Stewart A K, Huang C, Stollar B D, Schwartz R S
Department of Medicine, New England Medical Center Hospital, Boston, Massachusetts.
J Exp Med. 1993 Feb 1;177(2):409-18. doi: 10.1084/jem.177.2.409.
Idiotype (Id) 16/6 marks a variable (V) region structure that occurs frequently in the human immunoglobulin repertoire. The basis of the Id has been traced to a germline heavy chain gene segment, VH18/2 (VH26). To pursue the molecular basis for the frequency of Id 16/6, we have analyzed polymerase chain reaction-generated C mu, C gamma, and VH3 family V gene libraries derived from the circulating and tonsillar B cells of four normal individuals and from the B cells of two patients with active systemic lupus erythematosus (SLE). The frequency of VH18/2 in these libraries was compared with three control VH genes, VH56P1, VH21/28, and VHA57. Plaque lifts from C mu and C gamma VH cDNA libraries were screened with gene-specific oligonucleotide probes. The frequency of VH18/2 ranged from 4 to 10% of JH+ plaques (two of five times that of control VH genes). In four VH3 family-specific libraries derived from rearranged DNA, VH18/2 represented 19-33% of VH3+ plaques. Hybridizing VH18/2 plaques were 98-100% homologous to the germline VH gene; mutations when present were often in framework 3. Extensive variation was seen in the complementarity determining region 3 sequences of these rearranged V genes. The high frequency of VH18/2 expression in the B cell repertoire was confirmed by sequencing randomly picked JH+ plaques. In two patients with active SLE the frequency of use of VH18/2 was not greater than that observed in normal subjects. These results show that VH18/2 is overrepresented in the B cell repertoire of normal subjects and suggest that the immune repertoire may be dominated by relatively few V genes.
独特型（Id）16/6标志着一种在人类免疫球蛋白库中频繁出现的可变（V）区结构。Id的基础已追溯到种系重链基因片段VH18/2（VH26）。为了探究Id 16/6出现频率的分子基础，我们分析了聚合酶链反应产生的Cμ、Cγ和VH3家族V基因文库，这些文库来自四名正常个体的循环和扁桃体B细胞以及两名活动性系统性红斑狼疮（SLE）患者的B细胞。将这些文库中VH18/2的频率与三个对照VH基因VH56P1、VH21/28和VHA57进行比较。用基因特异性寡核苷酸探针筛选Cμ和Cγ VH cDNA文库的噬菌斑。VH18/2的频率在JH +噬菌斑的4%至10%之间（是对照VH基因的两到五倍）。在来自重排DNA的四个VH3家族特异性文库中，VH18/2占VH3 +噬菌斑的19%至33%。与VH18/2杂交的噬菌斑与种系VH基因的同源性为98%至100%；存在突变时，通常在框架3中。在这些重排V基因的互补决定区3序列中观察到广泛的变异。通过对随机挑选的JH +噬菌斑进行测序，证实了VH18/2在B细胞库中的高表达频率。在两名活动性SLE患者中，VH18/2的使用频率并不高于正常受试者。这些结果表明，VH18/2在正常受试者的B细胞库中过度表达，并提示免疫库可能由相对较少的V基因主导。
