Silberstein L E, Jefferies L C, Goldman J, Friedman D, Moore J S, Nowell P C, Roelcke D, Pruzanski W, Roudier J, Silverman G J
Department of Pathology and Laboratory Medicine, University of Pennsylvania, School of Medicine, Philadelphia.
Blood. 1991 Nov 1;78(9):2372-86.
To investigate the molecular basis of the autoimmune response to the related i and I carbohydrate antigens, we studied cold agglutinins (CA) from B-cell clones and from the peripheral circulation of patients with lymphoproliferative syndromes. Sequence analyses of expressed variable region genes indicate that both anti-i and anti-I specificities from B-cell clones from two patients are encoded by the VH4.21 or a very closely related VH4 heavy chain gene, whereas the expressed light chain genes differed. The anti-i-secreting B-cells express unmutated germline-encoded VH4.21 and VKI gene sequences. The VH region gene encoding anti-I has the closest homology (97%) to the VH4.21 germline gene and differs at the protein level by only three amino acids. In contrast, while the VL region gene encoding anti-I is most homologous (96%) to the VKIII, kv328 germline gene, there are seven amino acid differences due to nonrandom replacement mutations, which suggests a role for antigen-mediated selection in the anti-I response of this individual. These studies were extended by a structural survey of 20 additional serum CA using antipeptide antibodies specific for determinants in VH and VL regions. All anti-I and anti-i CA were shown to express VH4 heavy chains, and 14 of 17 CA expressed a previously described VH4 second hypervariable region determinant, termed VH4-HV2a. We also found that 13 of 14 anti-I CA used VKIII light chains, while the anti-i CA used light chains from at least three VL families. Taken together, the data show that anti-i and anti-I CA probably both derive from the VH4.21 gene (or a closely related gene). Furthermore, the restricted VH and different VL gene use in anti-i and anti-I CA may reflect the close structural relationship of the i and I antigens.
为了研究针对相关的i和I碳水化合物抗原的自身免疫反应的分子基础，我们研究了来自B细胞克隆以及淋巴增殖综合征患者外周血循环中的冷凝集素（CA）。对表达的可变区基因进行序列分析表明，两名患者B细胞克隆中的抗i和抗I特异性均由VH4.21或与之非常密切相关的VH4重链基因编码，而表达的轻链基因则有所不同。分泌抗i的B细胞表达未突变的种系编码VH4.21和VκI基因序列。编码抗I的VH区域基因与VH4.21种系基因具有最接近的同源性（97%），在蛋白质水平上仅相差三个氨基酸。相比之下，虽然编码抗I的VL区域基因与VκIII、κv328种系基因最同源（96%），但由于非随机置换突变存在七个氨基酸差异，这表明抗原介导的选择在该个体的抗I反应中起作用。通过使用针对VH和VL区域决定簇的抗肽抗体对另外20份血清CA进行结构研究，扩展了这些研究。所有抗I和抗i CA均显示表达VH4重链，17份CA中有14份表达了先前描述的VH4第二高变区决定簇，称为VH4-HV2a。我们还发现，14份抗I CA中有13份使用VκIII轻链，而抗i CA使用来自至少三个VL家族的轻链。综上所述，数据表明抗i和抗I CA可能都源自VH4.21基因（或密切相关的基因）。此外，抗i和抗I CA中VH的限制性使用和不同的VL基因使用可能反映了i和I抗原的密切结构关系。
