Rassenti L Z, Pratt L F, Chen P P, Carson D A, Kipps T J
Department of Medicine, University of California, San Diego, La Jolla 92093-0945.
J Immunol. 1991 Aug 1;147(3):1060-6.
Patients with kappa L chain expressing chronic lymphocytic leukemia (CLL) frequently have leukemia cells reactive with a murine mAb, designated 17.109. Raised against a monoclonal IgM rheumatoid factor autoantibody, this mAb recognizes a major kappa-L chain-associated cross reactive Id, designated 17.109-CRI. Molecular studies reveal that the 17.109-CRI in CLL is a serologic marker for expression of a conserved kappa L chain V region gene (V Kappa gene) of the V Kappa 3 subgroup, designated Humkv325. We isolated an upstream gene fragment of Humkv325 to examine for Ig gene rearrangements of this and other closely related V Kappa 3 genes by Southern analyses. Consistent with Humkv325 encoding the 17.109-CRI, we find that the genomic DNA from all 17.109-reactive leukemia cell populations have gene rearrangements that are detected using this probe. In addition, we observe V Kappa 3 gene rearrangements frequently in the genomic DNA of lambda L chain-expressing leukemia cells. Of the genomic DNA from 33 lambda-L chain-expressing CLL samples, 8 (24%) had additional nongerm-line bands detected with the Humkv325 probe. Consistent with these bands representing Ig gene rearrangements, the additional band in each but one sample also hybridized with probes specific for the J Kappa region and/or the kappa-deleting element. Using the polymerase chain reaction (PCR), we examined the genomic DNA from all lambda L chain-expressing CLL for V Kappa 3 gene rearrangements to J Kappa and/or Kde. PCR on each DNA sample with V Kappa 3 gene rearrangements detected by Southern analysis generated gene fragments that hybridized specifically with oligonucleotides corresponding to framework or CDR of the Humkv325 gene. Nucleic acid sequence analyses of representative samples confirmed that these DNA contained abortive Humkv325 gene rearrangements. PCR for rearranged V Kappa 3 genes in the DNA of other lambda-L chain-expressing CLL either did not generate any PCR product or produced fragments that failed to hybridize with all Humkv325 oligonucleotide probes. Nucleic acid sequence analyses of the latter demonstrated that these represent abortive V Kappa gene rearrangements involving another conserved V Kappa 3 gene, designated Vg. These studies indicate that Humkv325 and Vg frequently may undergo Ig gene rearrangement independent of their expression. As such, the frequent use of Humkv325 in CLL may be secondary, in part, to an enhanced propensity of this V Kappa 3 gene to undergo genetic rearrangement during B cell ontogeny.
表达κ轻链的慢性淋巴细胞白血病（CLL）患者的白血病细胞常常与一种名为17.109的鼠单克隆抗体（mAb）发生反应。该mAb是针对单克隆IgM类风湿因子自身抗体产生的，它识别一种主要的与κ轻链相关的交叉反应性独特型，命名为17.109-CRI。分子研究表明，CLL中的17.109-CRI是Vκ3亚组中一个保守的κ轻链V区基因（Vκ基因）表达的血清学标志物，该基因命名为Humkv325。我们分离了Humkv325的上游基因片段，通过Southern分析检测该基因以及其他密切相关的Vκ3基因的Ig基因重排。与Humkv325编码17.109-CRI一致，我们发现所有与17.109反应的白血病细胞群体的基因组DNA都有使用该探针检测到的基因重排。此外，我们在表达λ轻链的白血病细胞的基因组DNA中也频繁观察到Vκ3基因重排。在33个表达λ轻链的CLL样本的基因组DNA中，有8个（24%）用Humkv325探针检测到额外的非胚系条带。与这些条带代表Ig基因重排一致，除了一个样本外，每个样本中的额外条带也与κ连接区（Jκ）和/或κ缺失元件的特异性探针杂交。我们使用聚合酶链反应（PCR）检测所有表达λ轻链的CLL的基因组DNA中Vκ3基因到Jκ和/或Kde的重排。对每个通过Southern分析检测到有Vκ3基因重排的DNA样本进行PCR，产生的基因片段与对应于Humkv325基因框架或互补决定区（CDR）的寡核苷酸特异性杂交。代表性样本的核酸序列分析证实这些DNA包含不完全的Humkv325基因重排。对其他表达λ轻链的CLL的DNA中重排的Vκ3基因进行PCR，要么没有产生任何PCR产物，要么产生的片段不能与所有Humkv325寡核苷酸探针杂交。对后者的核酸序列分析表明，这些代表涉及另一个保守的Vκ3基因（命名为Vg）的不完全Vκ基因重排。这些研究表明，Humkv325和Vg常常可能独立于其表达而发生Ig基因重排。因此，在CLL中频繁使用Humkv325可能部分是由于该Vκ3基因在B细胞发育过程中发生基因重排的倾向增强所致。
