用双标记细胞流量检测器测定分裂期CD4~+、CD4~+CD8~+和CD8~+淋巴细胞亚类活化抗原的同时表达

外周血淋巴细胞被有丝分裂原刺激后能同时表达CD4和CD8两种抗原。进一步用克隆的外周淋巴细胞亚群实验发现,CD4~+淋巴细胞亚群能产生CD4~+辅助细胞和CD8~+抑制细胞两种细胞克隆。为了明确活化抗原     

流式细胞术检测CFSE标记人T细胞亚群增殖反应

目的探讨应用流式细胞术和活细胞荧光染料CFSE检测T淋巴细胞各亚群增殖反应的方法学。方法人外周血单个核细胞（PBMC）经CFSE染色后,分别用植物凝血素（PHA）、CD3 mAb和结核杆菌抗原（Mtb-Ag）刺激,加IL-2扩增后,用流式细胞术检测活化增殖后T细胞各亚群的比例,并用ModFit软件分析各亚群的增殖动力模型。结果PHA和CD3 mAb主要活化总T细胞,CD8^＋T细胞的增殖优于CD4^＋T细胞,但CD4^＋T细胞前4代细胞明显多于CD8^＋T细胞。Mtb-Ag主要刺激γδT细胞增殖。结论以CFSE标记淋巴细胞,结合流式细胞术可有效检测出不同T细胞亚群对不同刺激剂的增殖反应以及增殖动力学变化。     

乙醇降低人外周血T淋巴细胞活化并增加其凋亡

目的观察乙醇对人外周血T淋巴细胞亚群数量、活化功能及凋亡的影响。方法从健康供血者通过密度离心分离出外周血单个核细胞(PBMC),淋巴细胞与植物血凝素(PHA)和(30、 50)mL/L乙醇共同培养。培养12、 18、 36、 48 h后,采用流式细胞术检测各组淋巴细胞活化功能以及凋亡情况。结果 PBMC与乙醇共培养12 h后,在(30、 50)mL/L的乙醇培养条件下, T淋巴细胞的数量在12 h内无明显变化,但与空白对照相比, PHA组CD8~+ T细胞出现活化,而且50 mL/L乙醇可以抑制CD8~+ T细胞的活化。PBMC与乙醇共培养18 h,与单纯PHA组相比,乙醇和PHA联合组淋巴细胞数量减少,且随着乙醇剂量的增加淋巴细胞数量下降更明显,且PHA刺激T细胞活化减弱。PBMC与乙醇共培养36 h,与单纯PHA组相比,乙醇联合PHA处理组淋巴细胞的数量减少更显著,共培养48 h,淋巴细胞几乎消失。随着PBMC与乙醇共培养时间的延长和乙醇剂量的增加, CD3~+ T淋巴细胞凋亡比例升高。结论较高剂量乙醇处理的外周血T淋巴细胞活化减少,随着乙醇剂量的增加, T淋巴细胞及其亚群的细胞数量减少,可能与促进T淋巴细胞及其亚群凋亡有关。     

不同刺激剂对淋巴细胞中PD-1与TIM3蛋白表达的影响

目的研究不同刺激剂对人外周血淋巴细胞中PD-1与TIM3蛋白表达的影响。方法采用密度离心法分离人外周血淋巴细胞,并通过Western blot检测在抗CD3/CD28抗体、PHA、SEB、Con A4种不同刺激剂下人外周血淋巴细胞PD-1与TIM3总蛋白的变化情况,并通过流式细胞技术检测4种刺激条件下T淋巴细胞及其CD3~+CD4~+、CD3~+CD8~+亚群膜表面的PD-1与TIM3的改变。结果 Western blot结果显示,4种刺激剂均能刺激总的PD-1蛋白的表达,减少总TIM3蛋白的表达。流式细胞分析仪结果显示,在4种刺激剂作用下,人外周血T淋巴细胞表面及其CD3~+CD4~+、CD3~+CD8~+T细胞亚群膜表面的PD-1与TIM3蛋白表达均呈现升高趋势。结论 4种常见刺激剂均可诱导总PD-1蛋白和细胞膜上PD-1蛋白的表达,降低TIM3总蛋白的表达以及诱导淋巴细胞表面TIM3蛋白的表达。其中PHA较其他3种刺激剂展现出较好的剂量关系。     

