非特指性外周T细胞淋巴瘤中EBER、 LMP1的表达及与预后的关系

目的 探讨非特指性外周T细胞淋巴瘤(peripheral T-cell lymphoma,not otherwise specified,PTCL-NOS)中EBER、LMP1的表达及与患者预后的关系.方法 采用原位分子杂交(in situ hybridization,ISH)技术和免疫组化法分别检测81例PTCL-NOS及59例对照组[48例血管免疫母细胞性T细胞淋巴瘤(angioimmunoblastic T-cell lymphoma,AITL)和11例结外NK/T细胞淋巴瘤(extranodal NK/T cell lymphoma,ENK/TCL)]中EBER和LMP1的表达,并分析EBER表达与PTCL-NOS患者临床病理特征及预后的关系.结果 (1)81例PTCL-NOS中,EBER阳性率为43.2％ (35/81);35例EBER阳性的PTCL-NOS病例中免疫组化得分1分+2分者共29例,占EBER阳性病例的82.9％(29/35),3分+4分者共6例,占17.1％ (6/35).EBER表达与PTCL-NOS患者年龄、性别、乳酸脱氢酶(lactate dehydrogenase,LDH)水平及临床分期均无明显相关性(P＞0.05).(2)81例PTCL-NOS组织中,LMP1蛋白阳性率为22.2％(18/81).LMP1蛋白表达与EBER表达具有一致性,但EBER阳性率明显高于LMP1 (P ＜0.05).(3)33例PTCL-NOS获得临床随访资料,随访时间1～63个月,中位生存期为23个月,总生存率为33.3％(11/33).Kaplan-Meier生存曲线分析显示,EBER阳性组的生存率明显低于EBER阴性组(P＜0.05).结论 EB病毒(EBV)感染可能是PTCL-NOS发生、发展中重要但非根本性的因素.EBER-ISH检测EBV感染具有较高的敏感性和特异性.EBV感染对PTCL-NOS患者的预后判断具有重要意义.     

广西口腔颌面颈部原发性淋巴瘤 EBV感染及其临床病理特征分析

目的：探讨广西地区EBV感染与恶性淋巴瘤病理类型及发病的相关性。方法采用原位杂交技术检测81例口腔颌面颈部淋巴瘤的肿瘤组织中EBV编码的RNA(EBER),并分析其临床病理特征。结果(1)EBER总阳性率为44．4%,霍奇金淋巴瘤占检出率的40%,非霍奇金淋巴瘤占检出率的45．1%,不同细胞来源的非霍奇金淋巴瘤依次占检出率的75%( T细胞淋巴瘤)、87．5%( NK/T细胞淋巴瘤)、2．9%( B细胞淋巴瘤),T细胞、NK/T细胞非霍奇金淋巴瘤EBER阳性率比B细胞非霍奇金淋巴瘤高,差异有统计学意义(P<0．05)。(2)淋巴结内、外淋巴瘤EBER阳性率分别为17．9%、58．5%,二者比较差异有显著性(P<0．05)。(3)50岁以上淋巴瘤患者EBER检出率(36．2%)低于50岁以下患者检出率(55．9%),差异无显著性(P>0．05)。结论广西地区口腔颌面颈部淋巴瘤与EBV感染相关,其中以发生在淋巴结外弥散淋巴组织的NK/T细胞淋巴瘤最为显著。     

鼻NK/T细胞淋巴瘤--15年研究报道

目的 :探讨鼻NK/T细胞淋巴瘤 (原诊断为“中线恶性网织细胞增生症”)的临床病理及免疫表型特征、病变性质及其与EB病毒感染的关系。方法 :过去 15年中对近 2 0 0例“中线恶网”病例做了一系列研究 ,包括临床病理分析、LSAB法免疫组化染色作免疫表型分析、用PCR技术作T细胞受体β和γ链基因重排及EBV DNA检测、EBER原位杂交和原位末端标记DNA片段技术检测细胞凋亡。结果 :①鼻NK/T细胞淋巴瘤有特征性临床及病理形态学表现 ;②瘤细胞表达CD3ε:89 8% ;CD45RO :81 2 % ;CD5 6 :81 2 % ;TIA 1:10 0 %。不表达B淋巴细胞和组织细胞分化抗原 ;③TCR β链基因重排检出率为85 7% ,TCR γ链基因重排检出率为 94 45 % ;④EBV DNA检出率为 6 7 86 % ;EBER原位杂交阳性率为 90 6 3% ;⑤肿瘤组织中的凋亡细胞与Ki 6 7 呈明显正相关 (P <0 0 0 6 3) ,Ki 6 7 细胞数量变化与患者的平均生存期有明显关系 (P <0 0 2 )。结论 :“中线恶网”实为EB病毒相关、细胞毒性NK/T细胞淋巴瘤。     

