| Summary: | 碩士 === 長庚大學 === 基礎醫學研究所 === 95 === The EBV-encoded oncoprotein LMP1 has been considered as one of the important cofactors in the carcinogenesis of nasopharyngeal carcinoma (NPC), which is an endemic cancer in Taiwan. NLMP1, with 10 amino acid deletion in C-terminus and several point mutations, isolated from Taiwan’s NPC biopsies has been found to be more tumorigenic and less immunogenic in BALB/c mice than BLMP1, the LMP1 originally identified in the prototype B95.8 strain. In the NLMP1 tumor animal model established in our laboratory, we have demonstrated the immunogenicity of NLMP1 to inhibit development of tumors expressing NLMP1 and have identified a CD8+ T epitope of NLMP1 (IYLEILWRL). In addition, we demonstrated that the CD4+ helper T cells play an important role in anti-NLMP1 tumor response. Dendritic cells present epitope on major histocompatibility complex (MHC) to activate naïve CD4+ T cells. Recently, many studies have shown that a Toll-like receptor ligand can stimulate immature DC to become type 1 DC (DC1), which can effectively activate naïve CD4+ helper T cells to become T helper type 1 (Th1) cells, followed by the activation of CD8+ cytotoxic T cells or natural killer (NK) cells, thereby eliminating tumor. Therefore, the identification of CD4+ T epitope of NLMP1 would be equally important to enhance additional anti-tumor effects by CD4+ cytotoxic T cells. In order to identify the CD4 epitope of NLMP1, we isolated normal BALB/c mouse splenic immature DCs, which could uptake exogenous tumor antigens. Subsequently, we stimulated the freshly purified DC with TLR ligands, specifically, a combination of LPS and poly(I:C) (L/P), and found that immature DC could be induced to become DC1. The CD4 epitopes of NLMP1 were predicted by the computer-based prediction algorithms (RANKPEP). Eight candidate peptides were selected and pulsed onto purified DC treated with LPS/poly(I:C) followed by the IFN-γ production assay. Finally, one of the eight candidate peptides was identified to be the CD4 epitope (HGPRHTDEH) located at the C-terminus domain in NLMP1.
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