SEB活化的人外周血T细胞CD25,CD69的表达

本文用超抗原葡萄球菌肠毒素B(SEB)诱导外周血淋巴细胞增殖。结果显示出微量超抗原能诱导外周血淋巴细胞的增殖,大量的增殖反应发生在SEB刺激后的第5天,增殖的细胞是CD4~+T细胞,它们由刺激前的27％增加到42％。外周血活化的T细胞不依赖外源性IL-2:大量内源性IL-2的存在抑制T细胞的增殖反应。伴随CD4~+T细胞的增殖,CD25和CD69分子表达明显增加。提示SEB能改变外周血T细胞表面的分子表达。     

慢性肾炎患者外周血T细胞亚群和共刺激分子的表达及其意义

为研究慢性肾炎患者外周血T细胞亚群和共刺激分子的表达特点及其在慢性肾炎免疫病理机制中的作用 ,本文采用免疫荧光标记和流式细胞仪分析 ,对 35例慢性肾炎患者外周血T淋巴细胞亚群和共刺激分子CD2 8、 4 1BB等的表达进行研究。结果表明 :(1)慢性肾炎患者T细胞亚群明显失衡 ,表现为CD4减少 ,CD8增加 ,CD4/CD8比值显著降低 ;(2 )共刺激分子CD2 8表达显著低于正常对照组 (CD2 8表达百分率分别为 45 95± 5 6 7和 6 6 42± 4 5 8,P <0 0 0 1) ,且CD4+ CD2 8+ T细胞和CD8+ CD2 8+ T细胞均显著减少。治疗后缓解期患者T细胞亚群失衡明显纠正 ,CD2 8+ T细胞 ,尤其是CD4+ CD2 8+ T细胞显著增多 ,而且CD4+ CD2 8+ T细胞数与患者的 2 4h尿蛋白定量呈负相关 (r= 0 47,P <0 0 1) ;(3)慢性肾炎患者共刺激分子 4 1BB在T细胞中的表达显著高于正常对照组 (表达百分率分别为 30 5 7± 8 12和 0 74± 0 2 8,P <0 0 0 1) ,治疗后的 4 1BB表达水平显著降低 ,而且 4 1BB异常高表达与CD8+ T细胞数呈正相关 (r=0 6 3,P <0 0 5 )。从而表明慢性肾炎外周血T细胞亚群失衡和T细胞活化所必需的共刺激分子CD2 8、 4 1BB异常表达 ,可能在慢性肾炎发生和病变进展中起着重要作用。     

环孢素A治疗再障和骨髓增生异常综合征T淋巴细胞异常激活的变化

研究再生障碍性贫血(AA)用环孢素A(CsA)治疗前后和骨髓增生异常综合征(MDS)患者外周血CD4+、CD8+T淋巴细胞培养前后早期激活标志CD69的表达及其意义。将外周血在PHA20μg/ml条件下进行全血细胞培养,于0h和4h分别用双色免疫荧光标记流式细胞仪对CD4+、CD8+T淋巴细胞CD69的表达进行分析。发现PHA刺激前初治SAA和MDS-RA+MDS-RAS患者CD4+、CD8+细胞CD69的表达率增高,CAA与RAEB+RAEB-T患者CD8+细胞CD69的表达率增高;PHA刺激后AA与MDS患者CD4+、CD8+细胞表达CD69明显增强,AA患者CD4+细胞CD69的表达率高于CD8+细胞。CsA治疗后SAA患者PHA刺激前CD4+、CD8+细胞CD69的表达率较治疗前明显减低,CAA患者CD8+细胞CD69的表达率较治疗前明显减低。治疗后AA患者PHA刺激后CD4+、CD8+细胞CD69的表达率较治疗前明显减低。CsA治疗有效的AA患者治疗前PHA刺激前后CD4+、CD8+细胞CD69的表达率明显增高,治疗后明显减低。初治AA患者PHA刺激前后CD4+细胞CD69的表达率均明显高于MDS患者。说明T细胞早期活化及其活化潜能增强,以及产生针对自身造血干/祖细胞的细胞毒效应在AA和MDS发病中起重要作用,CsA能抑制AA患者T细胞的早期激活。     