霍奇金淋巴瘤EB病毒感染和p53蛋白表达的关系

目的 :探讨EB病毒在霍奇金淋巴瘤 (HL)潜伏感染和 p5 3蛋白表达的关系。 方法 :应用EBER 1寡核苷酸探针以原位杂交 (ISH)方法检测 72例HL组织中的EBER ;用免疫组化方法检测 p5 3蛋白表达。 结果 :发现HL中R S细胞EBER 1和p5 3蛋白的阳性率分别为 5 3 2 0 %和 47 2 2 %。HL中EBER 1检出率明显高于淋巴结反应性增生组 (P <0 0 5 ) ,同时HL中的R S细胞含有EBV潜伏感染期中高拷贝 (RNA ,EBER 1)含量丰富 ,阳性信号在核仁蛋白膜表达。检测HL淋巴细胞衰减型 p5 3的阳性率较高。结论 :HL发生可能与EB病毒潜伏感染有关。EB病毒、p5 3之间可能存在内在联系并相互影响 ,p5 3蛋白阳性者预后不良。     

鼻咽癌组织中DNA损伤与EB病毒感染的相关性研究

目的分析鼻咽癌(NPC)组织磷酸化组蛋白H2AX(γ-H2AX)的表达水平和EB病毒(EBV)的感染情况,探寻二者的相关性。并用细胞实验进行验证,以阐明EBV诱导DNA损伤应答进而促进NPC发生发展的可能机制。方法选取NPC标本50例和鼻咽炎(NPI)20例,采用免疫组化法检测γ-H2AX及EB病毒潜伏膜蛋白1(LMP1)的表达,对LMP1阴性标本采用原位杂交方法检测EB病毒编码的RNA(EBER);采用Western blot法检测EBV感染鼻咽癌细胞CNE1后γ-H2AX表达的变化。结果NPC组γ-H2AX的阳性率达94%,显著高于NPI组的40%;EBV阳性率为94%,显著高于NPI组的30%;97.9%EBV感染的NPC组织γ-H2AX阳性,二者表达有相关性(P0.05)。通过Western blot法检测进一步验证,EBV感染可使CNE1中γ-H2AX的表达量增高。结论γ-H2AX表达和EB病毒感染有密切关联性,EBV感染可能是通过诱导细胞DNA损伤,造成基因组不稳定从而促进NPC的发生发展。     

非霍奇金淋巴瘤与p53蛋白表达的关系

目的 :探讨非霍奇金淋巴瘤 (NHL)与 p5 3蛋白表达的关系。 方法 :用免疫组化S P法检测 10 2例 (低度恶性 2 3例 ,中度恶性 36例 ,高度恶性 4 3例 )NHLp5 3蛋白表达 ,根据 p5 3蛋白阳性细胞百分率将其表达水平分为 4级 :0级 (阴性 ) ,1级 (1%～ 2 5 % ) ,2级 (2 6 %～ 5 0 % ) ,3级 (>5 0 % )。结果 :低度恶性组 2 0 / 2 3(87% )p5 3表达为 0级 ,中度恶性组 31/ 36 (86 1% )表达为 1级 ,高度恶性组 33/ 4 3(76 7% )表达为 2～ 3级。 2 5例随访 7～ 6 8个月 ,p5 30～ 1级NHL完全缓解率 (CRR ,11/ 14 )高于p5 32～ 3级NHLCRR (1/ 11,P <0 0 1) ,前者生存率 (13/ 14 )高于后者 (3/ 11,P <0 0 1)。NHLp5 3蛋白表达水平与其恶性度密切相关 (P <0 0 1)。结论 :p5 3蛋白表达阳性细胞百分率是判断NHL恶性度、疗效及预后较可靠的参数。肿瘤性p5 3蛋白表达检测对中高度恶性NHL的诊断有参考价值     

