Differential B-lymphocyte regulation by CD40 and its viral mimic,latent membrane protein 1

Summary: CD40 plays a vital role in humoral immunity, via its potent and multifaceted function as an activating receptor of various immune cells, most notably B lymphocytes. The Epstein-Barr virus-encoded transforming protein latent membrane protein 1 (LMP1) serves as a functional mimic of CD40 signals to B cells but lacks key regulatory controls that restrain CD40 signaling. This allows LMP1 to activate B cells in an abnormal manner that can contribute to the pathogenesis of human B-cell lymphoma and autoimmune disease. This review focuses upon a comparative analysis of CD40 versus LMP1 functions and mechanisms of action in B lymphocytes, discussing how this comparison can provide valuable information on both how CD40 signaling is normally regulated and how LMP1 disrupts the normal CD40 pathways, which can provide information of value to therapeutic design.     

流式细胞术在抗原异常表达淋巴瘤/白血病诊断中的应用

目的 探讨流式细胞免疫分型在抗原异常表达淋巴瘤诊断及鉴别诊断中的作用。方法 应用流式细胞术对伴有抗原异常表达的淋巴瘤3例,B淋巴细胞性白血病8例,T淋巴细胞性白血病1例及伴有淋巴细胞分化抗原表达的急性非淋巴细胞白血病17例,急性粒细胞白血病累及淋巴结1例的免疫表型进行回顾性分析,每例均作胞质CD3ε、CD79a、髓过氧化物酶(MP0)的En Vision两步法染色。结果 11例B细胞淋巴瘤／白血病胞质CD79a阳性,胞质CD3ε及MP0阴性,其中5例伴CD5表达,2例同时伴CD5及1-2项髓系分化抗原表达;1例T淋巴细胞白血病胞质CD3ε阳性,胞质CD79a及MP0阴性,伴CD13、CD33表达;18例急性非淋巴细胞白血病(包括1例急性粒细胞白血病累及淋巴结)胞质髓过氧化物酶(MP0)均阳性,胞质CD3ε及C1979a均阴性,其中8例(包括1例急性粒细胞白血病累及淋巴结)伴T细胞分化抗原表达,8例伴B细胞分化抗原表达,2例同时伴T细胞及B细胞分化抗原表达。结论流式细胞免疫分型不仅能发现淋巴瘤／白血病抗原异常的表达,而且可通过表面免疫标记及胞质CD3s、CD79a、MP0的表达来确定抗原异常表达淋巴瘤／白血病的细胞来源,对抗原异常表达淋巴瘤／白血病的诊断及鉴别诊断具有十分重要价值。     

Co-expression of CD79a (JCB117) and CD3 by lymphoblastic lymphoma

Acute lymphoblastic leukaemia/lymphoma is a malignant disorder derived from the clonal proliferation of lymphoid precursor cells. Whether the tumour cells are of B- or T-cell type is an important criterion for prognosis which has not been available previously to pathologists, due to the lack of a reliable early B-cell marker functioning on routinely processed material. This has changed with the production of monoclonal antibodies against the B-cell signalling molecule CD79a. CD79a is expressed on normal and neoplastic B cells from the early stages of B-cell maturation and has been considered to be B-cell-specific. Currently available antibodies against CD79a, in particular JCB117, allow the identification of B cells, and hence B lymphoblastic disease, in paraffin-embedded material. In this study, the expression of CD79a (JCB117) and CD3 has been investigated in 149 cases of T and 68 cases of B lymphoblastic leukaemia/ lymphoma. For the first time, co-expression of CD79a (JCB117) and CD3 is reported in 10 per cent of cases of T lymphoblastic leukaemia/lymphoma. This finding raises questions about the co-expression of T- and B-cell markers in the development of lymphocytes, benign as well as malignant, and alerts pathologists to a potential problem in diagnosis. Copyright © 1998 John Wiley & Sons, Ltd.     

