이적인 CTL 반응을 형성하기 위한 최적의 수지상세포 활성화 조건을 조사하였다. 마우스 골수세포에 서 수지상세포로의 분화는 항원제시 기능을 위한 표면분자의 발현 측면에서 볼 때 배양 6일-7일 정도가 적합하였다. 수지상세포의 IL-12 생성능은 배양 6일 이상, OVA 항원 탑재 8시간 이상의 경우에 연이은 LPS 성숙자극으로 오히려 감소하는 경향을 보였다. 즉 배양 6일의 수지상세포에 OVA 항원 탑재를 8시간 수행한 경우(8-h DC)가 in vitro에서의 IL-12생성능, ex vivo에서의 세포내 $IFN-{\gamma}$를 발현하는 CD8+ T세포의 증가 및 OVA 특이적인 세포독성효과 등에서 가장 좋은 결과를 보였다. 또한 in vivo에서 종양 치료 및 예방효과에서도 8-h DC로 면역한 경우에 가장 우수한 종양형성 억제 효과와 생존기간 연장효과를 보였다. 현재 대부분의 수지상 세포를 이용한 항종양 백신에서 항원 탑재반응을 24시간 동안 수행하고 있으나, 본 실험의 결과로 볼 때, 8시간의 in vitro 항원 탑재가 보다 효과적인 종양특이적 CTL 반응과 항종양 면역반응을 유도함을 알 수 있다. 결론적으로 본 연구를 통하여 8시간 이상의 항원접촉은 수지상세포의 기능적 활성능력을 오히려 고갈시킬 수 있음을 제시한다.

• 한국가시화정보학회지
• /
• 제13권1호
• /
• pp.35-42
• /
• 2015

CD4+ T-cell count determines the effectiveness for antiretroviral therapy (ART) in patients with human immunodeficiency virus (HIV). Although ART slows the progression of HIV to AIDS, rapid counting of CD4+ T lymphocytes with a drop of patient's blood sample is urgently needed to ensure timely ART treatment in rural areas. Recently point-of-care CD4 testing devices have been developed by using non-flow based imaging cytometer incorporated with a sample cartridge where CD4+ T cells are reacted with fluorescently tagged specific antibodies. Here we conducted an experimental study using a conventional fluorescence microscope-based imaging system to quantitate the interaction of CD4 antibodies with CD4+ T cells at different reaction conditions. We demonstrated that a fast and affordable point-of-care CD4 test is feasible with a far less amount of antibodies and a shorter incubation time compared with a conventional sample preparation protocol for flow cytometry. We also proposed a general method to evaluate and compare the detection limit across different CD4 counting platforms by using fluorescently labelled microbeads for intensity calibration.

• IMMUNE NETWORK
• /
• 제22권1호
• /
• pp.4.1-4.22
• /
• 2022

In the era of immunotherapeutic control of cancers, many advances in biotechnology, especially in Ab engineering, have provided multiple new candidates as therapeutic immuno-oncology modalities. Bispecific Abs (BsAbs) that recognize 2 different antigens in one molecule are promising drug candidates and have inspired an upsurge in research in both academia and the pharmaceutical industry. Among several BsAbs, T cell engaging BsAb (TCEB), a new class of therapeutic agents designed to simultaneously bind to T cells and tumor cells via tumor cell specific antigens in immunotherapy, is the most promising BsAb. Herein, we are providing an overview of the current status of the development of TCEBs. The diverse formats and characteristics of TCEBs, in addition to the functional mechanisms of BsAbs are discussed. Several aspects of a new TCEB-Blinatumomab-are reviewed, including the current clinical data, challenges of patient treatment, drawbacks regarding toxicities, and resistance of TCEB therapy. Development of the next generation of TCEBs is also discussed in addition to the comparison of TCEB with current chimeric antigen receptor-T therapy.

• Journal of Microbiology
• /
• 제39권4호
• /
• pp.300-304
• /
• 2001

Epstein-Barr Virus(EBV)-transformed lymphoblastoid B cell lines, BLCL which expresse antigens, are potential antigen-presenting cells(APCs) for the induction of CTL in vitro. However transfection of BLCLs with subsequent selection by antibiotics is notoriously difficult because plating efficiencies of BLCLsare reported to be 1% or less. To generated stable transfectants of BLCLs we produced high titers of retroviruess encoding pp 65 antigen of human cytomegalovirus of foreign antigens and trans-duced them of BLCLs. The pp 65 gene was cloned into the retroviral vector pLXSN. The recombinant retroviral vector was transfected to ecotropic packaging cell line, CP&E86, and this polyclonal recom-binant retrovirus was transduced to PA317 that is amphotropic pakaging cell line. The titers of colned PA317 amphotropic retroviruses ranged from 5 to $\times$10$^{6}$ colony forming units (CFU)per ml (CFU/ml) We performed three rounds of consecutive transductions to BLCLs in order to improve the clon-ing effieiencies. The expression of recombinant HCMV-pp65 antigen was more than 20% after the final transduction. THe third-transduced BLCLs were easily selected in optimal concentration of G418. BLCLs expressing foreign antigens could be used as target cells for CTL assay and/or as APCs for induction of in vitro CTL responses specific for viral and tumor antigens.