不同类型霍奇金淋巴瘤EBV检测的原位杂交和免疫组化方法比较

目的 探讨EBER原位杂交和免疫组化EnVision两步法在检测不同类型霍奇金淋巴瘤(Hodgkin's lymphoma,HL)中EBV的表达和意义.方法 收集68例不同类型HL标本(结节硬化型38例、混合细胞型18例、淋巴细胞丰富型7例、淋巴细胞消减型5例),石蜡切片后,分别采用EBER原位杂交法检测EBV编码的mRNA(epstein barr encoded RNAs1,EBER1)以及免疫组化EnVision两步法检测EBV潜伏膜蛋白1(laten mbmbrane proteins,LMP1)在不同类型HL中的表达.结果 68例标本中,免疫组化EnVision两步法检测结果 总阳性率为36%(25/68),其中结节硬化型为23%(9/38),混合细胞型为66%(12/18),淋巴细胞丰富型和淋巴细胞消减型分别为28%(2/7)和40%(2/5);原位杂交检测结果 总阳性率为55%(38/68),其中结节硬化型为42%(16/38),混合细胞型为88%(16/18),淋巴细胞丰富型和淋巴细胞消减型分别为42%(3/7)和60%(3/5).结论 在对不同类型HL的EBV检测中,EBER原位杂交方法 比免疫组化EnVision两步法检出率更高,定位更清晰,同时也更具特异性和敏感性.     

EB病毒与乳腺癌的相关性

目的：探讨EB病毒( Epstein-Barr virus, EBV)与乳腺癌发生、发展的相关性。方法随机选取不同发展阶段的乳腺病变组织246例,采用聚合酶链反应( polymerase chain reaction, PCR)、原位杂交( in situ hybridization, ISH)、激光捕获显微切割( laser capture microdissection, LCM)、免疫组化染色EnVision法检测EBV DNA、RNA、蛋白质水平,分析EBV与乳腺癌发生、发展的关系。结果免疫组化标记246例乳腺病变均未检测到EBV潜伏膜蛋白LMP1的表达。 PCR法在乳腺癌(12/23)、原位癌(0/10)以及乳腺良性病变(0/15)中检测到EBV DNA,但用地高辛标记的EBV DNA探针对48例乳腺良、恶性病变组织(包括PCR扩增阳性的12例乳腺癌标本)进行ISH检测,在癌细胞、乳腺上皮细胞和间质淋巴细胞内均未检测到阳性杂交信号。采用LCM PCR检测12例PCR扩增阳性和12例阴性乳腺标本的乳腺上皮细胞和间质淋巴细胞,在12例PCR阳性标本的间质细胞中扩增出EBV DNA,癌组织中未检出EBV DNA。用EBV RNA探针和ISH方法在75例乳腺良恶性病变组织中均未检测到EBER表达。结论在该文选择的标本中,乳腺癌发生、发展与EBV感染无关。     

胃黏膜相关淋巴组织型淋巴瘤细胞凋亡和bcl—2、p53蛋白表达

目的 :探讨胃黏膜相关淋巴组织型 (MALT)淋巴瘤中细胞凋亡特点及其与bcl 2、p5 3基因蛋白表达的关系。 方法 :应用TdT酶介导生物素化dUTP缺口末端标记 (TUNEL)技术 ,显示肿瘤凋亡细胞 ,免疫组织化学S P法显示bcl 2、p5 3基因蛋白表达。结果 :低度恶性 ,低高混合恶性 ,以及高度恶性组肿瘤细胞凋亡率平均分别为 (0 2 5± 0 12 ) %、(0 46± 0 2 4) %及 (1 32± 0 35 ) % ;而三组bcl 2阳性率分别为 83%、61 6 %及 43 7%。高度恶性组与低度恶性组bcl 2阳性率及凋亡发生率均差异有显著性 (P <0 0 5 ) ;bcl 2表达与凋亡率呈显著负相关 (P <0 0 5 ) ;86例肿瘤组织中 ,p5 3阳性者 2 7例 (30 % ) ,其中低度恶性组 3例 ,混合恶性组 3例 ,高度恶性组 2 1例。高度恶性组 p5 3阳性率高于其余两组。p5 3表达与bcl 2表达著负相关 (P <0 0 5 )。结论 :在胃MALT淋巴瘤中 ,随着组织学分级的提高 ,凋亡细胞显著增多 ,凋亡在肿瘤发生发展转化中起重要作用。p5 3和bcl 2均为重要的凋亡调控基因 ,在胃MALT淋巴瘤从低度恶性到高度恶性的转化中 ,p5 3和bcl 2基因可能起重要作用。     

