Basic regulatory science behind drug substance and drug product specifications of monoclonal antibodies and other protein therapeutics

In this review,we focus on providing basics and examples for each component of the protein therapeutic specifications to interested pharmacists and biopharmaceutical scientists with a goal to strengthen understanding in regulatory science and compliance.Pharmaceutical specifications comprise a list of important quality attributes for testing,references to use for test procedures,and appropriate acceptance criteria for the tests,and they are set up to ensure that when a drug product is administered to a patient,its intended therapeutic benefits and safety can be rendered appropriately.Conformance of drug substance or drug product to the specifications is achieved by testing an article according to the listed tests and analytical methods and obtaining test results that meet the acceptance criteria.Quality attributes are chosen to be tested based on their quality risk,and consideration should be given to the merit of the analytical methods which are associated with the acceptance criteria of the specifications.Acceptance criteria are set forth primarily based on efficacy and safety profiles,with an increasing attention noted for patient-centric specifications.Discussed in this work are related guidelines that support the biopharmaceutical specification setting,how to set the acceptance criteria,and examples of the quality attributes and the analytical methods from 60 articles and 23 pharmacopeial monographs.Outlooks are also explored on process analytical technologies and other orthogonal tools which are on-trend in biopharmaceutical characterization and quality control.

Hepatitis B virus reactivation in patients treated with monoclonal antibodies

Hepatitis B virus(HBV)reactivation poses a significant clinical challenge,espe-cially in patients undergoing immunosuppressive therapies,including mono-clonal antibody treatments.This manuscript briefly explores the complex rela-tionship between monoclonal antibody therapy and HBV reactivation,drawing upon current literature and clinical case studies.It delves into the mechanisms underlying this phenomenon,highlighting the importance of risk assessment,monitoring,and prophylactic measures for patients at risk.The manuscript aims to enhance the understanding of HBV reactivation in the context of monoclonal antibody therapy,ultimately facilitating informed clinical decision-making and improved patient care.This paper will also briefly review the definition of HBV activation,assess the risks of reactivation,especially in patients treated with monoclonal antibodies,and consider management for patients with regard to screening,prophylaxis,and treatment.A better understanding of patients at risk can help clinicians provide optimum management to ensure successful patient outcomes and prevent morbidity.

Monoclonal antibodies as therapeutic agents in oncology and antibody gene therapy

Antibodies as therapeutic agents are mostly used in oncology, as illustrated by their applications in lymphoma, breast cancer or colorectal cancer. This review provides a brief historical sketch of the development of monoclonal antibodies for cancer treatment and summarizes the most significant clinical data for the best-established reagents to date. It also discusses strategies to improve the anti-tumor efficacy of antibody therapy, including antibody gene therapy and exploitation of bone marrow derived primary mesenchymal stem cells as the antibody gene transporter.

PRODUCTION AND APPLICATION OF MONOCLONAL ANTIBODY TO POLYAMINE (PREPARATION AND CHARACTERISTICS OF MONOCLONAL ANTIBODIES AGAINST SPERMIDINE)

A monoclonal antibody was first prepared by fusion of mouse myeloma cells (SP2/0-Ag-14) with spleen cells isolated from male BALB/ c mice immunized with spermidine-bovine serum albumin conjugate (SPD- BSA). The hybridoma cell line producing antibody specific for spermidine was cultured in vitro and after i. p. into mice, the ascitic fluid gave suitably high dilution titres (1: 106) by enzyme immunoassay. This monoclonal antibody is of IgG1 class and the bimolecular compleex with molecular weight of 52KD and 27 KD. The monoclonal antibody was clearly specific to spermidine comparing with spermine or putriscine. Monclonal antibody may prove to be useful in the rapid diagnosis and evaluation of patients with cancer.

