Study On The Correlation Of Protein Expression And IgH Gene Rearrangement With The Subgroups Of DLBCL

Background and objectivesDiffuse large B-cell lymphoma (DLBCL) is an aggressive and the most common type of non-Hodgkin's lymphoma, which represents approximately 30% to 59% of these disorders. However, DLBCL is heterogeneous both clinically and morphologically. Despite the use of anthracycline-based chemotherapy, durable remissions are achieved in only 40% to 50% of patients. This indicates that the category may comprise more than one subgroups. During the last decade, some medcine workers has been engaged in it and there were three focuses recently: (l)Does it be of value to subclassify DLBCL on morphological features? (2) Can we utilize the differences of protein expression to determine the subgroups of DLBCL ? (3) Does it possible to subclassify DLBCL on gene expression profile ? Recently, using cDNA microarray technology, DLBCL can be divided into prognostically significant subgroups with germinal center B-cell-like (GCB), activated B-cell-like (ABC), or type 3 gene expression profiles. The GCB group has a significantly better survival than the ABC group, The type 3 group is heterogeneous and not well defined, but has a poor outcome similar to the ABC group. So now we simply devide DLBCL into two groups:GCB and non-GCB. The GCB represents the group with better prognosis, whereas the non-GCB represents the worse. Because this technology is expensive and requires fresh or frozen tissues with adequate amount of RNA, it is hard to be put into use in routine clinical practices. Can we use a more readily available method to subclassify DLBCL? From 2002, attentions were placed on theprognostic value of protein expression and some progresses were achieved. In 2004, using the cDNA microarray results as a golden standard, Hans et al found that the expression of CD 10, bcl-6 and MUM1 can be combined to divide cases of DLBCL into GCB and non-GCB subgroups with an outcome closely related to prognosis. In China, only few studies were mdae on the subclassification of DLBCL by morphologic features. In this study, we had made a retrospective study involving numerous cases of NHL, the cases of DLBCL were reclassified first by morphologic features , then, tissue microarray and immuphotypes and IgH gene rearrangement technology were used to evaluate the feasibility of subclassifition of DLBCL in China and to be expected to provide information for clinical treatment and prognosis assessment.Methods(1) First, 365 cases of NHL from three hospitals in GuangDong between 1999 and 2003 were organized and reclassified according to the new WHO classification of lymphoid neoplasms(2001). 60 cases of DLBCL with overall history were selected and clinicopathologically analysed and reclassified on the basis of morphologic features.(2) By means of tissue microarray and immunohistochemistry technology ,we detected the expression of CD 10, bcl-6 and MUM1 to subdivide the DLBCL cases into GCB and non-GCB groups.(3) Last, IgH clonal gene rearrangement were analysed by PCR from paraffin-embeded sections derived from 60 cases of DLBCL above to verify whether there are differences in different DLBCL subgroups .Results(1) Among the 365 NHL cases, diffuse large B-cell lymphoma is the most common B-cell subtypes and representing 43.3% of all NHL cases .(2) Of the 60 DLBCL cases, the rate of extranodal lymphoma exceeds that of lymph node lymphoma (58.3% vs 41.7%), the most common extranodalsite is gastrointestinal tract(33.3%), the most common nodal site is jugular lympho node(35%). The most common histopathologic morphology of DLBCL is centroblastic which accounts for 88.4% of the 60 cases. (3)Expression of CD10 was seen in 26/60 (43.3%) of the patients, bcl-6 in 28/60 (46.7%), MUM1 in 36/60 (60%). Of the 60 cases, 31(51.7%) were considered GCB and 29(48.3%) were considered non-GCB by TMA analysis.(4)The positive amplication of clonal IgH gene is 31 out of 60 samples(51.7%) for DLBCL. For the GCB group, 17/31 (54.8%) revealed single clonal bands of IgH gene, and for the non-GCB group, 14/29 (48.3%).Conclus...