Hematology, Department of Clinical Medicine and Immunological Sciences, University of Siena and Department of Oncology, Azienda Ospedaliera Universitaria Senese, Siena, Italy.
Blood. 2012 Mar 1;119(9):2106-9. doi: 10.1182/blood-2011-08-375501. Epub 2012 Jan 10.
IGHV1-69/51p1 is expressed by ∼ 30% of unmutated chronic lymphocytic leukemia (U-CLL) and combines with selected IGHD and IGHJ genes generating stereotypes if HCDR3 amino acid homology is > 60%. We had previously revealed stereotypic IGHV1-69/IGHJ6 rearrangements in normal naive B cells, thereby identifying potential counterparts of U-CLL. A different stereotypic IGHV1-69/IGHD3-16(RF2)/IGHJ3 rearrangement carrying the CAR(GGx)YD motif in the N1-region, recurrent in 6% IGHV1-69+ve CLL, is exceptionally sequence restricted, strongly suggestive of shared antigen recognition. We have now analyzed IGHV1-69/IGHJ3 rearrangements in circulating B cells of healthy individuals using several PCR-based approaches with IGHV1-69/IGHJ3 CLL sequences for reference. Stereotypes were found, but all were distinct from CLL. Remarkably, even a highly sensitive semi-nested PCR, specific for the CLL-expressed IGHV1-69/IGHD3-16(RF2)/IGHJ3 stereotype, failed to identify the CAR(GGx)YD sequence, although similar motifs were found. These highly specific B cells are not apparent in the accessible normal repertoire and may expand in response to rarely expressed antigens important in the pathogenesis of CLL.
IGHV1-69/51p1 由约 30%的未突变慢性淋巴细胞白血病 (U-CLL) 表达，如果 HCDR3 氨基酸同源性 > 60%，则与选定的 IGHD 和 IGHJ 基因组合产生刻板印象。我们之前在正常幼稚 B 细胞中揭示了刻板的 IGHV1-69/IGHJ6 重排，从而确定了 U-CLL 的潜在对应物。在 N1 区域中带有 CAR(GGx)YD 基序的不同刻板的 IGHV1-69/IGHD3-16(RF2)/IGHJ3 重排在 6%的 IGHV1-69+ve CLL 中反复出现，序列受限非常强，强烈提示存在共同的抗原识别。我们现在使用几种基于 PCR 的方法，使用 IGHV1-69/IGHJ3 CLL 序列作为参考，分析了健康个体循环 B 细胞中的 IGHV1-69/IGHJ3 重排。发现了刻板印象，但都与 CLL 不同。值得注意的是，即使是针对 CLL 表达的 IGHV1-69/IGHD3-16(RF2)/IGHJ3 刻板印象的高度敏感半巢式 PCR 也未能识别 CAR(GGx)YD 序列，尽管发现了类似的基序。这些高度特异性的 B 细胞在可访问的正常 repertoire 中并不明显，并且可能会在对 CLL 发病机制中重要的罕见表达抗原的反应中扩张。
