胡桃楸提取液对肿瘤细胞增殖的抑制作用

目的考察胡桃楸提取液对肿瘤细胞Hela、K562的抑制作用和相关机制。方法用MTT方法分析胡桃楸提取液对Hela、K562细胞增殖的影响。采用端粒酶PCR ELISA试剂盒分析胡桃楸提取液对Hela、K562细胞端粒酶的影响。结果 Hela细胞24、48和72 h的LD50分别为406.18μg/mL、319.48μg/mL和112.84μg/mL。K562细胞24 h LD50为154.50μg/mL。HLF细胞LD50为918.69μg/mL。胡桃楸提取液可抑制Hela细胞和K562细胞的端粒酶活性,而对HLF细胞端粒酶活性影响不大。结论胡桃楸提取液对Hela细胞、K562细胞有抑制作用,在低浓度下对HLF细胞杀伤不大。对肿瘤细胞抑制作用可能与抑制端粒酶活性相关。     

顺铂诱导人宫颈癌细胞系P27表达及其超微弱发光测定的意义

目的:探讨化疗药物对肿瘤增殖活性的影响.方法:选择人宫颈癌细胞系Hela分为两组,分别采用MTT比色法分析测定顺铂处理Hela细胞的浓度;免疫组化SP法分别检测Hela细胞中P27蛋白表达;流式细胞仪分析加药前后细胞周期变化及凋亡情况;用IFFM-D型流动式化学发光仪检测细胞的超弱发光强度.结果:顺铂处理Hela细胞48h的IC50值为3mg/L,当DDP浓度,在3mg/L以下时,对Hela细胞无明显毒性作用,超过此浓度时,其毒性呈剂量效应关系(P<0.001);流式细胞仪分析细胞周期可见与Hela细胞相比较,Hela+DDP细胞的G2期细胞数增多,而G1,S期的细胞数明显减少(P<0.01);从细胞调亡检测显示Hela与Hela+DDP相比,细胞凋亡率在不同时间点明显升高,在24h,48h,72h结果分别为(11.4±5.8、21.8±7.9、32.5±11.6)%.免疫组化结果显示Hela+DDP与Hela细胞相比细胞膜上P27蛋白高表达;在10-4mol/L鲁米诺及0.3%的双氧水(H2O2)条件下Hela细胞超弱发光强度高于用Hela+DDP细胞9P<0.001).结论:超弱发光能够快速、准确、有效地反映肿瘤细胞氧化代谢特点和增殖活动,也可用于筛选敏感的化疗药物.     

HPV-siRNA 对Hela细胞生长抑制作用的实验研究

以HPV18 E6基因为靶位,研究siRNA对宫颈癌Hela细胞生长的抑制作用。设计并合成siRNA,脂质体siNEO FX转染Hela细胞,分别用MTT法,双层软琼脂克隆形成试验和流式细胞术分析了siRNA对Hela细胞体外生长增殖活力、细胞周期分布的作用。siRNA作用后的Hela细胞增殖速度减慢,软琼脂克隆形成率降低,G0/G1期细胞比率增加。HPV18 E6 siRNA能抑制Hela细胞体外生长增殖能力并诱导细胞周期重新分布。     

柚皮中的有效成分对人子宫颈癌Hela细胞增殖及凋亡的影响

目的探讨柚皮素或柚皮苷对人子宫颈癌Hela细胞增殖及凋亡的影响。方法柚皮素或柚皮苷(0.250、0.125、0.063g/L)作用于人子宫颈癌Hela细胞后,MTT比色法检测Hela细胞增殖活性和半数抑制浓度(half maximal inhibitory concentration,IC50);流式细胞术检测柚皮素对Hela细胞凋亡的影响。结果柚皮素能抑制Hela细胞增殖,且呈剂量和时间依赖性,24、48和72hIC50值分别为0.24、0.11和0.07g/L;柚皮苷无抑制Hela细胞增殖的作用。柚皮素组(0.22g/L、0.11g/L、0.05g/L,作用48h)人子宫颈癌Hela细胞凋亡率高于对照组,差异有统计学意义(P=0.000239681,P=0.00012746,P=5.09328E-05,P0.01)。结论柚皮中黄酮类提取物具有抑制人子宫颈癌Hela细胞增殖作用,其中柚皮素作用明显,部分作用机制与诱导肿瘤细胞凋亡有关。柚皮苷无抗人子宫颈癌作用。     

