| Summary: | 博士 === 國立臺灣大學 === 微生物學研究所 === 86 === ABSTRACT
The successful T cell responses against tumor are dependent on the molecular
interaction between tumor cells and T cells and the cytokine repertoire
present at the tumor site. It was demonstrated that the weak immunogenicity
and the inefficiency of tumor cells in inducing tumor-specific T cells was
resulted from insufficient expression of major histocompatibility complex
(MHC) or accessory molecules. In the present study, we demonstrated that
upregulating the expression of intercellular adhesion molecule-1 (ICAM-1)
on tumor cells by the 8-MOP/UVA treatment could enhance the immunogenicity
of tumor and resulted in growth inhibition of the unmodified tumor cells.
Failure of an antitumor immune response could also be related to the defects
of immune regulation at tumor site. Some tumor cells may secrete certain
immunosuppressive factors to modify the host immune responses. Moreover,
the inability of adequate activation of tumor-specific cytotoxic T cells
might be due to the insufficient generation of tumor-specific Th cells which
can provide the proper cytokine regulation at the tumor site. In our
present investigation, we recruited and cognated tumor cells with OVA-primed
Th cells by immunizing the OVA-sensitized mice with irradiated OVA-pulsed
cells. We demonstrated here that the immunogenicity of tumor cells was
augmented and the growth of the subsequently challenged tumor could be
inhibited by tumor-specific CD8+ T cells.
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