尘螨诱导新生儿脐血单个核细胞ICOS与转录因子表达的研究

为了解尘螨(HDM)抗原对新生儿脐血单个核细胞(CBMC)及成人外周血单个核细胞(PBMC)CD3+ICOS+细胞阳性率、转录因子T-bet、GATA-3、Foxp3 mRNA表达水平以及培养上清中IL-4、IL-10、IFN-γ表达水平的影响。用流式细胞术,检测新生儿CBMC、成人PBMC体外经PHA和/或HDM抗原刺激前、后CD3+ICOS+细胞阳性率;用RT-PCR法检测细胞体外经PHA和/或HDM抗原刺激前、后T-bet、GATA-3以及Foxp3 mRNA表达水平;用ELISA法,检测细胞在体外经PHA和/或HDM刺激前、后培养上清液中IL-4、IL-10、IFN-γ表达水平。结果表明,高剂量HDM抗原显著下调CBMC经PHA刺激后的CD3+ICOS+阳性率(P<0.05),同时也显著上调PHA刺激前其T-bet mRNA表达(P<0.05),而显著下调该类细胞经PHA刺激后的Foxp3 mRNA的表达(P<0.05)。也显著增加其PHA刺激前的IFN-γ分泌(P<0.01),减少其PHA刺激后IL-10分泌(P<0.05)。高剂量HDM抗原对CBMC的作用强于PBMC,可下调CD3+ICOS+阳性率,显著上调PHA刺激前CBMC T-bet mRNA表达,增加PHA刺激前IFN-γ的分泌,减少PHA刺激后IL-10分泌,提示早期接触高剂量HDM抗原对机体免疫功能的影响较强,可促进新生儿Th1样反应,高剂量HDM抗原可能通过作用于下调Foxp3 mRNA的表达而下调CD4+CD25+调节性T细胞的功能。     

超抗原SEA对CD4~+T细胞TCR V_β链的取用格局

用超抗原葡萄球菌肠毒素A (SEA )在体内或体外刺激C57BL/ 6小鼠 2种不同的TCRVβ链T细胞亚群 (Vβ3+ CD4+ 、Vβ1 1 + CD4+ T细胞 ) ,观察二者对超抗原的免疫应答。结果显示 :体内初次刺激后 ,2种T细胞亚群在刺激后第 2天都发生增殖 ,随后均逐渐下降至对照水平。但第 2次用同样剂量刺激后 ,Vβ3+ CD4+ T细胞群对SEA的再次刺激表现出增殖 ,而Vβ1 1 + CD4+ T细胞群对SEA再次刺激则表现出免疫无能。体外初次、再次刺激也分别获得与体内实验相同的结果。表明超抗原SEA可选择性地取用Vβ3+ CD4+ T细胞群并对其发生增殖 ,即超抗原SEA对CD4+ T细胞TCRVβ链的取用格局各有不同。     

补肾健脾方干预PPD 诱导小鼠T 细胞耗竭的实验研究

目的:研究结核分枝杆菌抗原持续刺激致T 细胞功能耗竭的机制,探究补肾健脾方对T 细胞功能耗竭的治疗作用。方法:利用BCG 初免,结核菌素纯蛋白衍化物(PPD)持续刺激C57BL/6 小鼠,模拟结核分枝杆菌抗原在病人体内持续存在所造成的慢性感染病理过程,构建T 细胞耗竭模型。在T 细胞耗竭模型基础上,给予补肾健脾方灌胃治疗。治疗3 周后检测不同实验组细胞免疫水平,包括利用流式细胞术检测脾脏CD4+和CD8+ T 细胞数目,以及细胞表面抑制性受体PD-1 的表达水平;利用ELISA 检测脾脏淋巴细胞分泌IL-2 和IFN-酌的水平;利用CFU 菌落计数检测肺脏BCG 攻击后的抗感染免疫能力。结果:与抗原短暂刺激组相比,免疫耗竭未治疗组CD4+和CD8+ T 细胞数目显著下降(P<0.05),细胞表面PD-1 表达水平显著增高(P<0.01);脾淋巴细胞分泌IL-2 和IFN-γ明显降低(P<0.01);小鼠经BCG 攻击后,抗感染保护效果显著下降(P<0.01)。经补肾健脾方治疗后,脾脏CD4+和CD8+ T 细胞数目得到明显恢复(P<0.05),CD4+ T 细胞PD-1 的表达得到显著降低(P<0.01);脾淋巴细胞分泌IL-2 和IFN-酌的水平明显增高(P<0.05);小鼠抗感染的能力显著性增强(P<0.01)。结论:通过结核抗原PPD 持续刺激成功构建T 细胞耗竭模型;补肾健脾方能逆转抗原持续刺激导致的小鼠T 细胞功能耗竭,可为临床治疗肺结核T 细胞功能耗竭提供参考。     

