• Journal of Life Science
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• v.16 no.6
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• pp.904-910
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• 2006

Dendritic cells (DCs) are the only antigen presenting cells (APCs) capable of initiating immune responses, which is crucial for priming the specific cytotoxic T lymphocyte (CTL) response and tumor immunity. Upon activation by DCs, CD4+ helper T cells can cross-prime CD8+ CTLs via IL-12. However, recently activated DCs were described to prime in vitro strong T helper cell type 1 $(Th_1)$ responses, whereas at later time points, they preferentially prime $Th_2$ cells. Therfore, we examined in this study the optimum kinetic state of DCs activation impacted on in vivo priming of tumor-specific CTLs by using ovalbumin (OVA) tumor antigen model. Bone-marrow-derived DCs showed an appropriate expression of surface MHC and costimulatory molecules after 6 or 7-day differentiation. The 6-day differentiated DCs pulsed with OVA antigen for 8 h (8-h DC) and followed by restimulation with LPS for 24 h maintained high interleukin (IL)-12 production potential, accompanying the decreased level in their secretion by delayed re-exposure time to LPS. Furthermore, immunization with 8-h DC induced higher intracellular $interferon(IFN)-{\gamma}+/CD8+T$ cells and elicited more powerful cytotoxicity of splenocytes to EG7 cells, a clone of EL4 cells transfected with an OVA cDNA, than immunization with 24-h DC. In the animal study for the evaluation of therapeutic or protective antitumor immunity, immunization with 8-h DC induced an effective antitumor immunity against tumor of EG7 cells and completely protected mice from tumor formation and prolonged survival, respectively. The most commonly used and clinically applied DC-based vaccine is based on in vitro antigen loading for 24 h. However, our data indicated that antigen stimulation over 8 h decreased antitumor immunity with functional exhaustion of DCs, and that the 8-h DC would be an optimum activation state impacted on in vivo priming of tumor-specific CTLs and subsequently lead to induction of strong antitumor immunity.

• Tuberculosis and Respiratory Diseases
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• v.44 no.1
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• pp.44-51
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• 1997

Background : The changes of the composition in the T-lymphocyte are important as an immunological abnormality in the pathogenesis of tuberculosis. Previously, the second type of TCR dimer(${\gamma}{\delta}$ T lymphocyte) that did not express CD4 or CD8 molecules was found. In other reports the presence of this type of lymphocytes was increased in the initial stage of tuberculous infections. Method : To determine whether there are some differences in the T-lymphocyte subsets in the peripheral blood or pleural effusion between pleural tuberculosis and other pleurisy. Thirty patients with pleural effusion among the forty-nine patients were examined T-lymphocyte subset analysis(CD4+T-cell,CD8+ T-cell,${\gamma}{\delta}$ T-lymphocytes) with anti- Leu4, anti-Leu3a, anti-Lea2a, anti HLA-DR and anti-TCR-${\gamma}{\delta}$-1(Becton & Dickinson Co.). Results : The average age of the patients was 50 years old(17-81year). There were 33 males and 16 female patients. Patiensts with tuberculosis are 30cases(tuberculous pleurisy 15), lung cancer 12cases(malignant effusion 9) and pneumonia 7cases(parapneumonic effusion 6cases) In T lymphocyte subsets of pleural effusion, helper T lymphocyte(54.6 + 13.8 %) of tuberculous pleurisy was higher than that(36.2 + 25.3 %) of non-tuberculous pleurisy(p=0.04). The peripheral blood ${\gamma}{\delta}$ T-lymphocytes in tuberculousis was insignificantly higher than non-tuberculous patients(p= 0.24). The peripheral blood ${\gamma}{\delta}$ T-lymphocytes and pleural ${\gamma}{\delta}$ T-Iymphocytes in tuberculous pleurisy was insignificantly higher than in non-tuberculous pleurisy(p= 0.16, p= 0.12). Conclusion : The percentage of -${\gamma}{\delta}$ T lymphocytes among the total T-lymphocytes is not significantly increased in the peripheral blood or pleural effusion of the pleural tuberculosis. ${\gamma}{\delta}$ T lymphocytes is less useful as a diagnostic method of pleural tuberculosis.

• Tuberculosis and Respiratory Diseases
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• v.43 no.1
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• pp.63-68
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• 1996

Background: Interferon-$\gamma$ has various biologic effects, including antiviral effect, antitumor proliferative effect, activation of macrophage and B lymphocyte, and increased expression of major histocompatibility complex. Especially, antitumor proliferative effect of interferon-$\gamma$ has already been proved to be important in vivo as well as in vitro. And, clinical studies of interferon-$\gamma$ have been tried in lung cancer patients. However, the mechanism of antitumor effect of interferon-$\gamma$ has not yet been established despite of many hypotheses. "Necrosis" is a type of cell death which is well known to occur in the circumstances of severe stresses. In contrast, "apoptosis" is another type of cell death which occurs in such biological circumstances as embryonic development, regression of organs, and self-tolerance of lymphocytes. And, apoptosis is an active process of cell death in which cells are dying with fragmentations of their cytoplasms and nuclei. And, in the process of apoptosis the DNAs of cells are cleaved between nucleosomes by unidentified endonuclease and therefore DNAs of apoptotic cells result in a typical electrophoresis pattern known as DNA ladder pattern. Recently it has been suggested that cytotoxic effect of interferon-$\gamma$ occurs via apoptosis. To elucidate the mechanism of antitumor cytotoxic effect of interferon-$\gamma$, we microscopically observed a lung cancer cell line, A549 which was treated with interferon-$\gamma$. We observed A545 treated with interferon-$\gamma$ was dying fragmented. And so, we performed this study to find out that the mechanism of antitumor cytotoxic effect of interferon-$\gamma$ be apoptosis. Method: We treated A549, human lung cancer cell line with various concentration of interferon-$\gamma$ and quantified its cytotoxic effect of various periods, 24 hours, 72 hours and, 120 hours by MTT(dimethylthiazolyl diphenyltetrazolium bromide) bioassay. Also, after we treated A549 with 100 units/mi of interferon-$\gamma$ for 120 hours, we observed the pattern of cell death with inverted microscope and we extracted DNAs from the dead A549 cells and observed the pattern of 1.5% agarose gel electrophoresis with ethidium bromide staining. Result: 1) Cytotoxic effect of interferon-$\gamma$ on A549: For the first 24 hours, threre was little cytotoxic effect and for between 24 hours and 72 hours, there was the beginning of cytotoxic effect and for 120 hours there was increased cytotoxic effect. 2) Pattern of A549 cell death by interferon-$\gamma$: We observed with inverted microscope that A549 cells were dying fragmented. 3) DNA ladder pattern of gel electrophoresis: We observed DNA ladder pattern of gel electrophoresis of extracted DNAs from dead A549 cells. Conclusion: We concluded that the mechanism of interferon-$\gamma$induced cytotoxicity on lung cancer cell line, A549 be via apoptosis.