OBJECTIVETo develop a more reliable and stable method for determining monoclonal antibody (mAb) affinity constant based on competitive antibody/antigen binding.

METHODSThe Kd value was calculated based on the relationship between the binding proportion of the antigen and the original concentration of the mAb that competed for the binding site of the antigen.

RESULTSThe Kd values measured with this improved method under two different conditions were 2.61x10(-12) mol/L and 2.39x10(-12) mol/L, and those with Friguent method in these two conditions were 5.57x10(-10) mol/L and 1.41x10(-10) mol/L, respectively.

CONCLUSIONCompared with Friguent method, the Kd values measured with this improved method are closer to the actual value, and the measurement results under different experiment conditions are more stable.

Antibodies, Monoclonal ; immunology ; Antibody Affinity ; immunology ; Antigen-Antibody Complex ; immunology ; Binding, Competitive ; Enzyme-Linked Immunosorbent Assay ; Humans

OBJECTIVESTo obtain a single-chain antibody with high affinity against hepatocellular carcinoma (HCC).

METHODSA second single-chain antibody mutant library was established using an error-prone PCR and a phage display. Single-chain antibodies with high affinity for hepatocellular carcinoma were selected using ELISA.

RESULTSThe content of the second single-chain antibody mutant library was about 4.5 x 10(7). Two selected mutants, M90 and M116, were obtained after 3 rounds of panning and ELISA. Immunoassay showed that both M90 and M116 could bind to human HCC cells. The relative affinity of M90 was 1.7-fold higher than that of the original antibody, and M116 was 2-fold higher than that of the original antibody.

CONCLUSIONError-prone PCR is an effective and simple method for affinity maturation of antibodies isolated from a phage antibody library.

Antibodies, Neoplasm ; immunology ; Antibody Affinity ; Antibody Specificity ; Carcinoma, Hepatocellular ; immunology ; pathology ; Humans ; Immunoglobulin Fragments ; immunology ; Immunoglobulin Variable Region ; genetics ; immunology ; Liver Neoplasms ; immunology ; pathology ; Mutation ; Peptide Library

Oxidized low density lipoprotein (LDL) seems to take a part in atherogenesis through direct interactions with macrophages, endothelial cells, and smooth muscle cells, and is thought to participate in renal glomerular injury. For the purpose of illustrating the role of oxidized LDL in the human diseases, monoclonal antibodies were developed and characterized, recognizing oxidized LDL-specific epitopes that do not exist on native LDL. LDL was oxidized by the incubation with CuSO4, and used as immunogen. Splenocytes from the immunized mouse and mouse myeloma cells were fused to produce hybridomas, which were screened for the secretion of oxidized LDL-specific antibodies. Immunoblot analysis and binding affinity assay showed that these monoclonal antibodies recognize malondialdehyde-conjugated peptide epitopes.
Antibodies, Monoclonal ; Antibody Affinity ; Antibody Specificity ; Enzyme-Linked Immunosorbent Assay ; Epitopes ; Human ; Lipoproteins, LDL/immunology* ; Malondialdehyde/immunology ; Malondialdehyde/analysis ; Peptide Fragments/immunology ; Thiobarbituric Acid Reactive Substances/analysis

OBJECTIVEScreening and characterizing high affinity completely humanized single-chain antibody (ScFv) against PreS1 of hepatitis B virus.

METHODSA combinatorial library of phage-displayed human ScFv, genes of which were derived from peripheral blood lymphocytes immunized by PreS1 of Hepatitis B Virus in vitro, was constructed. The library contained 7 10(8) clones.

RESULTSAfter 3 rounds panning, a high affinity (K=10(7) to 10(8) mol/L) ScFv specific to PreS1 was obtained. The V(H) belonged to human V(H4) family, and V(1) to V(4) by sequence analysis.

CONCLUSIONThis study suggests that the method of antigen stimulation in vitro is an expeditious way for the source of human immune antibody. And the ScFv may provide a more satisfactory therapy.