T cell malignancy in Richter's syndrome presenting as hyper IgM. Induction and characterization of a novel CD3+, CD4-, CD8+ T cell subset from phytohemagglutinin-stimulated patient's CD3+, CD4+, CD8+ leukemic T cells

A patient is described, having Richter's syndrome and immunodeficiency with hyper IgM, who developed suppressor T cell lymphoma (CD3+, CD4-, CD8+) following untreated helper-suppressor T cell chronic lymphocytic leukemia (CD3+, CD4+, CD8+). The neoplastic T cells in both malignancies expressed interleukin (IL) 2 receptors but were deficient in typical CD2+ and CD5+ pan T antigens. Additionally, a large percentage of malignant lymph node T cells expressed HLA-DR+ activation antigens. In vitro immunoglobulin-production experiments demonstrated that the patient's leukemic blood T cells had an excess helper function for IgM synthesis but a suppressor function for IgG and IgA synthesis by normal B and T cells. The leukemic blood T cells demonstrated a poor response to phytohemagglutinin (PHA). A defect in IL 2 receptor expression was evident in PHA-stimulated leukemic blood T cells. Of interest was the observation that PHA stimulated the induction of a novel CD3+, CD4-, CD8+ T cell subset from patient's CD3+, CD4+, CD8+ leukemic blood T cells. These PHA-induced CD3+, CD4-, CD8+ T cell subsets produced an elevated proliferative response to PHA and concanavalin A, had a helper cell function for IgM synthesis and produced highly elevated amounts of IL 2.     

Qualitative and Quantitative Analysis of T Lymphocytes During Normal Human Pregnancy

PROBLEM : Human reproduction involves contact between cells which are allogeneic to one another, however the fetus not only survives but thrives. METHODS : Aspects of T-cell-mediated immunity during normal human pregnancy were studied. PBMNCs of pregnant and nonpregnant women were stimulated with PHA and cytomegalovirus antigens (CMV). The capacity of stimulated cells to proliferate, to produce IL-2 and IFN-γ, to express IL-2 receptor (IL2R1) and the effect of rIL2 on the proliferation rate of lymphocytes were examined. FACS was utilized for T-cell subset comparisons. RESULTS : The proliferation rate, IL-2, and IFN-γ synthesis were all significantly impaired at suboptimal concentration of PHA throughout pregnancy. Exogenous rIL-2 corrected this depression of cell-mediated immunity (CMI). At optimal concentration of PHA, proliferation rate and production of IFN-γ and IL-2 were all decreased. Exogenous rIL-2 corrected these deficits only in the third trimester. Third trimester pregnant women demonstrated a significant depression of proliferation as well as IL-2 and IFN-γ production after CMV stimulation, which was partially corrected by exogenous rIL-2. FACS analysis suggested that after stimulation by CMV and optimal concentration of PHA, T cells were activated and both CD4+ and CD8+ lymphoblasts expressed normal density of IL-2R1. With suboptimal PHA, the number of activated CD4+ and CD4+IL2R1+ cells were diminished and CD4+ and CD8+ T lymphoblasts expressed lower number of IL2R1. CONCLUSIONS : CD4 T helper (Thl) cell function is down regulated progressively during the three trimesters of pregnancy without changes in the quantity of T cell subsets.     

Liver-derived T cell clones in autoimmune chronic active hepatitis: accessory cell function of hepatocytes expressing class II major histocompatibility complex molecules

Thirty T cell clones were generated from T cell blasts, infiltrating the liver of autoimmune chronic active hepatitis (CAH) patients, stimulated with autologous hepatocytes expressing class II major histocompatibility complex (MHC) molecules and interleukin 2 (IL2). Sixteen clones were CD4+ and 14 were CD8+; all were CD25+ and WT31+, revealing that all cell lines expressed the alpha/beta chains of T cell receptor. Five CD4+ and 4 CD8+ T clones proliferated in response to hepatocytes expressing both class I and class II antigens. The hepatocyte recognition was MHC restricted because only class II MHC-matched hepatocytes were able to stimulate the CD4+ T clones, while only class I-matched hepatocytes stimulated CD8+ T clones, and because MoAbs to monomorphic determinants of class II antigens or to class I antigens appeared to block the response of the CD4+ and CD8+ T clones, respectively. These findings, together with the observation that autologous irradiated peripheral blood mononuclear cells (iPBMC) were unable to stimulate the clones, indicate that the response of these clones was directed to a liver membrane antigen in association with class II or class I MHC molecules on the surface of the hepatocytes. All the CD8+ T clones and 5 CD4+ T clones expressed high cytotoxic activity in a lectin-dependent cell-mediated cytotoxicity assay; 10 CD8+ and 3 CD4+ T clones also showed natural killer (NK)-like function. The cytolytic machinery was also present in those clones (both CD8 and CD4) recognizing the HLA-matched hepatocytes. All liver-derived T clones were able to produce high amounts of interferon (IFN)-gamma, as well as being capable of secreting IL2, following PHA stimulation.     

