Techniques for Identifying Heterophile Antibody Interference Are Assay Specific: Study of Seven Analytes on Two Automated Immunoassay Analyzers

Interference by human anti-animal immunoglobulins, commonly referred to as heterophile antibodies, in immunologic assays is known to be an important consideration for medical testing laboratories (1)(2)(3). Although automated immunometric assays are formulated to reduce these effects, it is unlikely that complete elimination occurs (2), and artifactual results attributable to heterophile antibodies have been reported for some assays (4)(5). Such results often are identified by addition of blocking agents to the samples before assay. A simple sample pretreatment method uses a commercially available blocking tube, HBT. An alternative technique uses polyethylene glycol (PEG) to precipitate immunoglobulin-sized molecules before assay. For both of these techniques, a difference between values for the treated and untreated specimens is interpreted as evidence for heterophile antibody interference.It is not clear that either of these methods is appropriate for every immunoassay. It is important to know the effect of sample pretreatment on the results of each assay. This has been done recently for HBT and a thyroglobulin assay (4). We examined seven automated analyzer hormone assays, using pretreatments with both HBT and PEG of samples from healthy adults, with the aim of determining the expected change in results post treatment for both techniques for each assay.We investigated luteinizing hormone (LH), follicle-stimulating hormone (FSH), prolactin (PRL), and growth hormone (GH) on the Access2 analyzer and insulin, parathyroid hormone (PTH), and cross-linked C-terminal telopeptide of type I collagen (β-CTx; β CrossLaps) on the Elecsys analyzer. Analyzer reagents and consumables were obtained from Beckman-Coulter and Roche Diagnostics, respectively. Plasma (EDTA) samples were collected from healthy individuals in a study approved by the …