重组七鳃鳗细胞毒素蛋白rLj-RGD3表达及对Hela细胞活性的影响

为研究重组七鳃鳗细胞毒素蛋白rLj-RGD3的抗肿瘤活性,确定其生物学地位及意义,本研究提取成体七鳃鳗(Lampetra japonica)口腔腺组织总RNA,经RT-PCR获得cDNA序列长度为357bp的目的基因片段,将其克隆于pET23b载体,获得带有组氨酸标签的分子量为15kD的基因重组蛋白rLj-RGD3的高效可溶性表达,通过组氨酸亲和层析纯化蛋白。采用MTT法检测不同浓度rLj-RGD3对bFGF诱导下的Hela细胞增殖的抑制作用,结果表明rLj-RGD3能显著抑制Hela细胞的增殖,IC50为2.6μmol/L。rLj-RGD3作用后的Hela细胞经Hoechst染色及DNAladder检测结果显示,细胞均发生凋亡。rLj-RGD3对Hela细胞黏附玻连蛋白(VN)作用的实验结果为有效抑制。采用Transwell细胞培养板对bFGF诱导下的Hela细胞迁移实验表明,rLj-RGD3能够抑制Hela细胞的迁移,且抑制率达60%。采用人工基质膜基质Matrigel及Transwell模仿体内环境研究rLj-RGD3对Hela细胞浸润行为实验显示,以bFGF为趋化剂的Hela细胞穿透Matrigel的...     

不同方法提取的板栗花黄酮对Hela细胞生长的影响

采用MTT法,以正常生长的人肾上皮细胞293T为对照,探索半仿生法、乙醇回流法和水提法得到的板栗花黄酮对人宫颈癌Hela细胞生长的影响。结果表明:半仿生法、乙醇回流法和水提法制得的板栗花黄酮在实验浓度范围内能有效抑制Hela细胞的生长,其对Hela细胞的半数抑制率(IC_(50))分别为7.30、9.94、22.48μg/m L,抑制作用效果呈剂量依赖性特点,而对293T细胞的IC_(50)分别为54.71、54.17、153.44μg/m L,在低于30μg/m L浓度范围内,对Hela细胞生长抑制作用显著(P0.05),而对293T细胞生长抑制不明显(P0.05)。实验结果表明板栗花黄酮具有很好的抑制Hela细胞生长的活性,且半仿生-板栗花黄酮抑制作用是三种提取方法中效果最好的。     

乳酸杆菌发酵滤液对人宫颈癌细胞株Hela细胞的细胞周期和细胞凋亡的影响

目的观察乳酸杆菌DM9811发酵滤液对宫颈癌细胞株Hela细胞的细胞周期和细胞凋亡的影响,探索乳酸杆菌发酵滤液对宫颈癌细胞作用的可能机制。方法用光镜、电镜和流式细胞仪分析不同浓度乳酸杆菌DM9811发酵滤液对Hela细胞凋亡的诱导效果;用流式细胞仪分析不同浓度乳酸杆菌DM9811发酵滤液对Hela细胞细胞周期的影响。结果（1）乳酸杆菌DM9811发酵滤液可诱导宫颈癌Hela细胞凋亡。形态学观察处理后的Hela细胞,可见细胞变形,细胞皱缩,体积变小,细胞间隙增大,细胞核固缩。流式细胞仪分析,1%、2%的乳酸杆菌DM9811发酵滤液在48、72h可诱导Hela细胞凋亡;5%的乳酸杆菌发酵滤液在24、48和72h均可诱导Hela细胞凋亡。（2）乳酸杆菌DM9811发酵滤液阻滞宫颈癌Hela细胞于S期,不同浓度的乳酸杆菌发酵滤液作用24、48和72h均可使S期细胞比阴性对照组增多。结论乳酸杆菌DM9811发酵滤液可诱导部分Hela细胞凋亡,其对Hela细胞的生长抑制作用可能通过S期阻滞实现。     