Analysis of Specific Th1/Th2 Helper Cell Responses and IgG Subtype Antibodies in Anti-CD4 Monoclonal Antibody Treated Mice with Autoimmune Cardiomyopathy

The cytokine repertoire of ADP/ATP carrier-specific humoral immune responses and the cytokine-dependent anti-ADP/ATP carrier antibody IgG subclasses were examined in a cohort of ADP/ATP carrier-immunized BALB/c mice treated with anti-CD4 monoclonal antibody. Eighteen male BALB/c mice （6–8 weeks old） were randomized into 3 groups： dilated cardiomyopathy （DCM） group, DCM-tolerance （Tol） group and control group. The mice in DCM group were immunized with the peptides derived from human ADP/ATP carrier protein for 6 months and mice in the control group were sham-immunized, while the mice in DCM-Tol group were immunized with ADP/ATP carrier protein and anti-CD4 McAb simultaneously. Serum autoantibody against ADP/ATP carrier and IgG subclasses were measured by ELISA, intracellular cytokines IFN-γ and IL-4 of Th cells were moni- tored with flow cytometry, and splenic T cell cytokines IFN-γ, IL-2, IL-4 and IL-6 were detected by using real-time fluorescent quantitative PCR. The results showed that the autoantibody against ADP/ATP carrier was found in all mice in DCM group, and the antibody level, serum IgG1 and IgG2a subclasses, cytokines in T cells and Th cells were all elevated in DCM group, as compared with those in control group （P〈0.01）. On the other hand, in DCM-Tol group, the autoantibody level and contents of all the cytokines were significantly different from those in DCM group （P〈0.01）, and were close to those in control group. And the levels of IgG1, IgG2a, IgG2b and IgG3 were influenced, to varying degrees, by anti-CD4 McAb as compared with those in DCM group. All these four types of IgG subclasses were substantially decreased in DCM-Tol group as compared with DCM group. It is concluded that the treatment with anti-CD4 McAb could prevent the activation of T cells, reverse the abnormal secretion of cytokines and the imbalance between Th1/Th2 cell subsets and abnormal production of autoantibody against ADP/ATP carrier, and eventually avoid myocardial injuries.

THE USE OF ANTI-HUMAN GLIOMA MONOCLONAL ANTIBODIES FOR TARGETING CHEMOTHERAPY OF BRAIN GLIOMAS(PREPARATION AND CYTOTOXIC PROPERTIES OF ANTIBODY-ADRIAMYCIN IMMUNOCONJUGATES)

Immunoconjugates are antibody-drug hybrid molecules which combine the exquisite selectivity or monoclonal antibodies with the potent toxicity of anticancer agents. A monoclonal antibody SZ39 against human brain gliomas was used as a drug carrier. Adriamycin (ADR) was bound covalently to SZ39 to form a SZ39-ADR conjugate. The cytotoxic activity of the SZ39-ADR conjugate was tested in vitro and demonstrated potent and specific killing of cells derived from a human malignant glioma. 50% inhibitory concentration (IC50) for SZ39-ADR to 'target' cells was 8.14×10-9 M. An index of specificity between 'target' and 'non-target' cells was calculated to be 88-fold. These data suggest that the SZ39-ADR may use as a potent and cell type-specific agent and is a likely candidate for the targeting chemotherapy of malignant gliotnas.

Development and Characterization of Monoclonal Antibody Specific to Nuclear Protein of Avian Influenza Virus Type A

Five monoclonal antibodies（Mabs） to nuclear protein of avain influenza virus（AIV） were developed by syncretizing SP 2/0 and the spleen cells from BALB of mice immuized with H9 subtype AIV. Specificity of these Mabs were identified by immunofluorescent assay（IFA） and enzyme linked immunosorbent assay （ELISA）. These five Mabs which were named as AIV-NP-2C3, AIV-NP-6A5, AIV-NP-3 H9, AIV-NP-7B4, AIV-NP-2H4 could react with all viruses of AIV-H9 strains in tests. The result of Western blotting showed that only the 60 ku protein antigen of AIV-H9 could be recognized by the Mabs but never recognized by New castle disease virus, REV and infectious bursa disease virus. The result of preliminary application showed that avian influenza viruses could be deetected bv Mabs in IFA and ELISA. All these Mabs will probably play important roles in preventing and monitoring avian influenza viruses.

Establishment of Monoclonal Antibody Competitive ELISA Using Monoclonal Antibody Against VP1 Protein of Asia 1 Type Foot-and-Mouth Disease Virus

Using the purified VP1 protein of Asia 1 type foot-and-mouth disease virus as the antigen, the purified monoclonal antibody was labeled by the sodium periodate method and the monoclonal antibody competitive ELISA was established in this study. Ten positive porcine foot-and-mouth disease serums and more than two hundreds negative serum were tested, and the results were the same as the background of samples. The sensitivity test and replicate test indicated that this method was stable and sensitive, which was suitable for monitoring Asia 1 type porcine foot-and-mouth disease virus antibody.

