• BMB Reports
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• v.30 no.6
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• pp.385-389
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• 1997

Many cell types are known to stimulate $CD8^+$ T cells in allogeneic recognition such as mixed lymphocyte reaction (MLR). Whereas dendritic cells are most potent among them. T cells are usually considered very poor in stimulating $CD8^+$ T cells although there are some tumor cells that are weakly stimulatory. T cells, as a stimulator, cultured in the presence of concanavalin A that were otherwise nonstimulatory to $CD8^+$ T cells appeared to stimulate $CD8^+$ T cells strongly when they were pretreated with neuraminidase. The enhancement of MLR by neuraminidase could be achieved by treating either the stimulators or responders with neuraminidase. Removal of negatively-charged sialic acid moieties from the cell surface, which reduced electrostatic repulsion between responders and stimulators to give better cell-cell contact might be responsible for the enhanced MLR. In addition, neuraminidase treatment also appeared to deliver activation signal to responding T cells since it could activate $CD8^+$ T cells in synergy with phorbol myristate acetate. The maximal responses were observed when both responders and stimulators were treated with neuraminidase.

• BMB Reports
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• v.55 no.2
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• pp.57-64
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• 2022

Autoimmune disease is known to be caused by unregulated self-antigen-specific T cells, causing tissue damage. Although antigen specificity is an important mechanism of the adaptive immune system, antigen non-related T cells have been found in the inflamed tissues in various conditions. Bystander T cell activation refers to the activation of T cells without antigen recognition. During an immune response to a pathogen, bystander activation of self-reactive T cells via inflammatory mediators such as cytokines can trigger autoimmune diseases. Other antigen-specific T cells can also be bystander-activated to induce innate immune response resulting in autoimmune disease pathogenesis along with self-antigen-specific T cells. In this review, we summarize previous studies investigating bystander activation of various T cell types (NKT, γδ T cells, MAIT cells, conventional CD4⁺, and CD8⁺ T cells) and discuss the role of innate-like T cell response in autoimmune diseases. In addition, we also review previous findings of bystander T cell function in infection and cancer. A better understanding of bystander-activated T cells versus antigen-stimulated T cells provides a novel insight to control autoimmune disease pathogenesis.

• Molecules and Cells
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• v.42 no.3
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• pp.228-236
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• 2019

CD4 T cells differentiate into $ROR{\gamma}t/IL$-17A-expressing cells in the small intestine following colonization by segmented filamentous bacteria (SFB). However, it remains unclear whether SFB-specific CD4 T cells can differentiate directly from naïve precursors, and whether their effector differentiation is solely directed towards the Th17 lineage. In this study, we used adoptive T cell transfer experiments and showed that naïve CD4 T cells can migrate to the small intestinal lamina propria (sLP) and differentiate into effector T cells that synthesize IL-17A in response to SFB colonization. Using single cell RT-PCR analysis, we showed that the progenies of SFB responding T cells are not uniform but composed of transcriptionally divergent populations including Th1, Th17 and follicular helper T cells. We further confirmed this finding using in vitro culture of SFB specific intestinal CD4 T cells in the presence of cognate antigens, which also generated heterogeneous population with similar features. Collectively, these findings indicate that a single species of intestinal bacteria can generate a divergent population of antigen-specific effector CD4 T cells, rather than it provides a cytokine milieu for the development of a particular effector T cell subset.

• IMMUNE NETWORK
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• v.14 no.1
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• pp.21-29
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• 2014

Follicular helper T ($T_{FH}$) cells are recently highlighted as their crucial role for humoral immunity to infection as well as their abnormal control to induce autoimmune disease. During an infection, na$\ddot{i}$ve T cells are differentiating into $T_{FH}$ cells which mediate memory B cells and long-lived plasma cells in germinal center (GC). $T_{FH}$ cells are characterized by their expression of master regulator, Bcl-6, and chemokine receptor, CXCR5, which are essential for the migration of T cells into the B cell follicle. Within the follicle, crosstalk occurs between B cells and $T_{FH}$ cells, leading to class switch recombination and affinity maturation. Various signaling molecules, including cytokines, surface molecules, and transcription factors are involved in $T_{FH}$ cell differentiation. IL-6 and IL-21 cytokine-mediated STAT signaling pathways, including STAT1 and STAT3, are crucial for inducing Bcl-6 expression and $T_{FH}$ cell differentiation. $T_{FH}$ cells express important surface molecules such as ICOS, PD-1, IL-21, BTLA, SAP and CD40L for mediating the interaction between T and B cells. Recently, two types of microRNA (miRNA) were found to be involved in the regulation of $T_{FH}$ cells. The miR-17-92 cluster induces Bcl-6 and $T_{FH}$ cell differentiation, whereas miR-10a negatively regulates Bcl-6 expression in T cells. In addition, follicular regulatory T ($T_{FR}$) cells are studied as thymus-derived $CXCR5^+PD-1^+Foxp3^+\;T_{reg}$ cells that play a significant role in limiting the GC response. Regulation of $T_{FH}$ cell differentiation and the GC reaction via miRNA and $T_{FR}$ cells could be important regulatory mechanisms for maintaining immune tolerance and preventing autoimmune diseases such as systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA). Here, we review recent studies on the various factors that affect $T_{FH}$ cell differentiation, and the role of $T_{FH}$ cells in autoimmune diseases.

