CTL识别的HLA-A2限制性人卵巢癌相关抗原OVA66表位的鉴定

Identification of a novel HLA-A2-restrictive CTL epitope of an ovary cancer-associated antigen OVA66

目的: 鉴定CTL识别的HLA A2限制性人卵巢癌相关抗原OVA66表位。方法: 以细胞因子从外周血单个核细胞(PBMC)中诱导树突状细胞(DC), 通过形态学观察和流式细胞术进行鉴定。用表位预测法选取并合成两种肽分子, 分别脉冲成熟的DC, 并刺激HLA- A2+健康人自体CD8+ T细胞。1wk后, 用脉冲肽的自体PBMC以每 7d的间隔刺激该CD8+T细胞 3次。以共接受 4次抗原肽刺激的T细胞作为CTL,用乳酸脱氢酶(LDH)释放试验, 检测CTL对靶细胞的杀伤效应。用酶联免疫斑点法 (ELISPOT), 检测CTL中抗原特异性分泌IFN- γ的T细胞数。结果: 形态学和流式细胞术的结果显示, PBMC可诱生成熟的DC。肽L235(FLPDHINIV)诱导的CTL, 可特异性杀伤L235脉冲的T2细胞和OVA66+、HLA A2+的SW480细胞, 且L235诱导的特异性分泌IFN- γ的T细胞数增加。结论: 卵巢癌相关抗原OVA66的HLA A2限制性CTL表位L235, 能激发对肿瘤抗原的特异性免疫应答, 为制备肿瘤特异性肽疫苗奠定了实验基础。

AIM: To identify a novel HLA-A2-restrictive CTL epitope of an ovary cancer-associated antigen OVA66. METHODS: Dendritic cells(DCs), induced from peripheral blood mononuclear cells(PBMCs) by cytokines, were confirmed by morphological observation and FACS. Mature DCs were pulsed with each of the two synthesized peptides which were selected as possible CTL epitopes by software analysis. The pulsed DCs were used to stimulate autologous CD8+ T cells from an HLA-A2+ healthy donor. One week later, the peptides-pulsed autologous PBMCs were used to stimulate the CD8+ T cells for another 3 times at weekly intervals. Then cells the stimulated CD8+ were used as CTLs. The cytotoxicity of CTLs to target cells was detected by lactate dehydrogenase(LDH) release assay and the number of T cells secreting antigen-specific IFN-γ in CTLs was analyzed by enzyme-linked immunospot assay(ELISPOT). RESULTS: The results of morphology observation and FACS indicated that mature DCs were induced from PBMCs. Of the two peptides, peptide L235(FLPDHINIV) induced peptide-specific CD8+ T cells that lysed HLA-A2+ T2 cells pulsed with L235 and OVA66+/HLA-A2+ SW480 cells. Compared with control peptide, L235 increased the number of IFN-γ producing T cells. CONCLUSION: This novel OVA66-derived CTL epitope L235 can induce HLA-A2-restrictive CTL response, which lays the foundation for preparation of tumor-specific peptide vaccine.