A MONOCLONAL ANTIBODY RECOGNIZING NON DERIVATIVE 13 HYDROXY GIBBERELLINS AND THEIR GLUCOSIDES *

The production and characterization of a monoclonal antibody (MAb AB10) against GA 3 glucoside as well as GA 3 is described. MAb AB10 was derived from an immunogen in which human serum albumin (HSA) was linked to GA 3 at carbon 3. This antibody showed high affinity for GA 3 glucoside as well as for 13 hydroxy gibberellins (GA 1, GA 3, GA 5, etc). The affinity of MAb AB10 for 13 hydroxy GAs was significantly reduced by methylation of the 7 oic acid but not by glycosylation of 3 hydroxyl group. Based on this antibody, both of competitive enzyme linked immunosorbent assays (ELISAs) for GA 3 glucoside and for GA 3 were developed. These two ELISAs displayed linear detection ranges from 0 2 pmol to 20 pmol. Using these assays, the fluctuation of GA 3 like and GA 3 glucoside like substances in the leaves of Rumex japonicus was investigated. The results indicated that the glycosylation of free GAs was connected with leaf senescence and that the function of 6 benzyl amino purine in retarding the leaf senescence was probably related to delaying the process of glycosylation of free GAs.

Preparation and Preliminary Identification of Fluorescein Labeled Monoclonal Antibody against Canine Distemper Virus

[Objective] The aim of the present study was to develop a direct immunofluorescence method for the diagnosis of canine distemper （CD） with FITC-conjugated monoclonal antibodies （FITC-McAb）.[ Metbod] The McAb against CDV, designated as CE3, was purified with protein G and labeled with FITC through agitation method. After purification and identification, the optimal working concentration of FITC-labeled CE3 was determined. Then 61 clinical samples of suspected canine distemper were detected by direct immunofluorescence assay. [ Result] The absorption test, blocking test and specificity test showed that the labeled antibody had high specificity and sensitivity, but didn＇t have cross reaction with canine parvovirus （CPV）, canine parainfluenza virus （CPIV）, canine adenovirus （CAV） and rabies virus （RV）. The optimal working concentration was 1：80. The positive rate of clinical suspected samples was 48%. [ Conclusion] The direct immunofluorescence assay developed in this study was rapid, specific and convenient, and had great significance for the early diagnosis of canine distemper.

Preparation and Identification of Specific Monoclonal Antibody against Porcine Circovirus Type 2

BALB/c mice were immunized using synthetic tandem polypeptide of Cap protein epitope of porcine circovirus type 2 （PCV2） as the antigen. By using lym-phocyte hybridoma technique, a hybridoma cellline stably secreting monoclonal an-tibody against PCV2-rCap protein was successful y obtained and named as 670#. The ascites titer of the obtained monoclonal antibody was 1∶100 000. Western blot results showed that the monoclonal antibody could react with prokaryotical y ex-pressed PET32a-ORF2 recombinant protein, eukaryotical y expressed ORF1-ORF2 tandem protein and PCV2 whole virus celllysate. Indirect EILSA demonstrated that the monoclonal antibody could bind with ORF1-ORF2 tandem protein. Indirect im-munofluorescence assay （IFA） indicated that the monoclonal antibody could identify native PCV2 virus. The preparation of this monoclonal antibody provided technical tools for epitope analysis and molecular diagnosis of PCV2 virus.

A Comparative Study on Detection of the Expression of Alternative Oxidase in Tobacco Callus with the Monoclonal Antibody Against Alternative Oxidase and Antibody Against-Synthetic Polypeptide Antibody

从经过不同温度处理的烟草 (NicotianarusticaL .)愈伤组织中提取并纯化线粒体蛋白 ,分别与交替氧化酶的单克隆抗体和抗合成多肽抗体进行免疫杂交。结果表明 :交替氧化酶的含量随温度的下降而显著上升 ;单克隆抗体的特异性较高于抗合成多肽抗体 ,但后者与交替氧化酶同样有良好的亲和性。因此 ,用合成多肽方法制备的抗体可以用于交替氧化酶的研究中。

