Morioka N, Kikumoto Y, Hoon D S, Morton D L, Irie R F
John Wayne Cancer Institute, Santa Monica, CA 90404, USA.
Mol Immunol. 1995 Jun;32(8):573-81. doi: 10.1016/0161-5890(95)00020-f.
Recently, we defined the antigenic epitope recognized by the human monoclonal antibody L94 to be a protein with a C-terminal sequence of alanine-proline (AP). An antigenic peptide no. 707 (RVAALARDAP), which was identified by the use of cDNA libraries of an antigen positive melanoma cell line M14, was evaluated for cellular immune responses in melanoma patients. PBMC from 16 of 19 melanoma patients were shown to lyse autologous B lymphoblastoid cell lines (BCL) pulsed with synthetic peptide no. 707 (hereafter no. 707). This specific cytotoxicity to the peptide significantly increased in 84% of melanoma patients after in vivo immunization with a melanoma cell vaccine (MCV). In contrast, peptide specific cytotoxicity was observed in only one of 19 normal volunteer donors. In vitro restimulation of MCV treated patients' PBMC with no. 707 augmented cytotoxicity against autologous no. 707-pulsed BCL. This cytotoxicity was specific to the C-terminal sequence AP, since the removal of C-terminal AP completely abolished the specific lysis. no. 707 restimulation of PBMC enhanced cytotoxicity against autologous melanomas. Autologous melanoma and peptide-pulsed BCL targets were lysed by CD8+CTL in a HLA class I-restricted manner. The strong cytotoxicity was obtained from patients of HLA A24. CTL lysis of autologous no. 707-pulsed BCL was partially blocked by unlabeled autologous melanomas in a cold target inhibition test. This suggested that the epitope identical or cross-reactive to no. 707 may be presented on the melanoma cell surface by HLA class I antigens. Our findings suggest that peptide no. 707 presented on human melanoma cells is recognized by CTL and that C-terminal AP plays a critical role in both antibody and T cell recognition.
最近，我们将人源单克隆抗体L94识别的抗原表位定义为一种C末端序列为丙氨酸 - 脯氨酸（AP）的蛋白质。通过使用抗原阳性黑色素瘤细胞系M14的cDNA文库鉴定出的抗原肽707号（RVAALARDAP），在黑色素瘤患者中进行了细胞免疫反应评估。19例黑色素瘤患者中有16例的外周血单个核细胞（PBMC）显示能裂解用合成肽707号（以下简称707号）脉冲处理的自体B淋巴母细胞系（BCL）。在用黑色素瘤细胞疫苗（MCV）进行体内免疫后，84%的黑色素瘤患者对该肽的特异性细胞毒性显著增加。相比之下，19名正常志愿者供体中只有1人观察到肽特异性细胞毒性。用707号肽对MCV处理患者的PBMC进行体外再刺激，增强了对自体707号脉冲BCL的细胞毒性。这种细胞毒性对C末端序列AP具有特异性，因为去除C末端AP完全消除了特异性裂解。707号肽对PBMC的再刺激增强了对自体黑色素瘤的细胞毒性。自体黑色素瘤和肽脉冲BCL靶细胞被CD8 + CTL以HLA I类限制的方式裂解。来自HLA A24患者的细胞毒性很强。在冷靶抑制试验中，未标记的自体黑色素瘤部分阻断了自体707号脉冲BCL的CTL裂解。这表明与707号肽相同或交叉反应的表位可能由HLA I类抗原呈递在黑色素瘤细胞表面。我们的研究结果表明，人黑色素瘤细胞上呈现的707号肽被CTL识别，并且C末端AP在抗体和T细胞识别中都起着关键作用。
