弥漫性大B细胞淋巴瘤免疫分型与分子遗传学异常的研究

Immunophenotyping and molecular genetic analysis of diffuse large B-cell lymphoma

目的分析弥漫性大B细胞淋巴瘤（diffuse large B-cell lymphoma，DLBCL）的免疫表型分型和分子遗传学异常，并探讨二者之间的相关性及其对于预后的意义。方法用免疫组织化学链霉亲和素一过氧化物酶法检测59例DLBCL患者中CD10、BCL6、MUM1的表达，采用Hans免疫分型法将DLBCL分为生发中心B细胞（germinal center B-cell，GCB）型和非GCB型；分别应用BCL6双色断裂点分离探针、IgH／BCL2双色双融合探针及MYC双色断裂点分离探针在石蜡包埋的淋巴瘤组织切片上进行荧光原位杂交分析，检测BCL6、BCL2和MYC基因的易位和扩增情况。结果在59例DLBCL患者中，GCB型占28．8％（17／59），非GCB型占71．2％（42／59）。BCL6、BCL2和MYC基因易位的发生率分别为24．1％（14／58）、1．7％（1／59）和5．3％（3／57），BCL6、BCL2和MYC基因扩增的发生率分别为17．2％（10／58）、22．0％（13／59）和21．1％（12／57）。BCL6扩增与BCL6易位无相关性（P=0．424），但与BCL2及MYC扩增呈正相关（列联系数C值分别为0．405和0．403，P值均d0．01）。在GCB型中BCL6易位的发生率高于非GCB型，而BCL6、BCL2或MYC扩增更常见于非GCB型，差异接近但均无统计学意义（P值分别为0．089和0．106）。在单因素分析中，免疫分型和国际预后指数积分对总生存率（overallsurvival，OS）均有显著影响（P值分别为0．047和0．001），而BCL6易位和3基因扩增对OS率均无明显影响（P值分别为0．150和0．444）；在多因素分析中，国际预后指数积分是影响OS唯一的独立预后因素（RR=3．843，P=0．017）。结论本组DLBCL患者中GCB亚型较少见，常见的遗传学异常为BCL6易位和BCL6、BCL2及Myc扩增，且3基因扩增之间密切相关，而BCL2易位的发生率低。免疫表型分型对预后的预测意义较小，遗传学异常不能用于预测DLBCL患者的预后。

Objective To perform immunophenotyping and molecular genetic analysis for diffuse large B-cell lymphoma （DLBCL）, and to explore their correlation and implication for prognosis. Methods Immunohistoehemieal streptavidin peroxidase （SP） method was used to determine the expression of CD10, BCL6 and MUM1 in 59 eases of DLBCL. A Hans algorithm was used to classify DLBCL into germinal center B-cell （GCB） and non-GCB subtypes. Interphase fluorescence in situ hybridization （FISH） assay was performed on paraffin-embedded lymphoma tissue sections to detect transloeations and amplifications of BCL6 , BCL2 and MYC genes with dual-color break-apart BCL6 probe, dual-color dual-fusion IgH/BCL2 probe and dual-color break-apart MYC probe, respectively. Results In the 59 eases of DLBCL, 28. 8% （17/59） belonged to GCB subtype, and 71.2% （42/59） belonged to non-GCB subtype. The incidences of BCL6 , BCL2 and MYC gene translocations were 24. 1% （14/58）, 1. 7% （1/59） and 5. 3% （3/57）, respectively. The incidences of BCL6 , BCL2 and MYC gene amplifications were 17.2% （10/58）, 22.0% （13/59） and 21.1% （12/57）, respectively. BCL6 amplification was not correlated with BCL6 transloeation （P=0. 424）, but was correlated with amplifications of BCL2 and MYC （C=0. 405 and 0. 403, respectively, P%0.01）. The incidence of BCL6 translocation in GCB type was higher than that in non-GCB type, and amplifications of BCL6 , BCL2 or MYC were more frequently encountered in non-GCB type, though no statistical significance was detected （P = 0. 089 and 0. 106, respectively）. By univariate analysis, immunophenotyping and international prognostic index （IPI） exerted a significant effect on overall survival （OS） （P=0. 047 and 0. 001, respectively）, but to whichBCL6 translocation and amplification of the 3 genes were not related （P= 0. 150 and 0. 444, respectively）. By multivariate analysis, IPI score was the only independent prognostic factor for OS （RR = 3. 843, P=0. 017）. Conclusion The GCB subtype of DLBCL is less common in the patient cohort. Common genetic aberrations include BCL6 translocation and BCL6 , BCL2 and MYC amplifications. Amplification of the 3 genes is strongly correlated with each other, and the incidence of BCL2 translocation is low. Immunophenotyping only has minor significance for the prognosis. Genetic aberrations cannot predict the clinical outcome of DLBCL.