MHC CLASS II-RESTRICTED PRESENTATION OF ENDOGENOUSLY SYNTHESIZED ANTIGEN - EPSTEIN - BARR VIRUS-TRANSFORMED B-CELL LINES CAN PRESENT THE VIRAL GLYCOPROTEIN GP340 BY 2 DISTINCT PATHWAYS
MHC CLASS II-RESTRICTED PRESENTATION OF ENDOGENOUSLY SYNTHESIZED ANTIGEN - EPSTEIN - BARR VIRUS-TRANSFORMED B-CELL LINES CAN PRESENT THE VIRAL GLYCOPROTEIN GP340 BY 2 DISTINCT PATHWAYS
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DOI：
10.1093/intimm/5.5.451
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发表时间：
1993-05-01
影响因子：
4.4
通讯作者：
RICKINSON, AB
中科院分区：
文献类型：
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作者：
LEE, SP;WALLACE, LE;RICKINSON, AB
eb病毒（EBV）转化的B淋巴母细胞样细胞系（LCL）通过氯喹敏感的内体途径有效地加工外源抗原，用于MHC ii类限制性呈递。然而，使用针对EBV结构蛋白的MHC ii类限制性T细胞克隆，我们经常观察到在没有添加外源病毒的情况下对自体LCL细胞的显著反应。这种反应通过用阿昔洛韦（ACV）（一种阻断EBV感染的药物）预处理LCL而降低。这表明T细胞识别由LCL细胞自发进入病毒生产周期合成的抗原，并使我们质疑通过何种途径发生MHC ii类内源性合成病毒粒子蛋白的限制性呈递。细胞分选实验，使用病毒包膜糖蛋白gp340作为生产感染细胞的表面标记物，证实刺激活性存在于gp340阳性部分。然而，更仔细的分析显示，这些细胞中的大多数不是生产性感染，而是EBV受体阳性，并已结合释放病毒。我们推断，受体介导的释放病毒进入内体途径是LCL可以在MHC II类分子上呈递内源性合成EBV蛋白的一种途径。为了探究是否存在另一种更直接的处理途径，我们使用重组痘苗病毒载体在acv处理的lcl中从头表达gp340。值得注意的是，这些细胞通过氯喹抗性途径将内源性合成的抗原提交给自身gp340特异性T细胞克隆。在同样的实验中，牛痘介导的gp340信号肽缺失形式的表达不会导致T细胞刺激，这表明这第二种加工途径需要内源性合成抗原进入内质网。
Epstein-Barr virus (EBV) transformed B lymphoblastoid cell lines (LCL) efficiently process exogenous antigens for MHC class II-restricted presentation via the chloroquine-sensitive endosomal pathway. Using MHC class II-restricted T cell clones specific for EBV structural proteins, however, we frequently observed significant responses to autologous LCL cells without the addition of exogenous virus. Such responses were reduced by pre-treating the LCL with acyclovir (ACV), a drug blocking productive EBV infection. This suggested T cell recognition of antigen synthesized by LCL cells spontaneously entering virus productive cycle, and led us to question by what route(s) MHC class II-restricted presentation of endogenously synthesized virion proteins was occurring. Cell sorting experiments, using the viral envelope glycoprotein gp340 as a surface marker of productively-infected cells, confirmed that stimulatory activity lay within the gp340-positive fraction. However, closer analysis revealed that most of these cells were not productively-infected but were EBV receptor-positive and had bound released virus. We infer that receptor-mediated delivery of released virus into the endosomal pathway is one route whereby an LCL can present endogenously synthesized EBV proteins on MHC class II molecules. To ask whether another, more direct, route of processing was possible, we used a recombinant vaccinia viral vector to express gp340 de novo in ACV-treated LCLs. Significantly, these cells presented the endogenously synthesized antigen to autologous gp340-specific T cell clones via a chloroquine-resistant pathway. In the same experiments, vaccinia-mediated expression of a signal peptide-deleted form of gp340 did not lead to T cell stimulation, suggesting that this second route of processing required entry of endogenously synthesized antigen into the endoplasmic reticulum.