Preparation and Application of Monoclonal Antibodies Specific for Salicylic Acid

Salicylic acid (SA) is widely distributed in many monocots and dicots and has many physiological effects. It can induce heat production in the thermogenic inflorescences of Arum lily([1]), block the biosynthesis of ethylene, and more attractively, it seems to be an important natural signal molecule in the induction of systemic acquired resistance (SAR) in tobacco, cucumber and other plants([2,3]). Studies in recent years showed that SA was also intimately related to the resistance of plants to aboitic stress, for example, SA increased chilling resistance of maize seedlings. Hence, SA has been accepted as a kind of new plant hormones. Up to date, the quantification of SA usually has been performed by HPLC[4,5], which often needs a large quantity of sample and a verbose pretreatment. Compared to HPLC, immunoassays, including radio-immunoassays (RIA) and enzyme-immunoassays (EIA), are easy to perform and have been widely used in the quantification of other plant hormones, such as IAA([6]), ABA([7,8]), GAs([9]), cytokinins et al([10]), and jasmonic acid (JA)([11]), and other low-molecular-weight, none-immunogenic compounds in plants([12]). Till now, only an indirect enzyme-linked immunosorbent assay (ELISA) for SA based on polyclonal antibodies (PAbs) has been developed by our group([13]), although Bennett et al([14]) had prepared SA PAbs using 4-aminosalicylic acid linked to KLH as immunogen in goat. However, the sensitivity of the ELISA we established formerly was relatively low, and also relatively larger quantity of sample is needed than other ELISAs for plant hormones. In this paper, an ELISA for SA based on monoclonal antibody raised against SA-NH-CH2-NH-KLH was introduced, and the fluctuation of SA content in cucumber leaves after inoculated with Pseudomonas syringae pv. syringae was determined.

Preparation of Monoclonal Antibodies to Trimethoprim and ELISA Kit for Rapid Detection

[Objective] This study was conducted to find out an approach for determining trimethoprim residues in water. [Method] Trimethoprim antigen was prepared through a series of reactions from trimethoprim hapten which was generated through the reaction between trimethoprim and maleic anhydride. And trimethoprim monoclonal antibodies were prepared by animal immune, and used to prepare ELISA kit to detect trimethoprim residues in water. Finally, the limit of detection （LED） of the ELISA kit was determined. [Result] The standard curve covered a concentration range of 0-80 μg/L. The LeD of trimethoprim in water using the ELISA kit was 2.34 μg/kg; the IC50 （half maximal inhibitory concentration） was 4.8 μg/L; the recovery rate of added trimethoprim standard ranged from 60.5% to 79.7%; within-and among-batches RSD was less than 10%. The trimethoprim monoclonal antibody was specific, as the cross-reactivity rate of trimethoprim antibody and diaveridine was less than 1%. The stability tests revealed that the ELISA kit was stable after being stored at 4 ℃ for 12 months. [Conclusion] The results will provide references for controlling the abuse of trimethoprim.

PREPARATION AND CHARACTERIZATION OF TWO MONOCLONAL ANTIBODIES AGAINST A_α CHAIN'S C TERMINUS OF FIBRINOGEN

Two monoclonal antibodies (McAbs) against Aα chain's C terminus offibrinogen (Fg) have been prepared and designated SZ-78 and SZ-79. Both theantigens in binding assay and immunoblot analysis showed that the two McAbs recognized the epitopes located in residues 549-560 of the Aαchain. The two McAbs couldaccelerate rate of fibrin polymer assembly both in the purified system and in the humanplasma. From the pictures of transmission electronmicroscope, the average diametersof the fibers increase significantly to an average diameters of 375 nm after incubationwith the McAbs, while it was only 75nm without addition of the McAbs. There were al-so more branchings of fibers with addition of McAbs. These observations demonstratethat the amino acid sequences ofα 549-560 in the COOH terminus of the Aα chain mayplay an important role in the assembly of a fibrin clot, presumably being involved in lat-eral aggregation of protofibrils. The preparation of the McAbs supplies a usuful probe for the investigation of the

Preparation of Monoclonal Antibody against P65 Protein of Mycoplasma hyopneumoniae

