Rheumatoid factor and falsely elevated results in commercial immunoassays: data from an early arthritis cohort

• DOI: 10.1007/s00296-021-04865-9
• Publication Date: 2021-05-04T06:03:02Z
• Authors: Johanna E. Gehin; Rolf A. Klaasen; Ellen S. Norli; David J. Warren; Silje W. Syversen; Guro L. Goll; Trine Bjøro; Tore K. Kvien; Maria D. Mjaavatten; Nils Bolstad
• Keywords: Rheumatoid factor

The aim of the study was to assess RF cross-reactivity animal antibodies used in immunoassays, and test if selected commercial immunoassays are vulnerable interference from RF, causing false results. Our included samples patients with RF-positive rheumatoid arthritis (RA) controls (patients RF-negative RA psoriatic arthritis), an early arthritis-cohort. Reactivity mouse IgG1, IgG2a, rabbit IgG, bovine sheep/goat IgG human analysed using in-house assays. sera strong reactivity IgG1 were three immunoassays. To reveal interference, results before after addition blocking aggregated murine compared. Samples 124 66 tested. We found considerably stronger toward antibodies, particularly (73% vs. 12%) (81% 6%), RA-patients compared (p < 0.001). After selecting for testing assays, revealed 6/30 Architect β-hCG assay, 7/10 27-plex cytokine 2/33 Elecsys Soluble Transferrin Receptor assay. considerable associated falsely elevated clinical care research. Clinicians, laboratorians, researchers assay manufacturers must be alert risk patients.