Immunometric Assay Interference: Incidence and Prevention

• Published in: Clinical chemistry (Baltimore, Md.) Md.), 2002, Vol.48 (4), p.613-621
• Main Authors: Bjerner, Johan, Nustad, Kjell, Norum, Lars F, Olsen, Kari Hauge, Bormer, Ole P
• Format: Article
• Language: English
• Subjects: Animals; Antibodies, Monoclonal; Biological and medical sciences; Buffers; Carcinoembryonic Antigen - analysis; Cattle; False Positive Reactions; Hot Temperature; Humans; Immunoassay - standards; Immunoglobulin Fc Fragments; Immunoglobulin G; Immunoglobulins; Investigative techniques, diagnostic techniques (general aspects); Medical sciences; Mice; Miscellaneous. Technology; Pathology. Cytology. Biochemistry. Spectrometry. Miscellaneous investigative techniques; Quality Control
• ISSN: 0009-9147; 1530-8561

The primary aim of the study was to reduce interference in an in-house two-site, two-step immunometric assay. In the running laboratory routine, 11 261 samples were tested with a carcinoembryonic antigen (CEA) assay with bovine immunoglobulin but no murine immunoglobulins in the buffer, in parallel to our routine CEA assay, using 15 mg/L heat-treated nonspecific murine immunoglobulin (MAK33) in the buffer and with the Fc fragments removed from the capture antibody. The frequency of interference was estimated to be 4.0% (95% confidence interval, 3.3-4.7%). The addition of 15 mg/L native MAK33 had little effect (frequency, 3.9%; 95% confidence interval, 3.2-4.6%), whereas adding 15 mg/L heat-treated MAK33 reduced interference to 0.86% (0.61-1.12%), and adding 50 mg/L reduced it further to 0.06% (0-0.13%). Removing the Fc fragments by itself reduced interference to 0.10% (0.02-0.19%). There were no statistically significant differences for age (P