HeLa/GFP-Plk1/Cherry-H2B稳定细胞系的构建简

目的：构建可研究Polo样激酶1（Plkl）定位的HeLa细胞系。方法：用PCR方法扩增Plkl基因,定向克隆到pRex-EGFP-IRES-Hygm载体中,构建pRex-EGFP-Plkl-IRES-Hygro表达载体;利用逆转录病毒感染的方法,向HeLa细胞系中依次转染pRex-EGFP-Plkl-IRES-Hygro、pRex-Cherry-H2B-IRES-Hygro,构建Hela/GFP-Plkl/Chef．ry-H2B稳定细胞系;激光共聚焦显微镜观察Hela/GFP-Plkl/Cherry-H2B稳定细胞系在不同有丝细胞分裂期时Plkl的定位。结果：质粒酶切及测序证明pRex-EGFP-Plkl-IRES-Hygro载体构建正确;在Hela/GFP-Plkl/Cherry-H2B稳定细胞系有丝分裂中期和末期时,观察到Plkl分别定位于着丝粒和中间体上。结论：构建了Hela/GFP-Plkl/Cherry-H2B稳定细胞系,为研究Plkl在有丝分裂不同时期的调控机制提供了细胞模型。     

白屈菜红碱对宫颈癌细胞的抑制作用研究

目的:研究白屈菜红碱(chelerythrine,CHE)对宫颈癌细胞(Hela)的增殖抑制作用,为CHE在预防和治疗宫颈癌方面提供实验依据.方法:不同浓度CHE作用于体外培养的Hela细胞后,采用台盼蓝拒染法和噻唑蓝(MTT)法研究白屈莱红碱时宫颈癌(Hela)细胞增殖能力的影响,流式细胞仪(FCM)检测细胞周期变化.结果:细胞接种密度越小、药物作用时间越长、药物浓度越大,CHE对Hela细胞的增殖抑制率越大,过大的细胞接种密度以及过低的药物浓度均不会引起明显的细胞死亡;CHE作用后的Hela细胞周期分布有明显变化,G1期细胞减少,S期和G2/M期细胞明显增多.结论:CHE在体外能明显抑制Hela细胞生长,其机理可能与CHE阻滞细胞周期、诱导细胞凋亡有关.     

甲硫氨酸脑啡肽和抗δ阿片受体抗体对小鼠骨髓瘤细胞信号传递系统的作用

为了探讨阿片肽与细胞表面受体结合后所产生的生物效应及其机制 ,用不同浓度甲硫氨酸脑啡肽 ( MENK)及抗 δ阿片受体单克隆抗体处理小鼠的骨髓瘤细胞 ( NS- 1 ) ,然后测定蛋白激酶A( PKA) ,蛋白激酶 C( PKC)活性及三磷酸肌醇 ( IP3 )含量 .研究结果表明 ,NENK可升高细胞胞浆及胞膜 PKA的活性 ,且这一作用可被抗δ阿片受体抗体所拮抗 .MENK对 PKC影响呈双向反应 ,0 .1 μmol/L MENK可以升高胞浆 PKC活性 ,但却明显降低胞膜 PKC活性 ;在 MENK浓度为 1 0μmol/L时则情况刚好相反 .1 μmol/L的 MENK可明显降低胞浆及胞膜 PKC活性 ,抗体可拮抗这种下调作用 .MENK可降低细胞内 IP3 的含量 ,且这一作用可被抗δ阿片受体抗体所拮抗 .由此可以推论 :MENK在与 δ阿片受体结合后 ,可以经过多种信号传导系统来调节细胞功能 ,从而产生不同的生物效应 .     

Monoclonal antibody (H107) inhibiting IgE binding to Fc epsilon R(+) human lymphocytes

A hybridoma-producing monoclonal antibody blocking the binding of human IgE to lymphocytes Fc receptor (Fc epsilon R) was established by the fusion of murine myeloma cells. P3X63.653.Ag8, with BALB/c spleen cells immunized with Fc epsilon R(+) human B lymphoblastoid cell line cells, RPMI1788. A clone of the hybridoma (H107) produced a monoclonal IgG2b antibody that inhibited the rosette formation of Fc epsilon R(+) human B lymphoblastoid cell line cells (RPMI1788, RPMI8866, CESS, Dakiki, and IM9) with fixed ox red blood cells (ORBC) conjugated with human IgE (IgE-ORBC). In contrast, the rosette formation with IgG-conjugated ORBC (IgG-ORBC) on Fc gamma R(+), Fc epsilon R(-) Daudi cells were not affected by the H107 antibodies. A close association of Fc epsilon R and the antigenic determinant recognized by H107 antibody was suggested by the following results. First, the bindings of 125I-labeled IgE (125I-IgE) or 125I-labeled H107 IgG2b antibody (125I-H107) to RPMI8866 cells were inhibited by cold human IgE and H107 IgG2b but not by other classes of human Ig (IgA and IgG), MPC11 IgG2b, or unrelated monoclonal antibodies. Second, H107 antibody reacted with Fc epsilon R(+) B cell lines but not with Fc epsilon R(-) B cell lines as determined by an indirect immunofluorescence. Third, Fc epsilon R(+) cells were depleted by the incubation in the dish coated with H107 antibody or IgE but not in the dish coated with unrelated antibodies. Finally, there was a correlation between the increase of Fc epsilon R(+) cells and that of H107(+) cells in the peripheral blood lymphocytes of the patients with atopic dermatitis. The surface antigens on Fc epsilon R(+) RPMI8866 cells recognized by H107 antibodies had the molecular size of 45,000 as determined by immunoprecipitation and sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis.     