CD21非依赖性EB病毒对人胃印戒细胞癌细胞系的感染

目的　探讨CD2 1非依赖性EB病毒 (EBV)对人胃印戒细胞癌细胞系 (HSC 39)的感染作用。方法　用Akata和P3HR 1EBV毒株感染HSC 39,有限稀释法对感染细胞进行克隆。结果　两种EBV毒株感染细胞中均可检测到EBV编码的小RNA(EBER)的表达 ,两种EBV毒株感染的亲代细胞及大多数细胞克隆表达EBV核抗原 (EBNA1) ,但不表达EBNA2、潜伏期膜蛋白 (LMP1)和LMP2A。表现为潜伏Ⅰ型感染。未感染的HSC 39细胞及P3HR 1感染的细胞克隆CD2 1表达阴性 ,而AkataEBV感染的部分细胞克隆CD2 1mRNA阳性。结论　EBV可能通过不依赖CD2 1受体的途径感染HSC 39,印戒细胞癌细胞系可用作EBV感染的靶细胞。     

大细胞间变型T细胞淋巴瘤与EBV关系

目的：研究大细胞间变形Ｔ细胞淋巴瘤（ＡＬＣ－ＴＣＬ）与ＥＢＶ之间的关系，方法：应用免疫组织化学，聚合酶锭反应和ＲＮＡ原位杂交方法检测ＥＢＶ－ＤＮＡ的序列和ＥＢＶ编码ＲＮＡ。结果：检测的７例ＡＬＣ－ＴＣＬ，其中４例显示ＥＢＶ－ＤＮＡ和Ｅ－ＢＥＲ１／２阳性，两种检测方法的阳性率均为５７．１％（４／７），结论：ＡＬＣ－ＴＣＬ的发病与ＥＢＶ的感染的关系较密切。     

CLINICOPATHOLOGICAL,IMMUNOLOGICAL AND GENETIC STUDIES OF CD30+ ANAPLASTIC LARGE CELL LYMPHOMA OF B-CELL TYPE; ASSOCIATION WITH EPSTEIN–BARR VIRUS IN A JAPANESE POPULATION

The clinicopathological features, the immunophenotype, and the presence of Epstein–Barr virus (EBV)-associated genomes and gene products were examined in 17 cases of CD30⁺ anaplastic large cell lymphoma (ALCL) of B-cell type. Microscopically, the 17 cases were divided into ten cases of the monomorphic type and seven cases of the pleomorphic type. EBV was detected in 6 of 17 cases (38 per cent) by RNA in situ hybridization (ISH) with EBV-encoded RNA (EBER1). EBER1⁺ cases consisted of two cases (20 per cent) of the monomorphic type and four cases (57 per cent) of the pleomorphic type. The five EBER1⁺ cases showed clonality of the EBV genome by Southern blotting, consistent with the presence of EBV in a monoclonal proliferation. The EBV-encoded latent membrane protein 1 (LMP1) was found in all six EBER1⁺ cases and EBV-encoded nuclear antigen 2 (EBNA2) was present in two cases by immunohistochemistry. No expression of LMP1 or EBNA2 was observed in the EBER1⁻ cases. The EBER1⁺ cases had a tendency for a more favourable prognosis than the EBER1⁻ cases. It is concluded that EBV has an association with CD30⁺ ALCL of B-cell type in the Japanese population studied, and especially with the large pleomorphic type. EBV infection may play a pathoaetiological role and may influence clinical behaviour.     

Hepatosplenic gammadelta T-cell lymphoma: relation to Epstein-Barr virus and activated cytotoxic molecules