• Korean Journal of Veterinary Research
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• v.45 no.4
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• pp.501-505
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• 2005

Immu-Forte composed of chitosan, ${\beta}-glucan$, manno-oligosaccharide and pangamic acid was evaluated for its effectiveness as a nonspecific immunostimulator in mice. The effects of Immu-Forte were determined by analysis of cytokines using ELISA and phenotype of leukocyte subpopulations using monoclonal antibodies specific to mouse leukocyte differentiation antigens and flow cytometry. All T cells, all B cells, CD4 T cells, CD8 T cells, macrophages, IL-2, IL-4, IL-12 and IFN-r in Immu-Forte A-treated group increased in 1 months posttreatment and were significantly higher (p < 0.05) than that of control at 1 months posttreatment. All T cells, all B cells, CD4 T cells, CD8 T cells, macrophages and IL-2 in Immu-Forte EX-treated low and middle dose groups increased in 1 months posttreatment and were significantly higher (p < 0.05) than that of control at 1 months posttreatment. In the Immu-Forte soybean-treated group, NK cells and IL-4 were significantly higher in middle dose-treated group, and IL-2, IL-4 and IFN-r were significantly higher in low dose-treated group. In the Immu-Forte F-treated group, all T cells, all B cells, CD4 T cells, CD8 T cells, macrophages, NK cells, IL-2, IL-4, IL-12 and IFN-r in high dose-treated group and all T cells, all B cells, CD4 T cells, CD8 T cells, macrophages, IL-2, IL-4, IL-12 and IFN-r in middle dose-treated group and NK cells, IL-2, IL-4, IL-12 and IFN-r in low dose-treated group were significantly higher (p < 0.05) than that of control at 1 months posttreatment. In conclusion, this study has demonstrated that Immu-Forte had an immunostimulatory effect on mice through proliferation and activation of mouse immune cells.

• IMMUNE NETWORK
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• v.7 no.4
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• pp.173-178
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• 2007

Background: We studied the role for expression of CD40 and CD40L by CD4 and CD8 T cells in the generation of CD8 T cell response to minor histocompatibility antigen, H60. H60 is a cellular antigen to which CD8 responses require CD4 T cell help. Methods: CD40- or CD40L-deficient mice were adoptively transferred with normal CD4 or CD8 T cells or with memory CD4 or CD8 T cells, and were immunized with male H60 congenic splenocytes to induce CD8 T cell response to H60. Peripheral blood CD8 T cell from the immunized mice were stained with the H60 tetramer. Results: CD8 T cell response to H60 was not induced in both CD40- and CD40L-deficient mice. Adoptive transfer of $CD40^{+/+}$ CD8 T cells into CD40-deficient mice did not compensate the defect in inducing CD8 T cell response to H60, while the H60-specific CD8 T cells were activated in the CD40-deficient mice that were adoptively transferred with $CD40^{+/+}$ CD4 T cells. Adoptive transfer of $CD40L^{+/+}$ CD4 T cells into CD40L-deficient mice induced primary CD8 T cell response for H60 and the presence of $CD40L^{+/+}$ CD4 T cells was required even for memory CD8 T cells response to H60. Conclusion: Our results suggest that the CD40-CD40L interaction mediates the delivery of CD4 T cell help to naive and memory H60-specific CD8 T cells. While the expression of CD40L by CD4 T cells is essential, signaling through CD40 on CD8 T cells is not required for the induction of CD8 T cell response to H60.

• Molecules and Cells
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• v.44 no.5
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• pp.328-334
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• 2021

The advent of the major histocompatibility complex (MHC) multimer technology has led to a breakthrough in the quantification and analysis of antigen-specific T cells. In particular, this technology has dramatically advanced the measurement and analysis of CD8 T cells and is being applied more widely. In addition, the scope of application of MHC multimer technology is gradually expanding to other T cells such as CD4 T cells, natural killer T cells, and mucosal-associated invariant T cells. MHC multimer technology acts by complementing the T-cell receptor-MHC/peptide complex affinity, which is relatively low compared to antigen-antibody affinity, through a multivalent interaction. The application of MHC multimer technology has expanded to include various functions such as quantification and analysis of antigen-specific T cells, cell sorting, depletion, stimulation to replace antigen-presenting cells, and single-cell classification through DNA barcodes. This review aims to provide the latest knowledge of MHC multimer technology, which is constantly evolving, broaden understanding of this technology, and promote its widespread use.