巨细胞病毒单克隆抗体的建立和应用

应用人巨细胞病毒(CMV)AD169株免疫BALB/C小鼠,取脾细胞与SP 2/0小鼠骨髓瘤细胞融合,得到4株(12H、3H、47C和6H)能分泌单克隆抗体(McAb)的杂交瘤细胞。其中47C株McAb(滴度≥512 000)经辣根过氧化物酶标记,能与细胞培养中的AD169株和Davis株CMV发生特异性核内染色反应。14份出现CMV典型病变的临床阳性标本中,12份呈明显的阳性反应,另2份为弱阳性反应,而对正常细胞及感染其它病毒的细胞均无染色反应,说明该McAb具有较好的特异性。用于鉴定分离的毒株,一天内可出结果,比中和试验快速、简便。     

Autoimmunization in murine graft-vs-host disease. I. Selective production of antibodies to histones and DNA

A lupus-like disease characterized by a severe immune complex glomerulonephritis and IgG autoantibody production was induced in (C57BL/6 X DBA/2)F1 mice by injection of parental DBA/2 lymphoid cells. The ensuing graft-vs-host (GVH) reaction resulted in a 10- and a 100-fold increase in serum IgG antibody levels to denatured DNA and total histones, respectively, compared with that in F1----F1 control mice. The level of anti-DNA antibodies peaked 2 wk after injection of DBA/2 cells and preceded peak anti-histone levels by approximately 2 wk. Anti-histone antibodies were generated predominantly to histones H1, H2A, and H2B, a profile different from that observed in NZB/NZW and MRL-lpr/lpr mice. The marked increase in IgG antinuclear antibodies did not correlate with increases in total IgG serum levels and was not associated with comparable increases in antibodies to transferrin, hemoglobin, fibrinogen, or thyroglobulin. Selective autoantibody production was also observed in vitro, wherein GVH spleen cells produced high levels of IgG antibodies to total histones and denatured DNA but not to these non-nuclear protein antigens. In contrast, spleen cells stimulated in vitro with lipopolysaccharide produced equivalent amounts of antibodies to all antigens tested. Our results are in agreement with those of other investigators and collectively suggest that IgG autoantibodies in GVH disease, and possibly in spontaneous lupus-like disease, are not secondary to a generalized B cell activation, but may be selectively generated in response to self antigens with unique configurational properties.     

Cellular basis of in vitro anti-DNA antibody production: evidence for T cell dependence of IgG-class anti-DNA antibody synthesis in the (NZB X NZW)F1 hybrid

An in vitro system was designed to measure anti-DNA antibody synthesis, and the cellular basis of this autoantibody production in NZB X NZW (B/W)F1 (B/W F1) mice was analyzed. The spleen cells from old B/W F1 mice contained a number of B cells that spontaneously produced anti-DNA antibodies of both IgM and IgG classes in the absence of stimulants, thereby demonstrating that these B cells had been activated in vivo. These activated B cells could be removed by Sephadex G-10 column (G-10) filtration. Such G-10-passed, homogeneously small B cells were activated by the stimulant lipopolysaccharide (LPS) and produced both IgM and IgG class anti-DNA antibodies. The G-10-passed cells contained both B and T cells, and the cytotoxic treatment of the cells with monoclonal antibodies to T cells, anti-Thy-1 and anti-L3T4, abolished the LPS-induced IgG class, but not IgM class, anti-DNA antibody syntheses. Thus, the LPS-induced production of IgG class anti-DNA antibodies in B/W F1 mice is regulated by T cells. Reconstitution experiments revealed the requirement of T-B cell contact but not of the proliferative response of T cells. Moreover, there was no apparent adherent cell requirement. Such IgG class anti-DNA antibodies were produced only by spleen cells from old B/W F1 mice, but not from young B/W F1, NZB, NZW, and C57BL/6 mice. Like IgM class anti-DNA antibodies, LPS-induced synthesis of polyclonal IgM was T cell-independent. Only a slight reduction in the polyclonal IgG synthesis was observed after the G-10-passed cells had been treated with anti-Thy-1 antibody plus complement. This study should facilitate investigation of cell to cell interactions in the formation of autoantibodies and their correlations to immunologic abnormalities in autoimmune disease.     