AIMS: Hepatosplenic gammadelta T-cell lymphoma (TCL) is a rare, aggressive subset of peripheral TCL that presents with hepatosplenomegaly and cytopenia. Epstein-Barr virus (EBV) infection and activated cytotoxic molecules (granzyme and perforin) are uncommon in hepatosplenic gammadelta CTL. EBV infection and activated cytotoxic molecules are occasionally detected in non-hepatosplenic gammadelta TCL. We describe the clinicopathological features of three Japanese cases who were not immunodeficient. METHODS AND RESULTS: All cases showed gammadelta T-cell type (CD2+, CD3+, T-cell receptor (TCR)delta-1+, betaF1-). Two cases expressed natural killer (NK) cell-associated antigens (CD8-, CD16+, CD56+; CD8-, CD16-, CD56+), and one expressed CD8 (CD8+, CD16-, CD56-). All cases expressed cytotoxicity-associated molecules (perforin, granzyme B, TIA-1 and Fas ligand). However, perforin and Fas ligand were not detected in one case. In-situ hybridization analysis with EBER probes revealed strong nuclear positivity in all neoplastic cells. In addition, two cases showed clonal bands of the EBV terminal repeat (TR) gene. Cytologically, instead of the presence of monomorphic medium-sized cells, our three cases showed pleomorphic medium-sized and large cells. CONCLUSIONS: Our gammadelta TCL cases were clinicopathologically considered to be compatible with hepatosplenic gammadelta T-cell lymphoma. However, with regard to EBV association, activated cytotoxic profile and cytological features they resembled non-hepatosplenic gammadelta TCL. EBV may play a role in this disease by inducing cellular activation.     

肠道T细胞淋巴瘤中的EB病毒感染和T细胞内抗原1的表达

目的 探讨ＥＢ病毒感染在肠道Ｔ细胞淋巴瘤发病中的意义。方法 用ＥＢＥＲ１／２原位杂交及三步ＡＢＣ法免疫组织化学染色技术,观察２４例肠道Ｔ淋巴瘤患者中ＥＢ病毒感染及Ｑ细胞内抗原（ＴＩＡ－１）抗原表达情况,选用的抗体有ＴＬＡ－１,ＬＭＰ－１,ＣＤ３,ＣＤ２０,ＣＤ３０和ＣＤ４５ＲＯ等。     

T细胞性淋巴瘤组织CD56的检测及其与EB病毒的关系

目的探讨Ｔ细胞性淋巴瘤（ＴＣＬ）中ＣＤ５６的表达情况及ＣＤ５６阳性表达同爱波斯坦－巴尔病毒（ＥｐｓｔｅｉｎＢａｒＶｉｒｕｓ,ＥＢＶ）感染的关系。方法对４６例ＴＣＬ进行ＣＤ５６的免疫组织化学ＬＳＡＢ法检测及ＥＢＥＲｓ的原位杂交检测。结果（１）４６例ＴＣＬ中８例ＣＤ５６阳性（１７．４％）,其中鼻腔、咽部和口腔阳性率最高（５／１７例,２９．４％）。弥漫性大细胞型淋巴瘤ＣＤ５６阳性率最高（６／１６例,３７．５％）。（２）４６例ＴＣＬ中２４例ＥＢＥＲｓ阳性（５２．２％）。（３）８例ＣＤ５６阳性病例中,４例ＥＢＥＲｓ阳性。结论ＣＤ５６的表达同ＴＣＬ发生部位和类型有一定关系。ＣＤ５６阳性表达与ＥＢ病毒感染未发现相关性     

TCL1 expression and Epstein-Barr virus status in pediatric Burkitt lymphoma

Elevated T-cell leukemia-1 (TCL1) oncoprotein expression might promote human Burkitt lymphoma (BL) because increased TCL1 causes Burkitt-like lymphomas in TCL1 transgenic mice. Epstein-Barr virus (EBV) infection has been implicated as a cause of increased TCL1 expression in multiple BL cell lines, suggesting a critical connection between EBV and TCL1-induced BL. The TCL1 expression and EBV status of 14 sporadic pediatric BL cases was determined by immunohistochemical staining for TCL1 and in situ hybridization for EBV-encoded RNA (EBER). Our results showed TCL1 protein in 11 cases, predominantly in the nucleus with strong-intensity staining. EBER was positive in 4 cases, with 3 of these cases also TCL1+. In the 10 cases that were EBER-, TCL1 was strongly positive in 8. These data indicate that the TCL1 oncoprotein is expressed strongly in most pediatric BL cases. However, persistent EBV is not essential for increased TCL1 expression, although elevated TCL1 and c-MYC coexpression might cooperate in the development of most pediatric and adult BL cases.     

