CD8^＋T细胞对HIV-1合成表位的免疫主导应答研究

Immunodominance in CD8^＋ T cell responses to HIV-1 synthesized epitopes

目的研究CD8^＋ T细胞对人免疫缺陷病毒1型（HIV-1）表位的免疫主导应答。方法分别采用酶联免疫斑点技术（ELtSPOT）和羧乙基锗倍半氧化物（CFSE）标记流式分析技术，以覆盖HIV-1 Env、Pol、Gag、Vif、Nef、Tat区的701个重叠肽段组成的34个肽段库及其部分单肽段作为刺激表位，对一例感染HIV-1的长期不进展者（LTNP）的外周血单个核细胞（PBMC）中CD8^＋ T细胞的了γ-干扰素（IFN-γ）分泌细胞频率和细胞增殖率进行了测定研究。结果HIV-1 Gag区域肽段诱导产生的CD8^＋ T细胞的IFN-γ分泌细胞频率最高，Nef、Tat、Vif区域依次顺减，Env和Pol区域不能诱导产生显著性应答；在IFN-γ ELISPOT实验中，肽段和相应肽段库刺激产生的结果一致；CD8^＋ T细胞在单肽段刺激下，用ELISPOT技术测定的IFN-γ分泌细胞频率和CFSE标记流式分析技术测定的细胞增殖率显示出较好的相关性。结论CD8^＋ T细胞能特异性识别某些HIV-1抗原表位，诱导出免疫主导应答；当进行HIV-1特异性CD8^＋ T细胞反应增殖测定和免疫主导应答研究时，ELISPOT是值得称道的标准实验，同时，推荐一种新颖的CFSE标记流式分析技术。

Objective To investigate immunodominance in CD8^＋ T cell responses to human immunodeficiency virus type 1 （ HIV-1 ） epitopes. Methods Frequency of Interferon-γ （IFN-γ） secreting cells and the proliferation percentage of CD8^＋ T cells in PBMC from an HIV-l-infected long term nonprogressor （LTNP） were assessed after stimulation with either the 34 pools of 701 overlapping peptides covering the regions of HIV-1 Env, Pol, Gag, Vif, Nef, Tat or some single peptides, by using various assays including enzyme-linked immunospot （ELISPOT） and CFSE Carboxy-fluorescein diacetate, succinimidyl ester （CFSE） labeling and flow cytometry. Results HIV-1 Gag peptides induced the highest frequency of IFN-γ secreting cells, followed by Nef, Tat, and Vif. Meanwhile, Env and Pol failed to induce significant responses. In the IFN-γ ELISPOT assay, stimulation with single peptide and the corresponsive peptide pool generated analogous results. In addition, the frequencies of IFN-γ secreting cells and the proliferation percentage of CD8^＋ T cells detected-ELISPOT and CFSE labeling and flow cytometry were proportional, when single peptides were used for stimulation. Conclusion CD8^＋ T cells can respond to some specific HIV-1 epitopes and induce immunodominant responses. As a complimentary approach to the standard of ELISPOT assay, We recommend a novel CFSE labeling and flow cytometry assay for the examination of immunodominance in studies of HIV-1 specific proliferation percentage of CD8^＋ T cell responses.