• IMMUNE NETWORK
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• v.10 no.5
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• pp.153-163
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• 2010

Background: In addition to TCR and costimulatory signals, cytokine signals are required for the differentiation of activated CD8 T cells into memory T cells and their survival. Previously, we have shown that IL-12 priming during initial antigenic stimulation significantly enhanced the survival of activated CD8 T cells and increased the memory cell population. In the present study, we analyzed the mechanisms by which IL-12 priming contributes to activation and survival of CD8 T cells. Methods: We observed dramatically decreased expression of CD43 in activated CD8 T cells by IL-12 priming. We purified $CD43^{lo}$ and $CD43^{hi}$ cells after IL-12 priming and analyzed the function and survival of each population both in vivo and in vitro. Results: Compared to $CD43^{hi}$ effector cells, $CD43^{lo}$ effector CD8 T cells exhibited reduced cytolytic activity and lower granzyme B expression but showed increased survival. $CD43^{lo}$ effector CD8 T cells also showed increased in vivo expansion after adoptive transfer and antigen challenge. The enhanced survival of $CD43^{lo}$ CD8 T cells was also partly associated with CD62L expression. Conclusion: We suggest that CD43 expression regulated by IL-12 priming plays an important role in differentiation and survival of CD8 T cells.

• Biomolecules & Therapeutics
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• v.30 no.5
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• pp.418-426
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• 2022

Chimeric antigen receptor T (CAR-T) cell therapy is one of the promising anticancer treatments. It shows a high overall response rate with complete response to blood cancer. However, there is a limitation to solid tumor treatment. Additionally, this currently approved therapy exhibits side effects such as cytokine release syndrome and neurotoxicity. Alternatively, bispecific antibody is an innovative therapeutic tool that simultaneously engages specific immune cells to disease-related target cells. Since programmed death ligand 1 (PD-L1) is an immune checkpoint molecule highly expressed in some cancer cells, in the current study, we generated αCD3xαPD-L1 bispecific antibody (BiTE) which can engage T cells to PD-L1⁺ cancer cells. We observed that the BiTE-bound OT-1 T cells effectively killed cancer cells in vitro and in vivo. They substantially increased the recruitment of effector memory CD8⁺ T cells having CD8⁺CD44⁺CD62L^low phenotype in tumor. Interestingly, we also observed that BiTE-bound polyclonal T cells showed highly efficacious tumor killing activity in vivo in comparison with the direct intravenous treatment of bispecific antibody, suggesting that PD-L1-directed migration and engagement of activated T cells might increase cancer cell killing. Additionally, BiTE-bound CAR-T cells which targets human Her-2/neu exhibited enhanced killing effect on Her-2-expressing cancer cells in vivo, suggesting that this could be a novel therapeutic regimen. Collectively, our results suggested that engaging activated T cells with cancer cells using αCD3xαPD-L1 BiTE could be an innovative next generation anticancer therapy which exerts simultaneous inhibitory functions on PD-L1 as well as increasing the infiltration of activated T cells having effector memory phenotype in tumor site.

• YAKHAK HOEJI
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• v.53 no.3
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• pp.119-124
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• 2009

Cell-cell adhesion managed by various adhesion molecules plays an important role in regulating functional activation of cells. This event mediates attachment of inflammatory cells to endothelial cells, interaction of antigen-presenting cells with T cells and metastatic adherence of cancer cells to epithelial tissue cells. Therefore, this cellular response is considered as one of therapeutic target to treat various cancers and inflammatory diseases. To develop proper model for evaluation of functional activation of adhesion molecules, the ability of U937 and Jurkat T cells responsive to various adhesion inducers such as phorbal-12-myristate-13-acetate (PMA), staurosporin and monoclonal antibodies to CD29, CD43 and CD98 was investigated using quantitative cell-cell adhesion assay. U937 cells made more cell-cell clusters by the treatment of antibodies to CD29 and CD43 than Jurkat T cells, while Jurkat T cells exhibited increased cell-cell adhesion ability in CD98 antibody treatment. In agreement, the surface levels of CD29 and CD98 were highly observed in U937 and Jurkat T cells, respectively. Therefore, our data suggest that Jurkat T and U937 cells can be used for model system to evaluate functional activation of adhesion molecules such as CD29 and CD98.