Neuraminidase Treatment Enhances Allogeneic Stimulation of Unprimed CD8+ T Cells

Kim,Kilhyoun The Korea Science and Technology Center 1997 BMB Reports Vol.30 No.6

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.

Neuraminidase Treatment Enhances Allogeneic Stimulation of Unprimed CD8^+ T Cells

Kim, Kilhyoun 梨花女子大學校 藥學硏究所 1998 藥學硏究論文集 Vol.- No.7

Many cell types are know 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.

Differential Activation of T Cells by T-Cell Receptor Ligand Analogs

Kim,Kilhyoun,Choi,Yunhi,Suh,Yujin The Korea Science and Technology Center 1997 BMB Reports Vol.30 No.6

Although CD4+ T cell responses to protein-derived antigen have well been understood, the epitopes recognized by hapten-specific CD4+ T cells have not been fully defined. In this study, we characterized the response of a T cell hybridoma (5D10.1B8) which is specific for a hapten, N-hydroxysuccinimidyl-4-azidobenzoate (HSAB) restricted by MHC class Ⅱ I-A. Using three different antigen presenting cells (APCs) expressing I-A, the role of class Ⅱ MHC proteins in haptenic antigen presentation and subsequent activation of 5D10.1B8 has been examined. Activation of 5D10.1B8 T cells by HSAB analogs was also performed. Our results show that each APC activated T cells differentially and that interleukin-2 (IL-2) augmented antigen-presenting ability of all the APCs, suggesting that increased expression of class Ⅱ MHC protein by IL-2 played on important role in HSAB presentating and T cell activation. Finally, early T cell receptor-dependent signals induced by HSAB or its analogs were examined by phosphotyrosine immunoblot analysis, and showed that tyrosine phosphorylation level of a 18-20 kD protein increased upon stimulation.

Protective Immunity Induced by a Novel H-2Kb-restricted CTL Epitope from Hepatitis C Virus

Lim, Ok-Jae,Kim, Kilhyoun 이화여자대학교 약학연구소 2004 藥學硏究論文集 Vol.- No.13

Hepatitis C virus (HCV) is a noncytopathic, hepatropic virus that causes acute and chronic hepatitis and hepatocellular carcinoma. The cellular immune response to HCV is thought to be responsible for viral clearance and immunopathogenesis during the infection. Therefore, it is of great importance to define cytotoxic T lymphocyte (CTL) epitopes from HCV, which provides the basis of characterization of the CTL responses and development of T-cell vaccine against the infection In this study, a novel CTL epitope was defined and it was demonstrated that the epitope generated protective immunity against infection of recombinant vaccinia virus encoding HCV antigens. Twenty-three synthetic peptides, which were selected on the basis of H-2K^(b)-binding motif from HCV core and NS3 protein, were tested about their binding affinity to H-2K^(b)molecule by MHC-stabilizing assay using RMA-S cell line. 9 peptides showed relatively high binding capacity. AVA (AVAYYRGL) peptide drived from nonstructural (NS) 3 protein, showed relatively high proliferation stimulatory effect. The mice immunized with AVA peptide showed effective viral clearance. These results suggest that peptide vaccines can be antivirally protective in vivo, thus encouraging further search for appropriate peptides that may be used as T-cell vaccines.

Overcoming Tolerance in Hepatitis B Virus Transgenic Mice : A Possible Involvement of Regulatory T Cells

Roh, Sujin,Kim, Kilhyoun 梨花女子大學校 藥學硏究所 2003 藥學硏究論文集 Vol.- No.12

The hepatitis B virus (HBV) transgenic mouse (Tg) 50-4 strain is immunologically tolerant to HBV antigens. Various vaccination strategies have been attempted but failed to break the tolerance in the mouse. Although the tolerance to HBV antigen is maintained, this mouse strain develops spontaneous liver disease beginning at the age of about 3 months. We attempted to induce immune responses to HBV surface antigen (HBsAg) in the Tg by immunization with recombinant vaccinia virus expressing HBsAg (vvHBV), and observed different immunological responsiveness between 2-month-old and 5-month-old Tg. In contrast to the unbreakable tolerance reported previously, we could induce both the cytotoxic T lymphocyte (CTL) and the antibody response against HBsAg by the vvHBV immunization. The cytokine expression pattern indicated that T helper I type immune response was induced. However, interestingly, these immune responses were observed only in the 5-month-old Tg, but not in the 2-month-old Tg. Furthermore, CD4^(+) T cells from 2-month-old mice, but not those from 5-month-old mice, inhibited CTL response to HBV antigen when adoptively transferred to C57BL/6. These results suggest the possible involvement of regulatory T cell function in the HBV Tg for maintaining tolerance. This study would contribute to a better understanding of immune status of the HBV Tg as a model of human chronic hepatitis and to the search for new therapeutic targets for chronic viral infections.

Diversity and Complexity of CD8^+ T Cell Responses against a Single Epitope of Adenovirus E1B

Kim, Mihyung,Kim, Kilhyoun 梨花女子大學校 藥學硏究所 2002 藥學硏究論文集 Vol.- No.11

This study describes the characteristics of the immune responses against adenovirus in 057BL/6 mice. CTL responsescould be induced against E1Bp of adenovirus type 5, when whole viruses were immunized. A panel of ElBp-specific CTLclones showed a wide range of T cell avidity, Recognition of the E1BP Peptide and a panel of variant peptides containing asingle alanine substitution by CTL clones revealed that the fine specificity of the CTL response was quite diverse, rather thanbeing limited to a certain clonal preference. Moreover, the variant peptides with a substitution at the TCR contact residue hadantagonistic properties to some of the CTL clones, while being agonistic to others, reflecting the exxtensive diversity of the T cellsThese results imply fat the functional diversity of T cells to even a single epitope should be considered in manipulating immunityto viruses and in developing adoptive immunotherapy for imnunocompromised individuals.