High frequency of Epstein–Barr virus in Chinese peripheral T-cell lymphoma

Forty-two cases of Chinese T-cell lymphoma were studied for expression of Epstein–Barr virus (EBV) encoded RNA (EBER-1) and EBV latent membrane protein-1 (LMP-1) using in situ hybridization and immunohistochemistry, respectively. EBV was detected in tumour cells in 24/39 peripheral T-cell lymphomas (62%), comprising 18/27 pleomorphic, medium and large cell lymphomas (67%), 4/6 angioimmunoblastic lymphadenopathy-like lymphomas (67%), 2/2 Lennert's lymphomas, 0/2 anaplastic large cell lymphomas, and 0/2 T-zone lymphomas. EBV was not found in three T-lymphoblastic lymphomas. EBV was associated with 12/24 nodal (50%) compared with 12/15 extranodal (80%) peripheral T-cell lymphomas. In EBV positive nodal lymphomas, 9/12 cases (75%) contained less than 10% EBER positive tumour cells. In EBV positive extranodal lymphomas, 9/11 cases (82%) showed EBV gene expression in more than 50% of the tumour cells, and in five of these almost all tumour cells were positive. Lymphomas of the nasopharynx (mainly midline granuloma-type) showed EBER-1 expression in nearly all tumour cells. LMP-1 was detected in 19/23 EBER positive peripheral T-cell lymphomas (83%). Our results show that EBV is strongly associated with peripheral T-cell lymphomas in Chinese. An important role for the virus is suggested in lymphomas of the nasopharynx. The significance of EBV in T-cell lymphomas that contain only a minor population of virally infected tumour cells is currently unclear.     

Expression of Epstein-Barr virus in Langerhans' cell histiocytosis

Langerhans' cell histiocytosis (LCH) is a proliferative histiocytic disorder of unknown etiology. We previously reported that Epstein-Barr virus (EBV) infects and proliferates in macrophages, and investigated the possibility that EBV exhibits etiologic effects in LCH. To detect EBV expression, paraffin sections from 17 LCH cases were examined by mRNA in situ hybridization for EBV BamHIW, Epstein-Barr virus nuclear antigen-2 (EBNA2), and Epstein-Barr virus-encoded small nonpolyadenylated RNA (EBER1) sequences, and by indirect immunofluorescence staining for EBNA2, latent membrane protein 1 (LMP1), and BamHIZ-coding leftward-reading frame 1 (BZLF1). To detect EBV DNA, polymerase chain reaction (PCR)-Southern blotting was used. All cases showed positive hybridization signals by BamHIW mRNA in situ hybridization. Also, 13 and 14 cases showed positive signals for EBNA2 and EBER1 RNA in situ hybridization, respectively. Furthermore, almost all cases exhibited fluorescence after immunofluorescence staining with monoclonal anti-EBNA2 and anti-BZLF1 antibodies, and 15 cases were positive after treatment with monoclonal anti-LMP1 antibody. PCR-Southern blotting detected an amplified EBER1 sequence in all 9 cases examined. EBV expression was confirmed in LCH using in situ hybridization and immunofluorescence. Furthermore, EBV DNA was also detected by PCR-Southern blotting. These positive results of BZLF1 suggest that EBV replicates in LCH tissues.     

Detection of latent Epstein-Barr virus (EBV) DNA in paraffin sections of nasopharyngeal carcinomas expressing no EBV-encoded small RNAs using in situ PCR

Summary.  In situ hybridization (ISH) with EBER 1 (Epstein-Barrvirus (EBV)-encoded small RNA1) probes is widely used for in situ detection of EBV-infected cells. ISH with an EBER1 probe showed that 10 of 40 NPC cases were negative for EBER1 expression. For in situ detection of EBV DNA, we used in situ PCR method which can detect one copy of EBV DNA per cell. Of the 10 EBER1-negative cases, three cases including one each of well- and poorly differentiated carcinomas and undifferentiated carcinoma were EBV DNA-positive by in situ PCR. The remaining seven were truly negative for the presence of EBV DNA. All the EBV genome-negative NPC cases examined here were histologically classified as poorly differentiated or undifferentiated carcinomas which are known to be closely associated with EBV, indicating the existence of EBV DNA-negative NPC cases, regardless of histological type or differentiation. These results indicate that there are EBV genome-positive NPC cases expressing no EBER1 and that in situ PCR can be suitable for in situ detection of EBV-infected cells, especially those expressing no EBER1 in paraffin sections. Received April 14, 1997 Accepted June 5, 1997