Singh A K, Gangemi R M, Barrett K J
Department of Medicine (Nephrology), New England Medical Center, Boston, MA 02111.
Autoimmunity. 1994;18(1):65-75. doi: 10.3109/08916939409014681.
To investigate the structural contribution of the light chain of anti-DNA antibodies to fine specificity, the VKappa genes of two monoclonal anti-DNA antibodies, termed H241 and H102, were cloned and sequenced. H102 and H241 are independently derived from MRL-lpr/lpr mice and differ in their fine specificity: H241 binds dsDNA and normal glomeruli in vitro and deposits in the kidney in vivo, whereas H102 binds only ssDNA and does not deposit in the kidney. Both are encoded by nearly identical VH genes but different N and D regions. Our previous results have demonstrated that the VH gene for H102 and H241 encodes eight other anti-DNA antibodies that also differed in fine specificity. This suggested that the gene product encoded by the VH 102/241 gene, may have intrinsic affinity for DNA, but is unlikely to determine fine specificity or nephritogenicity. In the present study we examined whether the VKappa gene might account for the difference in nephritogenicity. The complete nucleotide and deduced amino acid sequence of VK 102 and VK241 revealed that they are very dissimilar to each other (< 60% homology). VK 241 defined a new member of the VKappa gene family and was moderately homologous to two other VK genes encoding anti-DNA antibodies and to one VK gene encoding an anti-histone antibody all from lupus strains of mice. In addition, sequence diversity in the VK CDR1 region and position 96 of the CDR3 region was observed that may be of significance in determining fine specificity. VK 102 was highly homologous to two other VKappa genes, VKs17.2 and VK C8.5, both encoding anti-DNA antibodies and members of the VK20 gene family. It was striking that all three members of the VK 20 gene family code for DNA reactivity. This suggests that certain VKappa genes may also be used to repeatedly code for anti-DNA reactivity.
为了研究抗DNA抗体轻链对精细特异性的结构贡献，克隆并测序了两种单克隆抗DNA抗体（称为H241和H102）的Vκ基因。H102和H241独立来源于MRL-lpr/lpr小鼠，它们的精细特异性不同：H241在体外结合双链DNA和正常肾小球，并在体内沉积于肾脏，而H102仅结合单链DNA，且不在肾脏中沉积。两者均由几乎相同的VH基因编码，但N和D区域不同。我们之前的结果表明，H102和H241的VH基因还编码另外8种抗DNA抗体，它们在精细特异性上也存在差异。这表明VH 102/241基因编码的基因产物可能对DNA具有内在亲和力，但不太可能决定精细特异性或致肾炎性。在本研究中，我们检测了Vκ基因是否可以解释致肾炎性的差异。VK 102和VK241的完整核苷酸和推导氨基酸序列显示它们彼此非常不同（同源性<60%）。VK 241定义了Vκ基因家族的一个新成员，与另外两个编码抗DNA抗体的Vκ基因以及一个编码抗组蛋白抗体的Vκ基因具有中度同源性，这些基因均来自狼疮小鼠品系。此外，在Vκ互补决定区1（CDR1）区域和CDR3区域的第96位观察到序列多样性，这可能在决定精细特异性方面具有重要意义。VK 102与另外两个Vκ基因VK s17.2和VK C8.5高度同源，这两个基因均编码抗DNA抗体，且都是VK20基因家族的成员。令人惊讶的是，VK20基因家族的所有三个成员都编码与DNA的反应性。这表明某些Vκ基因也可能被反复用于编码抗DNA反应性。