Cellular origin of human B-cell neoplasms and Hodgkin's disease based on analysis of somatic hypermutations in the immunoglobulin variable region genes

In response to antigen stimulation, B cells undergo a germinal center(GC) reaction such as somatic hypermutations of the immunoglobulin variable region genes, which results in the production and selection of antigen-specific antibodies with increased affinity. Therefore, somatic hypermutations are considered to be a hallmark of GC B cells and their descendants. Pre-GC B cells(precursor B cells, immature B cells, naive B cells and CD5+ B cells) carry no somatic hypermutations, whereas GC B cells and post-GC B cells(memory B cells and plasma cells) express somatic hypermutations. This phenomenon is useful in identifying the cellular origin of various B-cell neoplasms. Precursor B-lymphoblastic leukemia/lymphoma, mantle cell lymphoma, and most B-CLL originate from pre-GC B cells, and follicular lymphoma, Burkitt's lymphoma, marginal zone B-cell lymphoma, diffuse large B-cell lymphoma and myeloma from GC B cells or post-GC B cells. Nodular lymphocyte-predominant Hodgkin's disease and most classical types of Hodgkin's disease are derived from GC B cells. Most human-B cell neoplasms including Hodgkin's disease are derived from GC B cells or their descendants. Molecular processes that modify the DNA of GC B cells, such as somatic hypermutation, class switching and receptor editing occur in the environment of the GCs, and increase the risk of malignant transformation.     

Hodgkin's and non-Hodgkin's lymphoma: spectrum of morphologic and immunophenotypic overlap.

Immunoperoxidase markers are useful and often essential in distinguishing among lymphocyte-predominant Hodgkin's lymphoma, T-cell-rich B-cell lymphoma, and lymphocyte-rich classic Hodgkin's lymphoma. However, it is becoming increasingly clear that these "entities" are closely related clonal B-lineage neoplasms that may intertransform and/or coexist. We hypothesized that, just as there are cases with morphologic overlap, there would also be immunophenotypic overlap that would be found when a series of such cases is studied in detail. Eight cases of lymphocyte predominant Hodgkin's lymphoma, eight cases of lymphocyte-rich classic Hodgkin's lymphoma, seven cases of T-cell-rich B-cell lymphoma, and four cases of large B-cell lymphoma with focal features of T-cell-rich B-cell lymphoma were examined by the immunoperoxidase technique for expression of CD3, CD15, CD30, CD20, CD57, epithelial membrane antigen, and Epstein-Barr virus latent membrane protein (EBV LMP). All eight of the lymphocyte-predominant Hodgkin's lymphoma cases had CD20+ lymphocytic and histiocytic cells and CD57+ rosettes; however, in two cases, occasional lymphocytic and histiocytic cells were also weakly positive for CD15, CD30, and EBV LMP. Among the eight lymphocyte-rich classic Hodgkin's lymphoma cases, CD15+ Reed-Sternberg (R-S) cells were found in seven; however, in three of these cases rare rosettes of CD57+ cells surrounded the R-S or lacunar cells. In one case of large B-cell lymphoma the malignant cells resembled R-S cells and were CD20+, EBV LMP+, CD30+, CD15-, and surrounded by rosettes of CD57+ T cells. The majority of the cases exhibited the "expected" immunophenotypic patterns; however, the exceptional cases that were found serve to confirm the interrelationship among these clonal B-lineage neoplasms.     

Anaplastic lymphoma kinase-positive diffuse large B-cell lymphoma presenting as an isolated nasopharyngeal mass: a case report and review of literature

Anaplastic lymphoma kinase (ALK)-positive diffuse large B-cell lymphoma is a rare and distinct variant of diffuse large B-cell lymphoma with characteristic morphologic, immunophenotypic, and cytogenetic features. We report a case of ALK-positive diffuse large B-cell lymphoma in a 44-year-old male with progressively worsening unilateral nasal congestion and obstruction secondary to a nasopharyngeal mass. Radiologically, the mass was showed to extend to orophanrynx from nasopharynx. Histologically, the tumor cells exhibited plasmablastic morphology with expression of Bob-1, CD4, CD10, CD45, CD56, CD138, EMA, MUM1, Oct-2, and kappa immunoglobulin light chain, but negative for CD20, CD30, CD79a, PAX-5, and lambda. More importantly, the neoplastic cells showed positive immunoreactivity for ALK with exclusive cytoplasmic granular staining pattern. This case represented the second reported ALK-positive diffuse large B-cell lymphoma in the nasopharyngeal region.     

