Han M, Harrison L, Kehn P, Stevenson K, Currier J, Robinson M A
Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, Rockville, MD 20852, USA.
J Immunol. 1999 Jul 1;163(1):301-11.
TCR alpha (TCRA) expression was examined in RNA samples from PBMC and isolated populations of CD4+, CD8+, and DN T cells from 15 healthy individuals. The expressed TCR repertoire was surveyed using spectratype analysis, a technique that displays the distribution of complementarity determining region 3 (CDR3) lengths for each TCRAV gene family. The results revealed the presence of unusual populations of double-negative (DN; CD4-CD8-CD3+) T cells that express invariant or conserved TCRAV4A, AV7, AV19, and AV24 chains. Each of the conserved TCRA families was over-represented in >70% of the individuals studied, and all individuals expressed at least one of the over-represented TCRAV families. Over-represented conserved AV4A or AV7 sequences were also present in CD8+ T cells from most donors. The extent of TCRA sequence conservation is unparalleled. TCRAV4A, AV19, and AV24 sequences were invariant, although AV4A and AV19 transcripts contained N region additions. TCRAV24 transcripts derived from the direct juxtaposition of V and J gene segments. TCRAV7 sequences showed some diversity in two amino acids encoded at junctions of V and J gene segments. Although derivation of DN T cells with conserved TCRA chains is puzzling, the wide-spread expression of these unusual cells suggests an important function.
在来自15名健康个体的外周血单核细胞（PBMC）以及分离出的CD4 +、CD8 +和双阴性（DN；CD4 - CD8 - CD3 +）T细胞群体的RNA样本中检测了TCRα（TCRA）的表达。使用谱型分析技术对表达的TCR库进行了检测，该技术可显示每个TCRAV基因家族互补决定区3（CDR3）长度的分布。结果显示存在表达恒定或保守的TCRAV4A、AV7、AV19和AV24链的异常双阴性（DN）T细胞群体。在超过70%的研究个体中，每个保守的TCRA家族都有过度表达，并且所有个体至少表达一种过度表达的TCRAV家族。在大多数供体的CD8 + T细胞中也存在过度表达的保守AV4A或AV7序列。TCRA序列的保守程度是无与伦比的。TCRAV4A、AV19和AV24序列是恒定的，尽管AV4A和AV19转录本包含N区添加。TCRAV24转录本源自V和J基因片段的直接并列。TCRAV7序列在V和J基因片段连接处编码的两个氨基酸上表现出一些多样性。尽管具有保守TCRA链的DN T细胞的起源令人费解，但这些异常细胞的广泛表达表明其具有重要功能。