Generation of peptide-specific CD8+ T cells by phytohemagglutinin-stimulated antigen-mRNA-transduced CD4+ T cells

Functional analysis of antigen-specific CD8(+) T cells is important for understanding the immune response in various immunological disorders. To analyze CD8(+) T cell responses to a variety of antigens with no readily defined peptides available, we developed a system using CD4(+) phytohemagglutinin (PHA) blasts transduced with mRNA for antigen molecules. CD4(+) PHA blasts express MHC class I and II, and also CD80 and CD86 and are thus expected to serve as potent antigen presenting cells. EGFP mRNA could be transduced into and the protein expressed by more than 90% of either LCL or CD4(+) PHA blasts. Its expression stably persisted for more than 2 weeks after transduction. In experiments with HLA-A*2402 restricted CD8(+) CTL clones for either EBNA3A or a cancer-testis antigen, SAGE, mRNA-transduced lymphoid cells were appropriate target cells in ELISPOT assays or (51)Cr releasing assays. Finally, using CD4(+) PHA blasts transduced with mRNA of a cancer-testis antigen MAGE-A4, we successfully generated specific CTL clones that recognized a novel HLA-B*4002 restricted epitope, MAGE-A4(223-231). Messenger RNA-transduced CD4(+) PHA blasts are thus useful antigen presenting cells for analysis of CD8(+) T cell responses and induction of specific T cells for potential immunotherapy.     

抗CD3单抗和rIL－2共刺激法诱生扩增的人CD3AK的免疫生物学特征

抗ＣＤ３单抗和ｒＩＬ－２共刺激法诱生扩增的人ＣＤ３ＡＫ是异质性细胞群，其细胞表型以ＣＤ３＋Ｔ淋巴细胞和ＣＤ５６＋ＮＫ细胞表型为主，具有活化的淋巴母细胞形态学特征，常形成集落，并表达活化淋巴细胞的表面标记，如ＩＬ－２受体和ＭＨＣⅡ类抗原。     

Human CD3+4-8-WT31- T lymphocyte populations expressing the putative T cell receptor gamma-gene product. A limiting dilution and clonal analysis

The small peripheral blood CD3+ T cell population lacking both CD4 and CD8 surface antigens has been analyzed in the present study. Enriched CD3+4-8- populations were obtained by depletion with anti-CD4 or anti-CD8 monoclonal antibodies (mAb) and complement. The resulting populations contained greater than 99% CD2+ cells, whereas CD3+ represented approximately 50%. Virtually all of the cells were CD4-8- and did not react with the WT31 mAb, specific for a framework determinant of the alpha/beta T cell receptor (TCR). In order to analyze the molecular nature of CD3-associated molecules in CD3+WT31- populations, cells were stimulated with 0.5% phytohemagglutinin (PHA) for 24 h and expanded for an additional 7-14 days in interleukin 2 (IL 2). The resulting cells were greater than 95% CD3+ and expressed neither CD4/CD8 nor WT31 antigen. Cell surface iodination followed by cross-linking and immunoprecipitation with anti-CD3 mAb showed that CD3-associated molecules consisted of a major 45-kDa band and a minor band of 43 kDa. Thus, whereas CD3-associated molecules isolated from polyclonal CD3+WT31+ populations (expanded in IL 2 under the same culture conditions) appeared as diffuse bands, CD3-associated molecules isolated from CD3+WT31- populations displayed a homogeneous molecular mass. Northern blot analysis revealed the presence of mRNA for the TCR gamma chain whereas the mRNA for the alpha chain was mostly represented by a truncated (1.2 kb) form. Also small amounts of a nonproductive mRNA for the beta chain were detected. Freshly isolated CD3+WT31--enriched populations proliferated in response to PHA and concanavalin A, moreover, IL 2 was detected in the culture supernatants after cell stimulation. By applying culture conditions which allow virtually all T cells to undergo clonal expansion, approximately 1/3 CD3+WT31- were clonogenic. In addition, the large majority of proliferating microcultures lysed the K562 cell line and about half the natural killer (NK)-resistant fresh melanoma target cells. A large number of clones derived from CD3+WT31- enriched populations by limiting dilution has been further analyzed. More than 95% of the clones were CD3+4-8-WT31-; 12/15 clones analyzed in more detail displayed NK activity and 6/15 lysed melanoma cells; in addition, all lysed P815 target cells in the presence of PHA, thus indicating that all the clonogenic CD3+WT31- cells have a cytolytic potential.     