Syndromes mononucléosiques et pathologies hématologiques liés au virus d'Epstein-Barr

The Epstein-Barr virus (EBV), which preferentially infects B cells, persists in the infected subject as a latent asymptomatic infection. In adolescents, infectious mononucleosis is the symptomatic manifestation of primary EBV infection. The viral latency in the memory B-cells, the reservoir cells in peripheral blood in individuals is controlled by CD4 and CD8 positive T-cells. Immunodeficient patients are at high risk of developing EBV driven B-cell lymphomas as the consequence of the expression of oncogenic latency proteins LMP1 and EBNA2. These proteins expressed in infected B cells identify latency III or proliferation program in virus transformed B-cell, leading to lymphoid proliferation. In addition to immunodeficiency-related lymphomas, the most frequent lymphoid malignancies associated with EBV are the endemic Burkitt lymphoma, Hodgkin lymphoma and nasal type T-cell lymphoma.     

BOB.1, CD79a and cyclin E are the most appropriate markers to discriminate classical Hodgkin’s lymphoma from primary mediastinal large B‐cell lymphoma

Hoeller S, Zihler D, Zlobec I, Obermann EC, Pileri SA, Dirnhofer S & Tzankov A
(2010) Histopathology 56, 217–228 BOB.1, CD79a and cyclin E are the most appropriate markers to discriminate classical Hodgkin’s lymphoma from primary mediastinal large B‐cell lymphoma Aims: To clarify which immunohistochemical markers could be helpful in distinguishing between classical Hodgkin’s lymphoma (cHL) and primary mediastinal B‐cell lymphoma (PMBCL) to more narrowly define ‘B‐cell lymphoma, unclassifiable, with features intermediate between diffuse large B‐cell lymphoma and cHL’. Methods and results: Two hundred and 83 cHLs and 51 PMBCLs were analysed on validated tissue microarray platforms with antibodies to BOB.1, CD15, CD20, CD23, CD30, CD79a, cyclin E, LMP‐1, MUM1p, p63 and Oct2. The marker cut‐off scores were calculated using receiver–operating characteristic curves. Markers with the highest positive predictive value for cHL were: CD15, cyclin E, LMP‐1 (all 100%), MUM1p (93%) and CD30 (83%). High sensitivity was achieved only by CD30 (92%) and cyclin E (79%). Nineteen percent of PMBCLs were also positive for CD30, which led to a lower specificity of CD30 as regards cHL (81%) compared with cyclin E (100%). The antibodies with the highest positive predictive value for PMBCL were: CD23 (98%), p63 (96%), BOB.1 (94%) and CD79a (90%), with high sensitivity for BOB.1 (100%), CD79a (89%) and p63 (82%). Conclusions: The use of at least three of the most accurate immunohistochemical markers, cyclin E, CD79a and BOB.1, may be helpful in the differential diagnosis of cHL and PMBCL.     

Oct2蛋白在淋巴瘤中的表达及意义

目的通过检测淋巴瘤中Oct2蛋白的表达,观察其特异性和敏感性,探讨Oct2在淋巴瘤诊断和分类中的意义. 方法应用免疫组织化学EnVision法检测并观察129例不同类型淋巴瘤和10例淋巴结反应性增生(RLH)中的Oct2蛋白表达.结果 RLH中Oct2主要表达在生发中心细胞,而B细胞淋巴瘤则为弥漫阳性表达.Oct2阳性率在B细胞淋巴瘤为97.7%(85/87),与CD20阳性率90.8%(79/87)相比差异无统计学意义(P>0.05);与CD79α阳性率84.7%(61/72)相比差异有统计学意义(P<0.05).Oct2阳性率在T细胞淋巴瘤为3.8%(1/26);在结节性淋巴细胞为主型霍奇金淋巴瘤(NLPHL)和经典型霍奇金淋巴瘤(CHL)分别为3例均阳性和46.2%(6/13),后两组间比较P>0.05.结论作为B细胞淋巴瘤一种新的相对特异而敏感的标记物,Oct2抗体可能有助于淋巴瘤的诊断和分类,可作为诊断B细胞淋巴瘤的首选标记物之一.     

