Department of Pathology, Faculty of Medicine, Universiti Kebangsaan Malaysia Medical Centre, Kuala Lumpur, Malaysia.
Pathology. 2012 Apr;44(3):228-33. doi: 10.1097/PAT.0b013e3283513fb2.
The hallmark of follicular lymphoma is the t(14;18)(q32;q21) chromosomal translocations that lead to deregulation of BCL2 expression in tumour cells. However, not all cases of follicular lymphoma express BCL2, nor is the t(14;18) translocation always present. Follicular lymphomas lacking the BCL2 rearrangement are less well studied with regards to their immunohistochemical and molecular features. This study aims to investigate the BCL2 protein expression pattern in t(14;18) negative follicular lymphomas.
BCL2 protein expression pattern was analysed in 26 cases of t(14;18) negative follicular lymphoma [determined by fluorescence in situ hybridisation (FISH)], using antibodies against two-different epitopes, i.e., the widely-used antibody BCL2/124 and an alternative antibody E17.
Two of the t(14;18) negative cases showed evidence of BCL2 amplification and trisomy 18. A total of 13 cases (50%) lacked BCL2 expression. In 10 cases (38%) the expression was heterogeneous and in only three cases (12%) the BCL2 expression was strongly positive. These cases could thus be subdivided into three subgroups: Group I, normal BCL2 genes (i.e., no evidence of translocation or amplification), and BCL2 protein negative; Group II, normal BCL2 genes but BCL2 protein positive; and Group III, presence of other genetic alterations, i.e., BCL2 amplification and trisomy 18, and BCL2 protein positive.
This study suggests that it may be possible on the basis of staining to predict that the t(14;18) translocation is absent if a case is either negative for BCL2 protein with different antibodies or has heterogeneous BCL2 expression, possibly acquired through a physiological process of differentiation.
滤泡性淋巴瘤的标志是 t(14;18)(q32;q21)染色体易位，导致肿瘤细胞中 BCL2 表达失控。然而，并非所有滤泡性淋巴瘤病例都表达 BCL2，也并非所有病例都存在 t(14;18)易位。缺乏 BCL2 重排的滤泡性淋巴瘤在其免疫组织化学和分子特征方面的研究较少。本研究旨在探讨 t(14;18)阴性滤泡性淋巴瘤中 BCL2 蛋白的表达模式。
使用针对两个不同表位的抗体，即广泛使用的抗体 BCL2/124 和替代抗体 E17，分析 26 例 t(14;18)阴性滤泡性淋巴瘤[通过荧光原位杂交 (FISH)确定]中 BCL2 蛋白的表达模式。
有 2 例 t(14;18)阴性病例显示 BCL2 扩增和 18 三体证据。共有 13 例(50%)缺乏 BCL2 表达。在 10 例(38%)中表达呈异质性，只有 3 例(12%)的 BCL2 表达呈强阳性。这些病例因此可以分为三个亚组：第 I 组，正常 BCL2 基因(即无易位或扩增证据)，BCL2 蛋白阴性；第 II 组，正常 BCL2 基因但 BCL2 蛋白阳性；第 III 组，存在其他遗传改变，即 BCL2 扩增和 18 三体，以及 BCL2 蛋白阳性。
这项研究表明，如果病例的 BCL2 蛋白染色呈阴性或呈异质性表达，即使用不同的抗体，或者存在其他遗传改变，如 BCL2 扩增和 18 三体，并且 BCL2 蛋白阳性，则可能基于染色来预测 t(14;18)易位不存在。
