免疫球蛋白重链框架区的抗原九肽诱导特异性细胞毒T细胞增殖  

Proliferation of specific cytotoxic T lymphocytes induced by immunoglobulin heavy chain framework region-derived antigenic nonapeptides

作　　者：刘英[1] 朱平[1] 胡亚美[2] 

机构地区：[1]北京大学第一医院血液科,现在解放军总医院小儿内科100034 [2]首都医科大学附属北京儿童医院

出　　处：《中华医学杂志》2004年第2期97-102,共6页National Medical Journal of China

基　　金：国家自然科学基金 (3 9970 13 1) ;北京市自然科学基金 (70 3 2 0 2 8) ;北京大学人类疾病中心基金 ;北京大学生物医学跨学科基金 ;北京大学肿瘤中心科研基金

摘　　要：目的　探索免疫球蛋白重链可变区 (IgHV)是否存在T细胞识别的表位。 方法　PCR扩增 10 8例急性淋巴细胞白血病 (ALL)的 7个IgHV家族的重排基因 ,PCR产物直接测序并翻译成氨基酸。利用互联网生物信息资源分析B ALLIgHV基因的重排类型和基因变异 ,利用SYFPEITHI和BIMAS软件预测IgHV基因编码蛋白质的T细胞表位。合成代表性九肽IgHV1家族的QLVQSGAEV ,进行T2结合分析、合成九肽诱导的T细胞扩增、扩增细胞的HLA A 0 2 0 1/QLVQSGAEV四聚体检测等实验 ,确定合成九肽的免疫原性。结果　 6 6 %的B ALL检测到IgHV基因重排克隆。在 4 0份测序得到的B ALLIgHV序列中 ,选出 2 6份进行HLA A 0 2 0 1分子结合九肽的预测 ,发现 7个IgHV家族共有 12条抗原九肽。除 1条位于第 3互补决定区 (CDR3)外 ,10条(83% )位于框架区 (FR) ,并与相应胚系VH 家族的代表序列相同 ;为同一IgHV家族的白血病细胞所共有。合成的IgHV1抗原九肽可将T2细胞表面HLA A 0 2 0 1分子的表达提高 1 6 3倍。HLA A 0 2 0 1正常供者的外周血淋巴细胞接受该九肽负荷的自身PBMC的 1轮刺激 ,CD8+ 四聚体 + 细胞达1 6 4 % ,继续接受该九肽负荷的T2细胞的 2轮刺激 ,CD8+ 四聚体+ 细胞增至 82 5 7%。Objective To identify that immunoglobulin heavy chain framework regions-derived peptides function as cytotoxic T lymphocytes epitopes. Methods Seven IgHV gene families were respectively amplified by PCR and directly sequenced for 108 acute lymphoblastic leukemia cases. Sequences available were translated into amino acid sequences. Bioinformatics were applied for analyzing recombination patterns and gene mutations of the IgHV genes. Softwares SYFPEITHI and BIMAS were used for predicting the T cell epitopes in the immunoglobulin heavy chain variable regions. To determine whether the predicted peptides have immunogenicity, a IgHV1 family nonapeptide QLVQSGAEV was synthesized as a representation and T2 binding assay of this peptide was performed, inducing proliferation of T cells from normal HLA-A*0201 peripheral blood lymphocytes (PBLs) with QLVQSGAEV-loaded antigen presenting cells, and detecting the proliferating T cells by HLA-A*0201/QLVQSGAEV tetramers. Results Complete IgHV gene rearrangements were identified in 66% cases. Among 40 B-ALL IgHV sequences available, 26 were predicted for antigenic nonapeptides that are likely to bind to HLA-A*0201 molecule. Twelve peptides were acquired. Except one peptide derived from CDR3, 10 (83%) peptides were located in the immunoglobulin heavy chain framework regions. Moreover B-ALL belonging to the same IgHV family shared 1～2 peptides. Synthesized peptide QLVQSGAEV up-regulated HLA-A*0201 expression 1.63 times on T2 cell surface. PBLs from a normal HLA-A*0201 donor were stimulated with QLVQSGAEV-loaded autologous PBMCs and T2, the CD8^+ tetramer^+ cells in gated lymphocyte population increased from 1.64% after the first stimulation to 82.57% after the third stimulation. Conclusion Immunoglobulin heavy chain framework region genes encode IgHV family-specific peptides recognized by CTLs. Specific CTLs remain in human peripheral T cell repertoire. Immunoglobulin heavy chain framework-derived peptides function as T cell epitopes to induce the proliferation of specific CT

关 键 词：免疫球蛋白 抗原 诱导 特异性细胞毒T细胞 细胞增殖 急性B淋巴细胞白血病 

分 类 号：R733.7[医药卫生—肿瘤]