Primary cutaneous large B-cell lymphoma of the leg: histogenetic analysis of a controversial clinicopathologic entity

This study analyzes the pathologic and molecular features of 5 cases of primary cutaneous large B-cell lymphoma of the leg (PCLBCL-leg), recently included in the European Organization for Research and Treatment of Cancer (EORTC) classification of primary cutaneous lymphoma. PCLBCL-leg accounts for 5% to 10% of all primary cutaneous B-cell lymphoma (PCBCL), usually affects elderly patients and carries a worse prognosis than other forms of PCBCL. It has been proposed that the malignant cells of PCLBCL-leg originate from germinal center (GC)-related cells, but their effective normal counterpart is unclear, and the rationale behind the inclusion of this lymphoma as a separate entity is based on its prognosis rather than on its proved histogenesis. All of our cases of PCLBCL-leg morphologically resembled diffuse large B-cell lymphoma (DLBCL), but to better define their histogenesis, we also analyzed various phenotypic and genotypic markers, including mutations of the Ig and of BCL-6 genes, as well as expression of the bcl-6, MUM1, and CD138/syndecan-1 proteins. Immunohistochemically, all of our cases stained for the L-26/CD20cy and CD79a antigens and expressed the bcl-2, bcl-6, and MUM-1 proteins but were negative for both the CD10/CALLA and CD138 antigens. With respect to molecular analysis, the lymphoma population of all PCLBCL-leg carried hypermutation of Ig genes, and all but 1 case also harbored mutations of the BCL-6 gene. Our results indicate that PCLBCL-leg are similar both under the morphofunctional and molecular profiles to most DLBCL of other sites. Thus, caution seems justified before definitely considering PCLBCL of the leg as a distinct entity.     

The Leukocyte Semaphorin CD100 Is Expressed in Most T-Cell, but Few B-Cell, Non-Hodgkin’s Lymphomas

The 150-kd transmembrane protein CD100 is the first semaphorin protein shown to be expressed in lymphoid tissue. CD100 is present in the interfollicular T cell zones and is also expressed by B cells in the germinal centers of secondary lymphoid follicles, but not in the mantle zones. The CD100 molecule was recently cloned, and CD100 transfectants were shown to induce homotypic aggregation of human B cells and improve their viability in vitro, suggesting that CD100 may play a role in lymphocyte aggregation and germinal center formation. We studied the expression of CD100 in 138 clinical cases representing a range of lymphoproliferative disorders, to determine whether this molecule is expressed in these neoplastic processes. In general, we found CD100 expression to be common in peripheral T-cell non-Hodgkin’s lymphomas but rare in B-cell non-Hodgkin’s lymphomas. CD100 expression was not detectable in low-grade B-cell non-Hodgkin’s lymphomas, including cases of small lymphocytic lymphoma (18 cases), marginal zone lymphoma (10 cases), and mantle cell lymphoma (10 cases), as might be expected for these neoplasms that are not of follicular center cell origin. Surprisingly, we found that the vast majority of follicular lymphomas (37 of 40 cases) as well as diffuse large-cell lymphomas of B-cell type (35 cases) did not express CD100. The neoplastic cells in 3 of 11 cases of predominantly large-cell-type follicular lymphoma did express CD100. In contrast, all five cases of high-grade, small non-cleaved (Burkitt-like) B-cell lymphoma were immunoreactive for CD100 expression, as were 18 of 20 cases (90%) of malignant T cell neoplasms. Northern blot analysis of CD100 expression correlated with immunohistochemical findings. Absence of expression of CD100 by neoplastic follicular center B cells is a common feature in follicular lymphomas, but expression of CD100 by T cells is maintained in T-cell lymphoproliferative disorders.     