P65 protein, the major immunodominant protein of Mycoplasma hyopneu-moniae （Mhp） exhibiting no cross-reaction with other mycoplasmas, is general y used as a target protein for Mhp detection. In this study, BALB/c mice were immunized with prokaryotical y expressed P65 recombinant protein to prepare monoclonal anti-body. After screening with Mhp whole-cel protein and P65 protein, a specific hy-bridoma cel line, 3G12, was obtained by ELISA. Identification results indicated that the antibody secreted by 3G12 hybridoma cel s could react with P65 protein and Mhp whole-cel protein. According to indirect ELISA assay, 3G12 cel culture super-natant possessed a titer of 1∶12 800 against P65 protein and 1∶3 200 against Mhp whole-cel protein; 3G12 ascites possessed a titer of above 1∶4 000 000 against P65 protein and above 1∶20 000 against Mhp 168 whole-cel protein. After long-term in vitro culture and continuous freezing-thawing, 3G12 cel line could stably secrete antibodies. A monoclonal antibody against P65 protein and Mhp whole-cel protein was successful y obtained in the present study, which provided basis for further in-vestigating the pathogenic mechanism of Mhp and establishing diagnostic methods of Mycoplasmal pneumonia of swine （MPS）.

Direct technetium-99m labeling of anti-hepatoma monoclonal antibody fragment:a radioimmunoconjugate for hepatocellular carcinoma imaging

AIM To directly radiolabel an anti-hepatomamAb fragment HAb18 F（ab’）2 with 99mTc bystannous-reduced method,and assess thestability,biodistribution and radioimmun-oimaging（RⅡ）.METHODS Immunoreactive fraction wasdetermined according to Lindmo’s method.Ellman’s reagent was used to determine thenumber of thiols in the reduced F（ab’）2.Labelingefficiency and homogeneity were measured bypaper chromatography,sodium dodecylsulphatepolyacrylamide gel electrophoresis（SDS-PAGE）and autoradiography.Challenge assay involvedthe incubation of aliquots of labeled antibody inethylenediaminetetraacetate（ EDTA ）and L-cysteine（L-cys）solutions with different molarratio at 37℃ for 1h,respectively.Investigationsin vivo utilized nude mice bearing humanhepatocellular carcinoma（HHCC）xenograftswith gamma camera imaging and tissuebiodistribution studies at regular intervals.RESULTS The labeling procedure was finishedwithin 1.5 h compared with the'pretinning'method which would take at least 21h.In vitrostudies demonstrated that the radiolabeled mAbfragment was homogeneous and retained itsimmunoreactivity.Challenge studies indicatedthat 99mTc-labeled HAb18 F（ab’）2 in EDTA is morestable than in L-cys.Imaging and biodistribution showed a significant tumor uptake at 24 h post-injection of 99mTc-labeled HAb18 F（ab’）2.Theblood,kidney,liver and tumor uptakes at 24hwere 0.56±0.09,56.45±11.36,1.43±0.27 and6.57±3.01（%ID/g）,respectively.CONCLUSION 99mTc-HAb18 F（ab’）2 conjugateprepared by this direct method appears to be aneffective way to detect hepatoma in nude micemodel.

Preparation and activity of conjugate of monoclonal antibody HAb18 against hepatoma F( ab′ )_2 fragment and staphylococcal enterotoxin A

AIM To prepare the conjugate of staphylococcal enterotoxin A (SEA) protein which is a bacterial SAg and the F(ab')2 fragment of mAb HAbl8 against human hepatocellular carcinoma (HCC), and identify its activity in order to use SAg in the targeting therapy of HCC.METHODS MAb HAbl8 was extracted from the abdominal dropsy of Balb/ c mice, and was purified through chromatography column SP-40HR with Fast protein liquid chromatography (FPLC) system. The F(ab')2 fragment of mAb HAb18 was prepared by papainic digestion method. The conjugate of mAb HAb18 F(ab')2fragment and SEA was prepared with chemical conjugating reagent N-succinimidyl-3-( 2-pyridyldithio) propionate (SPDP) and purified through chromatography column Superose 12with FPLC system. The molecular mass and purity of each collected peak were identified with SDS-PAGE assay. The protein content was assayed by Lowry's method. The antibody activity of HAb18 F (ab')2 against HCC in the conjugate was identified by indirect immunocytochemical ABC method, and the activity of SEA in the conjugate to activate peripheral blood mononuclear cells (PBMC) was identified with MTT assay.RESULTS The lgG mAb HAb18 was extracted,and purified successfully. Immunocytochemical staining demonstrated that it reacted with most of HHCC cells of human HCC cell line. There were two peaks in the process of purification of the prepared HAb18 F(ab)2-SEA conjugate. SDS-PAGE assay demonstrated that the molecular mass of the first peak was about 130 ku, and the second peak was the mixture of about 45 ku and a little 100 ku proteins. The immunocytochemical staining was similar in HAb18 F (ab ')2-SEAconjugate and HAb18 F (ab ')2, i.e., thecytoplasm and/or cell membranes of most HHCC cells were positively stained. The MTT assay showed that the optical absorbance (A) value at 490 nm of HAb18 F (ab')2-SEA conjugate was 0.182 ± 0.012, that of negative control was 0.033± 0.009, and there was significant difference between them ( P < 0.05).CONCLUSION SPDP is a good proteinconjugating reagent and can be used in preparing protein conjugate. The conjugate of mAb HAb18F(ab')2 fragment and SEA protein was preparedsuccessfully in present study and can be used in the experimental study of HCC targeting therapy with the conjugate of SAg and anti-HCC mAbs or their fragments.