IgG subclass expression by human B lymphocytes and plasma cells: B lymphocytes precommitted to IgG subclass can be preferentially induced by polyclonal mitogens with T cell help

The human IgG subclasses expressed by circulating B lymphocytes, tissue plasma cells, and plasma cells generated from B cell precursors in response to the polyclonal mitogens LPS and PWM were examined by immunofluorescence using subclass-specific monoclonal antibodies. The subclass distribution observed for circulating B lymphocytes was IgG2 (48%) greater than IgG1 (40%) greater than IgG3 (8%) greater than IgG4 (1%), while the distribution among IgG plasma cells in bone marrow, blood, spleen, and tonsils was IgG1 (64%) greater than IgG2 (26%) greater than IgG3 (8%) greater than IgG4 (1%). Multiple IgG isotypes were not observed on B cells or in plasma cells. Although IgG plasma cell responses to both LPS and PWM were T cell dependent, the distributions of IgG subclasses elicited were strikingly different. In control and LPS-stimulated cultures of blood mononuclear cells, the induced plasma cells expressed the IgG subclass distribution: IgG2 greater than 80%, IgG1 less than 20%, IgG3 less than 1%, IgG4 less than 1%. In PWM-stimulated cultures, the subclass distribution, IgG1 approximately 65%, IgG2 approximately 25%, IgG3 approximately 7%, IgG4 approximately 1%, was in perfect concordance with the in vivo subclass distribution of IgG plasma cells. Selective inhibition of suppressor T cell activity by x-irradiation and mitomycin C treatment did not alter the IgG subclass distribution pattern induced by LPS and PWM. Monoclonal antibodies were used to deplete selectively the B cell precursors bearing IgG1, IgG2, or IgG3 before PWM stimulation of blood mononuclear cells. In each instance, a reduction was observed only in the subpopulation of plasma cells producing the homologous IgG subclass. The results indicate that T cells can preferentially influence the terminal differentiation of B cells that are precommitted to different IgG subclasses.     

抗禽流感病毒H5N1亚型单克隆抗体制备初报

目的制备禽流感H5N1亚型病毒的单克隆抗体,为相关研究提供工具。方法以禽流感H5N1亚型病毒免疫BALBc小鼠,取其脾细胞和SP20细胞融合,用血凝抑制试验(HI)和酶联免疫反应(ELISA)检测培养上清,并将阳性融合细胞稀释克隆化3次直至100%孔均为阳性,筛选阳性克隆株,运用免疫荧光法评估单克隆抗体检测病毒感染的犬肾细胞(MDCK)。结果得到三株稳定分泌抗体的细胞并命名为F8、F9、G11,抗体亚型鉴定结果分别为IgG1、IgG2a和IgG2b;在免疫荧光法单克隆抗体能够检测出感染MDCK细胞的病毒。结论建立了3株抗禽流感H5N1亚型病毒的单克隆抗体细胞株,其产生的一株高特异性的McAbG11能够用于H5N1亚型禽流感病毒感染诊断,并可能应用于禽流感病毒H5N1亚型感染的防治。     

Inhibition of anti-IgM and growth factor-induced proliferation of guinea pig B cells by one of two distinct Fc gamma receptors on the cells

Guinea pig B cells were found to proliferate when co-stimulated with F(ab')2 of rabbit anti-guinea pig IgM and human 12-kDa B cell growth factor (BCGF), though the proliferation did not occur with the replacement of the F(ab')2 by its parent IgG antibody. In addition, the intact antibody inhibited the proliferation induced by F(ab')2 of anti-IgM and BCGF. Because both two distinct types of FcR for IgG on the B cells, one specific for IgG2 (Fc gamma 2R) and the other for both IgG2 and IgG1 (Fc gamma 1/gamma 2R), can bind rabbit IgG, we determined whether they participate in the inhibition of the B cell proliferation by intact anti-guinea pig IgM antibody. Blocking Fc gamma 1/gamma 2R by F(ab')2 of anti-Fc gamma 1/gamma 2R mAb significantly reversed the inhibitory effect of intact anti-IgM antibody. F(ab')2 of anti-Fc gamma 2R mAb, however, was not effective. Furthermore, guinea pig IgG1 and IgG2 anti-rabbit IgG antibodies suppressed similarly the B cell proliferation induced by F(ab')2 of rabbit anti-IgM and BCGF. These results show that between these two types of Fc gamma R on B cells, Fc gamma 1/gamma 2R alone is involved in the regulation of anti-IgM and BCGF-induced B cell proliferation, and inhibits the response when cross-linked to the surface IgM.     

