胃淋巴增生性疾病IgH基因重排的检测及意义

目的 探讨免疫球蛋白重链（ＩｇＨ）基因单克隆性重排的检测对胃ＭＡＬＴ淋巴瘤的诊断及鉴别诊断价值。方法 应用半巢式聚合酶链反应技术检测石蜡包埋的３１例胃ＭＡＬＴ淋巴瘤、２６例淋巴细胞性胃炎及１１例对照标本免疫球蛋白重锭基因重排的克隆性。引物选用互补于ＩｇＨ基因Ｖ区及Ｊ区保守序更的Ｆｒ２,Ｆｒ３。结果 （１）用Ｆｒ３为引物扩增,７４．２％的胃ＭＡＬＴ淋巴瘤获得单克隆性重条带;联合Ｆｒ２扩增,可使其检出     

Clonal immunoglobulin heavy chain and T-cell receptor γ gene rearrangements in primary gastric lymphoma

AIM:To study the diagnostic value of immunoglobulin heavy chain(IgH)and T-cell receptorγ (TCR-γ)gene monoclonal rearrangements in primary gastric lymphoma(PGL).METHODS:A total of 48 patients with suspected PGL at our hospital were prospectively enrolled in this study from January 2009 to December 2011.The patients were divided into three groups(a PGL group,a gastric linitis plastica group,and a benign gastric ulcer group)based on the pathological results(gastric mucosal specimens obtained by endoscopy or surgery)and follow-up.Endoscopic ultrasonography(EUS)and EUSguided biopsy were performed in all the patients.The tissue specimens were used for histopathological examination and for IgH and TCR-γ gene rearrangement polymerase chain reaction analyses.RESULTS:EUS and EUS-guided biopsy were successfully performed in all 48 patients.In the PGL group(n=21),monoclonal IgH gene rearrangements were detected in 14(66.7%)patients.A positive result for each set of primers was found in 12(57.1%),8(38.1%),and 4(19.0%)cases using FR1/JH,FR2/JH,and FR3/JH primers,respectively.Overall,12(75%)patients with mucosal-associated lymphoid tissue lymphoma(n=16)and 2(40%)patients with diffuse large B-cell lymphoma(n=5)were positive for monoclonal IgH gene rearrangements.No patients in the gastric linitis plastica group(n=17)and only one(10%)patient in the benign gastric ulcer group(n=10)were positive for a monoclonal IgH gene rearrangement.No TCRgene monoclonal rearrangements were detected.The sensitivity of monoclonal IgH gene rearrangements was 66.7%for a PGL diagnosis,and the specificity was96.4%.In the PGL group,8(100%)patients with stage IIE PGL(n=8)and 6(46.1%)patients with stage IE PGL(n=13)were positive for monoclonal IgH gene rearrangements.CONCLUSION:IgH gene rearrangements may be associated with PGL staging and may be useful for the diagnosis of PGL and for differentiating between PGL and gastric linitis plastica.     

t(14;18) chromosomal translocation in follicular lymphoma: an event occurring with almost equal frequency both at the D to JH and at later stages in the rearrangement process of the immunoglobulin heavy chain gene locus

bcl-2/IgH fusion is considered a genetic error which occurs at the diversity (D) to joining (J_H) stage of the gene rearrangement process in the immunoglobulin heavy chain (IgH) gene locus. Translocations of the bcl-2 protooncogene to the IgH locus at ontogenetically later IgH gene rearrangements are thought to represent exceptions. In the present study we analysed the junctional nucleotide sequence of 18 bcl-2/IgH fusion genes identifiable by polymerase chain reaction performed on DNA extracted from diagnostic lymph node tissue of 14 follicular lymphoma patients. In all clones studied, segments of variable length were found interposed between bcl-2 and J_H gene sequences. Nucleotide sequence data analysis and comparisons performed with the corresponding germline sequences using the GenBank/EMBL database revealed the presence of D segments in most of the bcl-2/IgH fusion genes under study (13/18). By the same kind of computer-aided analysis, previously unrecognized D segments were identified in many published junctional sequences. These results suggest that bcl-2/IgH fusion events are very prevalent in rather more differentiated stages in B-cell ontogeny than previously recognized.