Role of P-selectin and anti-P-selectin monoclonal antibody in apoptosis during hepatic/renal ischemia-reperfusion injury

AIM To evaluale the potential role of P-selectinand anti-P-selectin monoclonal antibody(mAb)in apoptosis during hepatic/renal ischemia-reperfusion injury.METHODS Plasma P-selectin level,hepatic/renal P-selectin expression and cell apoptosiswere detected in rat model of hepatic/ renalischemia-reperfusion injury.ELISA,immunohist-ochemistry and TUNEL were used.Someischemia-reperfusion rats were treated with anti-P-selectin mAb.RESULTS Hepatic/renal function insuffic-iency,up-regulated expression of P-selectin inplasma and hepatic/renal tissue,hepatic/renalhistopathological damages and cell apoptosiswere found in rats with hepatic/renal ischemia-reperfusion injury,while these changes becameless conspicuous in animals treated with anti-P-selectin mAb.CONCLUSION P-selectin might mediateneutrophil infiltration and cell apoptosis andcontribute to hepatic/renal ischemia-reperfusioninjury,anti-P-selectin mAb might be an efficientapproach for the prevention and treatment ofhepatic/renal ischemia-reperfusion injury.

Preparation and application of monoclonal antibodies against hepatitis C virus nonstructural proteins

AIM To prepare hybridoma cell lines which secrete anti HCV recombinant NS3 and NS5 proteins′ monoclonal antibodies, and to evaluate their usage in the study of the distribution of HCV NS3 and NS5 antigen in liver tissues. METHODS The hybridoma cell lines were raised using the spleen cells of BALB/C mouse immunized with recombinant NS3 and NS5 proteins according to the conventional protocols. The antibody secreting cells were screened using solid phase ELISA and cloned by limited dilution method. In order to determine the specificity of these hybridoma cell lines, the culture supernatant of these cells was western blot assayed with expression and nonexpresion E. coli and ELISA with other antigens, including HCV core and NS3 and HBsAg. Immunohistochemistry of 51 cases paraffin embedded liver tissues was performed to determine the distribution of HCV NS5 antigen as well as NS3 antigen in liver tissues. RESULTS Eight hybridoma cell lines secreting monoclonal antibodies against HCV NS3 and NS5 proteins were raised. They are named 2B6, 2F3, 3D8, 3D9, 8B2, 6F11, 4C6 and 7D9. Among them only 2B6 against NS3 protein can react with the polypipetides of C7 that is another recombinant polypipetides of NS3 gene. Others have no reaction with HCV core and HBsAg of HBV, and there is no cross reaction between NS3Ag and anti NS5Ag McAb and between NS5Ag and anti NS3 McAb. The immunohistochemistry results indicate that no HCV antigen was detected in the specimens of HBV infection in 20 cases. In 31 HCV infected specimens the positive rate of NS3Ag and NS5Ag are 51 6% (16/31) and 54 9% (17/31), respectively. There were six pure HCV infected specimens in these 31 specimens and half of them were HCV NS3Ag and NS5Ag positive. In the co infection of HBV and HCV group the positive rate of NS3Ag and NS5Ag were 52% (13/25) and 56% (14/25), respectively, almost the same with that of pure HCV infected group. The positive rates of HCV antigens were 70 6% (12/17) and 76 5% (13/17) in CAC patients. CONCLUSION The monoclonal antibodies we prepared are specific to the recombinant HCV NS3 and NS5 proteins and can be used in the clinical immunohistochemistry diagnosis.