骨髓活检组织淋巴瘤的病理诊断和分型

目的 探讨组织形态改变、免疫组织化学、基因重排在淋巴瘤骨髓侵犯的病理诊断和分型中的作用。材料与方法 对62例甲醛固定、石蜡包埋的骨髓活检组织,分别做了组织学、EnVision法观察和免疫球蛋白重链(IgH)基因和TCRγ基因重排检测。结果 慢性淋巴细胞性白血病／小淋巴细胞淋巴瘤(CLL／SLL)的异型淋巴细胞呈小梁间结节状或散在分布,有时可见假滤泡结构。滤泡型淋巴瘤(FCL)表现为结节性小梁旁或小梁间的浸润,结节内小淋巴样细胞松散聚集。淋巴浆细胞性淋巴瘤(LPL)主要为小梁间弥散浸润,在小而圆的淋巴细胞间可见散在数量不等的浆细胞样淋巴细胞。边缘区淋巴瘤(MZL)则见模糊的或界限不清的小梁间或小梁旁结节,一些细胞胞质透明。套细胞性淋巴瘤(MCL)异型细胞小到中等大小,缺乏副免疫母细胞和假滤泡。毛细胞性淋巴瘤(HCL)瘤细胞胞膜多清晰,胞质丰富透明,常形成荷包蛋样表现。霍奇金病可见大核瘤细胞,核仁明显。T-非霍奇金淋巴瘤(NHL)浸润骨髓主要为小梁间间质性散在或弥漫分布,胞质多透明,核有芋艿样或脑回状改变,DLBL造血细胞间体积大的瘤细胞散在或弥漫分布。CD3对T细胞来源、CD20和CD79对B细胞来源淋巴瘤有鉴别诊断价值,cyclin D1和(SD5阳性对MCL具有诊断性价值,bcl-2和CD10阳性则对FCL具有诊断性意义,而CLL／SLL除了(SD20和CD79阳性外,也可CD5和CD23阳性。HCL的瘤细胞CD25强阳性。CD15、CD30和Fascin也适用于骨髓霍奇金病的诊断。骨髓中CLL／SLL,LPL,MZL及DLBL的IgH重排率(80％、60％、66．7％、70％)及T—NHL的TCRγ重排率(66．7％)较高。结论 综合组织形态改变、免疫组织化学和IgH／TCRγ重排检测,有助于淋巴瘤骨髓侵犯的诊断和分型,有助于发现骨髓中为数不多的淋巴瘤细胞。     

Variable expression of Epstein-Barr virus-induced gene 3 during normal B-cell differentiation and among B-cell lymphomas

Epstein-Barr virus (EBV)-induced gene 3 (EBI3) is expressed by tumour cells in several EBV-associated malignancies. EBI3 was recently found to associate with a novel peptide, p28, to form a new heterodimeric cytokine, called interleukin-27. In this study, we investigated EBI3 and p28 expression in normal human B lymphocytes and in non-EBV-associated B-cell lymphomas. Low levels of EBI3 were detected in purified tonsillar B cells and expression was upregulated upon anti-CD40 or anti-micro stimulation via NF-kappaB activation. In non-neoplastic tissues, EBI3 expression by lymphocytes was largely restricted to a subset of germinal centre (GC) B cells located at the margin of the light zone, in close contact with CD3+ T lymphocytes. Over 50% of EBI3+ GC B cells were engaged in cell proliferation as assessed by Ki67 expression, and 10-30% expressed MUM1, an early marker of plasma cell differentiation expressed by late centrocytes. Many EBI3+ GC B cells had downregulated bcl-6 expression, which further suggests that these cells correspond to late CD40-activated centrocytes. Immunohistochemical analysis of 64 B-cell lymphomas showed that the highest EBI3 levels were detected in follicular lymphomas and in diffuse large B-cell lymphomas of both GC B-cell-like or non-GC B-cell-like types. No or rare p28 expression was detected in normal or tumour B cells. This constitutive expression of EBI3 by neoplastic B cells may be involved in lymphomagenesis, and may be a useful marker for lymphoma diagnosis.