Characteristics of in vitro production of antibodies to DNA in normal and autoimmune mice.

The in vitro production of antibodies to dsDNA was studied with spleen cells from normal and autoimmune mice. After culture for 4 days, the binding of dsDNA in the culture supernatant was measured by a radioimmunoprecipitation assay. The production of antibodies to dsDNA by spleen cells appeared at 15 hr after culture and reached a plateau at 24 hr. No antibodies were produced by thymus cells or splenic T cells. The specificity for dsDNA was shown by competitive inhibition with nonradioactive nucleic acids. Autoimmune strains of mice (NZB/NZW, BXSB, MRL/1) produced more antibodies to dsDNA than did several control strains. Young B/W mice and control strain mice produced mainly IgM antibodies, whereas older B/W mice produced predominantly IgG antibodies to dsDNA. The in vitro production of antibodies to dsDNA by aged B/W spleen cells was macrophage and T cell dependent.     

Autoimmunity after induction of neonatal tolerance to alloantigens: role of B cell chimerism and F1 donor B cell activation

BALB/c mice rendered tolerant by the neonatal injection of semiallogeneic (C57BL/6 X BALB/c)F1 spleen cells develop features of autoimmune disease. The possible mechanisms involved in autoantibody production, particularly anti-DNA antibodies, were investigated. In the first 5 wk, there was polyclonal B cell activation, as indicated by marked hypergammaglobulinemia, with a predominance of IgG1 and an increased production of antihapten antibodies. IgG1 anti-SSDNA and anti-DSDNA antibodies were detected with similar kinetics, but at higher titers than the anti-hapten antibodies. Also, there was a correlation between the effective induction of tolerance, as evaluated by the measurement of alloantigen-specific cytolytic T lymphocyte precursors, the persistence of B cell chimerism, and the production of anti-DNA antibodies. Anti-DNA antibodies were observed only in mice exhibiting a persistence of immunoglobulins bearing the donor's allotype. To determine the origin of anti-DNA antibodies, experiments were conducted whereby newborn BALB/c (Igh-1a) mice were injected with F1 cells from mice resulting from a crossing between Igh congenic BALB/c mice bearing the IgCHb allotype and conventional C57BL/6 mice (Igh-1b). All anti-DNA and anti-hapten antibodies exhibited the Igb allotype and thus were produced by the F1 donor B cells. The initial phase of tolerance induction was apparently associated with an allogeneic helper effect, because DNP-KLH-primed F1 donor cells transferred to newborn BALB/c could be stimulated after challenge with DNP-BGG. The triggering of persisting auto-reactive F1 donor B cells may reflect an activation by "incompletely" tolerant semiallogeneic T cells.     

Production and characterization of monoclonal antibodies to rat liver arginase

Rat liver arginase was purified and five monoclonal antibodies were produced by fusion of spleen cells from a Balb/c mouse and the myeloma cell line P3-X36-Ag-U1. One, R2D19, of five antibodies belonged to the IgG2a subclass, the other four, R1D81, R1G11, R2E10, and R2G51, were of the IgG1 type. The R1D81 cross-reacted with human liver arginase. This antibody inhibited the arginase activity, competing with arginine. These results suggest that R1D81 binds to the catalytic site of arginase. The R2D19 also inhibited the enzyme activity but acted as a noncompetitive inhibitor. With the use of R1D81 and a polyclonal anti-human liver arginase antibody conjugated with alkaline phosphatase, a sandwich enzyme-linked immunosorbent assay (ELISA) was developed for the quantification of human arginase. Specificity of monoclonal antibodies for rat liver arginase was examined by means of the sandwich ELISA. Eight pairs of monoclonal antibodies could form a sandwich with the arginase. Only the R2E10 could be used for both the first and the second antibody in the sandwich system. In other cases, monoclonal antibodies could not be interchanged between solid and liquid phase.