Lymphoblastosis Inhibition and Plaque-forming Cell Response of Several Anti-inflammatory Steroids in Mice

Choi, Hong-Pil,Kim, Kilhyoun,Kim, Hyun-Pyo The Pharmaceutical Society of Korea 1992 Archives of Pharmacal Research Vol.15 No.2

Anti-inflammatory glucocorticoid (GC) derivatives have been clinically used in immune-malfunctional diseases for their immunosuppressive activity. However, there is still a lack of knowledge on the relationship between anti-inflammatory and immunosuppressive activities. In order to compare immunosuppressive activities with the known anti-inflammatory activities of the GC derivatives, eight clinically used GC derivatives including hydrocortisone, prednislone, 6$\alpha$-methyl prednisolone, triamcinolone, dexamethasone, betamethasone, triamcinolone acetonide and fluocinolone acetonide were selected, and lymphoblastosis inhibition and plaque-forming cell (PFC) response in mice were studied as immunological parameters. In Con A-induced lymphoblatosis inhibition invitro, all derivatives showed potent inhibition $IC_{50}$ values of the derivaties except methyl prednisolone and triamcinolone were less than $10^{-7}$M and good dose dependency was obtained. This result was well correlated with that of their anti-inflammatory potencies obtained. This result was well correlated with that of their anti-inflammatory potencies and their receptor binding affinities. However, in PFC response, consistent result were not obtained. Total numbers of PFCs per spleen were decreased by some derivatives, but numbers of PFCs per $10^6$ cells were not decreased by systemic administration of but numbers of PFCs per $10^6$ cells were not decreased by systemic administration of GC at the dose of 0.05 mg/mouse. Furthermore, at the dose of 0.1 mg/mouse, numbers of PFCs per $10^6$ cells were found to be increased, although total PFCs per spleen were decreased.

Telomerase Activity is Constitutively Expressed in the Murine CD8<SUP>+</SUP> T Cells and Controlled Transcriptionally and Post-Translationally

Sojung Kim,Mihyung Kim,Kilhyoun Kim 대한면역학회 2004 Immune Network Vol.4 No.3

Telomerase Activity is Constitutively Expressed in the Murine $CD8^+$ T Cells and Controlled Transcriptionally and Post-Translationally

Kim, SoJung,Kim, MiHyung,Kim, KilHyoun The Korean Association of Immunobiologists 2004 Immune Network Vol.4 No.3

Background: Telomerase, a ribonucleoprotein enzyme capable of synthesizing telomeric repeats, attracts attention for its possible role in determining the replicative capacity of normal somatic cells, transformed cells, and cells of the germline lineage. Differently from normal somatic cells with no telomerase activity, normal lymphocytes has been reported to have telomerase activity comparable to that found in transformed cells during development and activation, which substantiate a role in supporting the capacity of lymphocytes for extensive clonal expansion. Methods: Here, in order to define the telomerase regulation in murine T lymphocytes, telomerase activity in cloned murine $CD8^+$ T cells and naive $CD8^+$ T cells isolated from C57BL/6 mice was examined. Next, the regulatory mechanism of telomerase activity at transcriptional and post- translational levels was investigated by determining the expression level of the TERT protein, a key component for telomerase activity. Results: It was demonstrated that telomerase activity was expressed in an inactivated state as well as in an activated state in the murine $CD8^+$ T lymphocytes by using TRAP assay. The increase of telomerase activity was partially dependent on the net increase of TERT expression. Also, telomerase activity was decreased after treatment with protein kinase inhibitors, indicating that telomerase activation was prevented by inhibition of phosphorylation. Conclusion: Therefore, these results suggest that telomerase activity is constitutively expressed in the murine resting T lymphocytes and controlled by both transcriptional regulation and post- ranslational modifications.

Differential Activation of T Cells by T-Cell Receptor Ligand Analogs

Choi, Yunhi,Suh, Yujin,Kim, Kilhyoun 梨花女子大學校 藥學硏究所 1998 藥學硏究論文集 Vol.- No.7

Although CD4^+ T cell responses to protein-derived antigen have well been understood. the epitopes recognized by hapten-specific CD4^+ T cells have not been fully defined. In this study. we characterized the response of a T cell hybridoma (5D10.1B8) which is specific for a hapten. N-hydroxysuccinimidyl-4-azidobenzoate (HSAB) restricted by MHC class Ⅱ I-A^d. Using three different antigen presenting cells (APCs) expressing I-A^d. the role of class Ⅱ MHC proteins in haptenic antigen presentation and subsequent activation of 5D10.1B8 has been examined. Activation of 5D10.1B8 T cells by HSAB analogs was also performed. Our results show that each APC activated T cells differentially and that interleukin-2 (IL-2) augmented antigen-presenting ability of all the APCs, suggesting that increased expression of class Ⅱ MHC protein by IL-2 played an important role in HSAB presentation and T cell activation. Finally, early T cell receptor-dependent signals induced by HSAB or its analogs were examined by phosphotyrosine immunoblot analysis. and showed that tyrosine phosphorylation level of a 18-20 kD protein increased upon stimulation.