抗CD3单抗和rIL－2共刺激法诱生扩增的人CD3AK的免疫生物学特征

抗ＣＤ３单抗和ｒＩＬ－２共刺激法诱生扩增的人ＣＤ３ＡＫ是异质性细胞群，其细胞表型以ＣＤ３＋Ｔ淋巴细胞和ＣＤ５６＋ＮＫ细胞表型为主，具有活化的淋巴母细胞形态学特征，常形成集落，并表达活化淋巴细胞的表面标记，如ＩＬ－２受体和ＭＨＣⅡ类抗原。     

Determination of co-expression of activation antigens on proliferating CD4+, CD4+ CD8+ and CD8+ lymphocyte subsets by dual parameter flow cytometry

The incidence of activation markers on proliferating CD4+, CD4+ CD8+ and CD8+ lymphocyte subsets was determined in a single laser Epics-C fluorescence-activated cell sorter system, using a series of double staining combinations. Experiments were performed after 3 days of culture with PHA on cell fractions enriched for CD4+ or CD8+ lymphocytes before initiation of culture. The percentage of CD4+, CD4+ CD8+ and CD8+ lymphocytes in the total population was determined using double staining with Leu3 PE for the detection of CD4+ cells, and Leu2 FITC for the detection of CD8+ cells. Next, double stainings with Leu3 and Leu2 antibodies conjugated with PE and antibodies directed against activation markers (M) IL-2 receptor, transferrin receptor, HLA-DR antigen and CALLA conjugated with FITC were performed, using the following combinations: Leu3 and Leu2/M, Leu3/M and Leu2/M. The expression of activation markers on CD4+ CD8+ lymphocytes was calculated from the results. Our findings indicate that CALLA is expressed on most CD4+ and all CD4+ CD8+ cells, and on a small percentage of CD8+ lymphocytes; the IL-2 receptor was expressed on most CD4+ cells, on approximately three-quarters of CD4+ CD8+ cells and half the CD8+ cells; HLA-DR was expressed on a small percentage of CD4+ cells, all CD4+ CD8+ cells and half of CD8+ cells. The transferrin receptor was almost exclusively expressed on CD4+ CD8+ cells. The standard deviation of the calculated values did not exceed 13% and this analysis can generally be applied to determine the co-expression of a third marker in a mixture of single and double stained cells using conventional methods.     

Characterization of the common acute lymphoblastic leukaemia antigen (CD10) as an activation molecule on mature human B cells.

Distinct expression pattern of CD10 molecules during B cell activation was analysed using in vivo and in vitro systems. By two-colour flowcytometrical analysis, CD10 was found to be expressed at a specific stage of in vivo activating B cells. The expression of CD10 during B cell activation appeared to be unique from that of other activation-related B cell antigens including L29, MA6, OKT9 and OKT10. Although the expression of CD10 was associated with that of the activation-related B cell antigens, CD10+ B cells could be separated in the distinct fractions to those expressing other activation-related B cell antigens when fractionated by cell gravity. In particular, certain CD10+ B cells were detected positive for the resting B cell antigen, L30. In vitro studies revealed that CD10+ B cells arose from CD10- B cells at an early step of B cell activation, and disappeared lately when activated by Staphylococcus aureus Cowan I. Collectively, CD10 was an antigen transiently expressed at an early phase of B cell activation process. Expression of CD10 and other antigens on Burkitt's lymphomas (15 cases) was studied next. All cases were CD10+, and 87% (13 cases) were also L30+. In addition, six of CD10+ L30+ cases were L29+. This observation suggested that Burkitt's lymphomas were phenotypically similar to the B cells at an early phase of activation, those expressing CD10 and L30, simultaneously. The present study has dissected a precise expression pattern of CD10 on mature B cell activation in vitro and in vivo, and could be implicated for the histogenesis of one of the poorly characterized B cell lymphoma, namely Burkitt's lymphoma.