Antibodies, Monoclonal ; biosynthesis ; Antibody Affinity ; Hepatitis B Antibodies ; biosynthesis ; Hepatitis B Surface Antigens ; immunology ; Humans ; Peptide Library ; Protein Precursors ; immunology

OBJECTIVETo evaluate the in vitro and in vivo function of anti-human bladder tumor human-mouse chimeric antibody ch-BDI and its future clinical application.

METHODSWith ch-BDI in high-expression cell-line medium, affinity chromatography was used for the purification. Labeled with (99m)Tc through reduction method, its immunoreactive fraction and association constant were measured. The constant was injected into nude mice with xenografted human bladder tumor. The biodistribution of the labeled ch-BDI was studied with radioimmunoimaging.

RESULTSch-BDI showed desirable immunoreactive fraction (76%) and association constant (3.56 x 10(9) M(-1)) in vitro and a terrific specific targeting effect in vivo.

CONCLUSIONch-BDI has fairly good function against human bladder tumor both in vitro and in vivo, and is promising in clinical use.

Animals ; Antibodies, Monoclonal ; immunology ; Antibodies, Neoplasm ; immunology ; Antibody Affinity ; Humans ; In Vitro Techniques ; Mice ; Mice, Inbred BALB C ; Mice, Nude ; Recombinant Fusion Proteins ; immunology ; Urinary Bladder Neoplasms ; immunology

Antibodies, Monoclonal ; pharmacology ; therapeutic use ; Antibodies, Neoplasm ; immunology ; therapeutic use ; Antibody Affinity ; Antibody Specificity ; Antigen-Antibody Reactions ; Antigens, Neoplasm ; analysis ; immunology ; Carcinoma, Hepatocellular ; immunology ; therapy ; Humans ; Liver Neoplasms ; immunology ; therapy

OBJECTIVETo identify the self-preparation monoclonal antibody which target to clenbuterol, and set up the standard curve to clenbuterol (CL) detection.

METHODSThe affinity constants and activity of the monoclonal antibody which target to CL were determined by ELISA. ELISA was also used to confirm whether the monoclonal antibody had any across-reaction with BSA and CL analogues. The rat ascites which contains the monoclonal antibody target to CL was purified by (NH4)2SO4 salt-out method and further by affinity column. At last, the CL detection standard curve which based on indirect competition ELISA was established.

RESULTSThe ELISA experiment showed that the antibody titer was 10(6) and the monoclonal antibody affinity constants was 2.90 x 10(10) L/mol. The result of the indirect competition ELISA confirmed that the monoclonal antibody had no cross-reaction with BSA and a few kind of CL analogue. CL detection standard curve based on indirect competition ELISA was established, which R2 was 0.9812, and the lowest detectable limit was 1.0 ng/ml.

CONCLUSIONThe standard curve based on indirectly competitioning ELISA was established. The self-preparation monoclonal antibody which target to CL has high affinity and high specific to CL, which had established the foundation to the advanced development of the CL immune test paper and CL ELISA kit.

Animals ; Antibodies, Monoclonal ; chemistry ; isolation & purification ; Antibody Affinity ; Clenbuterol ; immunology ; Cross Reactions ; Enzyme-Linked Immunosorbent Assay ; Limit of Detection ; Rats

AIMTo synthesize and identify artificial antigen of podophyllotoxin for the production of podophyllotoxin polyclonal antibody.

METHODSThe hapten was synthesized by two different chemical approaches and characterized by TLC, IR, NMR, and MS. Mixed anhydride reaction (MAR) and active ester method (AEM) were used to couple the podophyllotoxin to carrier proteins (BSA and OVA). Characterization of artificial antigens was done by using spectroscopy and electrophoresis. The anti-podophyllotoxin polyclonal antibodies were obtained through immunizing rabbits.

