A simple and sensitive assay for determination of human anti-idiotypic anti-B72.3 antibodies, which is not affected by the presence of tumour-associated glycoprotein 72.
An immunoradiometric assay is described for the determination of human anti-idiotypic anti-B72.3 IgG. The latter is formed in ovarian cancer patients after treatment with the murine monoclonal antibody B72.3, which is directed against the tumour-associated glycoprotein 72 (TAG-72). A gel coupled with Fc-specific anti-human IgG antibodies is used as a solid phase for the extraction of serum IgG. The anti-B72.3 IgG is then specifically detected by incubation with radiolabelled B72.3 detector antibodies. Calibration standards were prepared from serum obtained from a patient repeatedly treated with B72.3 antibodies. The concentration of anti-idiotypic anti-B72.3 antibodies was expressed as TAG-72-like arb.units/1. The assay performed with two 60-minute incubation steps is characterized by a high sensitivity (detection limit: 3 x 10(3) arb.units/1) and precision (coefficients of variation: intra-assay = 6.4% and 5.8% at 80 x 10(3) arb. units/1 and 217 x 10(3) arb.units/1, inter-assay = 8.7% and 7.1% at 91 x 10(3) arb.units/1 and 212 x 10(3) arb.units/1) and a good linearity of dilution (recovery after dilution between 99% and 107%). The assay is more specific than previously described methods; no interference was observed by TAG-72 up to 3.3 x 10(7) arb.units/1. Also, non-specific human anti-mouse antibodies did not cross-react up to 34.8 mg/l. The test may be modified for detection of anti-idiotypic antibodies, which are formed after treatment with other monoclonal antibodies.
Reinsberg
J
J
Zentrum für Frauenheilkunde und Geburtshilfe, Universität Bonn, Germany.
Schmolling
J
J
Ackermann
D
D
D000818:Animals; D000888:Antibodies, Anti-Idiotypic / Q000097:blood* / Q000276:immunology / Q000378:metabolism; D000911:Antibodies, Monoclonal / Q000627:therapeutic use; D000918:Antibody Specificity; D000937:Antigen-Antibody Reactions / Q000187:drug effects; D000951:Antigens, Neoplasm / Q000097:blood* / Q000276:immunology / Q000378:metabolism; D002138:Calibration; D003429:Cross Reactions; D005260:Female; D005782:Gels; D006023:Glycoproteins / Q000097:blood* / Q000276:immunology / Q000378:metabolism; D006801:Humans; D005779:Immunodiffusion; D007074:Immunoglobulin G / Q000097:blood* / Q000276:immunology / Q000378:metabolism; D015592:Immunoradiometric Assay; D051379:Mice; D010051:Ovarian Neoplasms / Q000097:blood / Q000276:immunology / Q000628:therapy; D015203:Reproducibility of Results
D000888:Antibodies, Anti-Idiotypic; D000911:Antibodies, Monoclonal; D000951:Antigens, Neoplasm; D005782:Gels; D006023:Glycoproteins; D007074:Immunoglobulin G; C047052:tumor-associated antigen 72