Rockman S P
Department of Diagnostic Haematology, Royal Melbourne Hospital, Parkville, Victoria, Australia.
Leukemia. 1997 Jun;11(6):852-62. doi: 10.1038/sj.leu.2400678.
Identification of rearrangements in the immunoglobulin heavy chain (IgH), T cell receptor (TCR) and other genes assists in the classification of hemopoietic disorders. This study reviews a 5 year experience of genotyping as an assessment of clonality in a central referral laboratory. Patients were referred for assessment if abnormal hemopoietic populations were identified and where standard morphology, cytochemistry or immunophenotyping techniques were equivocal and unable to establish the diagnosis. Analysis of the antigen receptor genes (IgH gene and TCR gamma locus) was performed in 230 patients by either Southern blotting or the polymerase chain reaction (PCR). Clonal rearrangements of either loci could be demonstrated in 91/230 patients: 56/161 patients analyzed by Southern blotting and 48/125 analyzed by polymerase chain reaction. A subgroup of patients (n = 88) was analyzed for rearrangement of the immunoglobulin heavy chain gene by both techniques. Discordant results were observed in 18 of these patients (20%). Analysis of the TCR gamma locus in a separate group demonstrated discordant results in eight of 40 patients examined (20%). Clinical outcome could be available in 61 patients (median time: 42 months, range 1-68 months): for those in whom a rearrangement was detected approximately 80% went on to develop a lymphoproliferative disorder although this diagnosis was not able to be made at the time the sample was taken. In a subset of patients (n = 14) who presented with lymphocytosis after bone marrow transplantation (seven) or solid organ transplant (seven), clonal lymphoid populations were demonstrated in approximately 50% of cases. The majority of these cases demonstrated the presence of Epstein-Barr virus (EBV) by PCR. The clonality of EBV infection was assessed by Southern blotting and the significance of these findings are discussed. This study explores the differences between Southern blotting and PCR as applied to the study of antigen receptor rearrangement studies. We conclude that detecting a clonal population is valuable in patients where standard diagnostic techniques are equivocal. However, the inability to detect a clonal population should be treated with caution and interpreted in light of other investigations.
免疫球蛋白重链（IgH）、T细胞受体（TCR）及其他基因重排的鉴定有助于造血系统疾病的分类。本研究回顾了一家中心转诊实验室5年来将基因分型作为克隆性评估手段的经验。若发现异常造血细胞群，且标准形态学、细胞化学或免疫表型分析技术结果不明确、无法确诊时，患者会被转诊进行评估。采用Southern印迹法或聚合酶链反应（PCR）对230例患者的抗原受体基因（IgH基因和TCRγ基因座）进行分析。在91/230例患者中可检测到任一基因座的克隆性重排：161例采用Southern印迹法分析的患者中有56例，125例采用聚合酶链反应分析的患者中有48例。对一个亚组患者（n = 88）同时采用两种技术分析免疫球蛋白重链基因重排。其中18例患者（20%）出现结果不一致。在另一个独立组中，对40例患者的TCRγ基因座进行分析，8例结果不一致（20%）。61例患者有临床转归情况（中位时间：42个月，范围1 - 68个月）：在检测到重排的患者中，约80%随后发展为淋巴增殖性疾病，尽管在采集样本时无法做出该诊断。在一部分患者（n = 14）中，骨髓移植（7例）或实体器官移植（7例）后出现淋巴细胞增多，约50%的病例显示存在克隆性淋巴细胞群。这些病例多数通过PCR检测到EB病毒（EBV）。通过Southern印迹法评估EBV感染的克隆性，并对这些发现的意义进行讨论。本研究探讨了Southern印迹法和PCR在抗原受体重排研究中的差异。我们得出结论，在标准诊断技术结果不明确的患者中，检测到克隆性细胞群很有价值。然而，未检测到克隆性细胞群时应谨慎对待，并结合其他检查结果进行解读。