RESULTSThe results from IR, NMR and MS showed that 4-O-succinoyl podophyllotoxin (hapten) was successfully synthesized. The coupling molar ratios of the hapten and carrier proteins were 88.6 for Hapten-BSA1, 40.3 for Hapten-BSA2, 17.8 for Hapten-OVA1, and 54.2 for Hapten-OVA2. Hapten conjugates coupled with BSA yielded two sets of the specific and affinitive polyclonal antibodies. One set of antibodies showed an IC50 value of 2.21 microg.mL(-1) with a detection limit of 0.12 microg.mL(-1).

CONCLUSIONAntigenic conjugates were artificially synthesized, and based on these artificial antigens, polyclonal antibodies against podophyllotoxin were raised from rabbits immunized with two different immunogens and characterized with an indirect ELISA format.

Animals ; Antibodies ; analysis ; Antibody Affinity ; Antibody Formation ; Antineoplastic Agents, Phytogenic ; immunology ; Enzyme-Linked Immunosorbent Assay ; Haptens ; chemistry ; immunology ; Immune Sera ; chemistry ; Male ; Ovalbumin ; immunology ; Podophyllotoxin ; immunology ; Proteins ; immunology ; Rabbits ; Serum Albumin, Bovine ; immunology

We prepared two monoclonal antibodies-A-I30 and A-I4 to HDL apo A-I-with the ultimate goals of expressing and overproducing the valuable immunodiagnostic single chain Fv by phage display libraries in E, coli. Monoclonal antibodies were produced by immunizing mice with apolipoprotein A-I, and purified from ascitic fluid by affinity chromatography on a Protein A Sepharose CL-4B column. The specificity of A-I30 and A-I4 was confirmed by ELISA and Western blotting. The dissociation constants(Kd) of antigen-antibody complex obtained by enzyme linked immunosorbent assay(ELISA) method were 2.25 x 10(-8) M for A-I30 and 2.15 x 10(-8) M for A-I4. The experimental values of Kd are shown to be close to those obtained by immunoprecipitation of the radiolabeled antigen. From the above results, it was shown that A-I30 and A-I4 could be provided as excellent reagents for the determination of plasma HDL concentrations in clinical specimens using ELISA.
Animal ; Antibodies, Monoclonal/*immunology/isolation & purification ; Antibody Affinity ; Apolipoprotein A-I/*immunology ; Blotting, Western ; Hybridomas ; Lipoproteins, HDL/immunology ; Mice ; Mice, Inbred BALB C ; Tumor Cells, Cultured

OBJECTIVETo produce anti-19-Nortestosterone (NT) monoclonal antibodies and identify their immunological characteristics.

METHODSHybridomas were prepared by fusing NS0 mouse myeloma cells with splenocytes isolated from immunized BALB/c mice. Noncompetitive and competitive indirect ELISA were employed to screen positive cell clones. A caprylic acid ammonium sulphate (CAAP) method was used to purify NT mAb, and the Batty saturation method was used to determine the affinity constant (Kaff).

RESULTSFive hybridoma cell lines, named NT-1, NT-2, NT-3, NT-4, and NT-5, were identified and their corresponding mAbs were of the IgG(1) isotype with a k light chain. The Kaffs of all mAbs were between 2.6 and 4.7 × 10(9) L/mol. The titers and IC(50) values of purified ascite fluids were in the range of (0.64-2.56) × 10(5) and (0.55-1.0) ng/mL, respectively. Of all the cross-reacting steroids, (-NT was the most reactive with the mAbs at 62% with NT-1 mAb and 64% with NT-2 mAb. Negligible cross-reactivity (<0.01%) with other steroids was observed.

CONCLUSIONThe establishment of these hybridomas allows the potential development of a rapid test kit, and may provide an alternative method for the detection of NT residues in food producing animals.

Animals ; Antibodies, Monoclonal ; Antibody Affinity ; Antibody Specificity ; Cell Line ; Female ; Hybridomas ; Mice ; Mice, Inbred BALB C ; Molecular Structure ; Nandrolone ; chemistry ; immunology ; Plasmacytoma ; Reagent Kits, Diagnostic ; Spleen ; cytology