False Positive Results in SARS-CoV-2 Serological Tests for Samples From Patients With Chronic Inflammatory Diseases

Abstract

Patients with chronic inflammatory diseases are often treated with immunosuppressants and therefore are of particular concern during the SARS-CoV-2 pandemic. Serological tests will improve our understanding of the infection and immunity in this population, unless they tests give false positive results. The aim of this study was to evaluate the specificity of SARS-Cov-2 serological assays using samples from patients with chronic inflammatory diseases collected prior to April 2019, thus defined as negative. Samples from patients with multiple sclerosis (MS, n=10), rheumatoid arthritis (RA, n=47) with or without rheumatoid factor (RF) and/or anti-cyclic citrullinated peptide antibodies (anti-CCP2) and systemic lupus erythematosus (SLE, n=10) with or without RF, were analyzed for SARS-CoV-2 antibodies using 17 commercially available lateral flow assays (LFA), two ELISA kits and one in-house developed IgG multiplex bead-based assay. Six LFA and the in-house validated IgG assay correctly produced negative results for all samples. However, the majority of assays (n=13), gave false positive signal for samples from patients with RA and SLE. This was most notable in samples from RF positive RA patients. No false positive samples were detected in any assay using samples from patients with MS. Poor specificity of commercial serological assays could possibly be, at least partly, due to interfering antibodies in samples from patients with chronic inflammatory diseases. For these patients, the risk of false positivity should be considered when interpreting results of the SARS-CoV-2 serological assays.

SARS-CoV-2 Antibody Isotypes in Systemic Lupus Erythematosus Patients Prior to Vaccination: Associations With Disease Activity, Antinuclear Antibodies, and Immunomodulatory Drugs During the First Year of the Pandemic

“…Presence of rheumatoid factor often challenges the specificity of immunoassays and is, in general, a common suspect of false positive tests. This was recently highlighted also for different immunoassays of serological SARS-CoV-2 testing in patients with chronic inflammatory diseases, whereof most of the investigated samples originated from patients with MS and RA (47). A subgroup of rituximab-treated SLE patients was included, but rheumatoid factor did not seem to have a major impact on the SARS-CoV-2 test results in SLE.…”

Microarray-Based Detection of Antibodies against SARS-CoV-2 Proteins, Common Respiratory Viruses and Type I Interferons

“…To our knowledge, this is the first study to evaluate the specificity of SARS-CoV-2 antibody tests in a group of patients with autoimmune endocrine disorders. Kharlamova et al have recently shown a high false-positive rate when analyzing prepandemic samples of patients with chronic inflammatory diseases (multiple sclerosis, rheumatoid arthritis and systemic lupus erythematosus) using commercial serological tests [40]. Positive SARS-CoV-2 antibody test results in naive populations have previously been identified in stored prepandemic sera [13], and uninfected individuals [41].…”

Immunoaffinity Capillary Electrophoresis in the Era of Proteoforms, Liquid Biopsy and Preventive Medicine: A Potential Impact in the Diagnosis and Monitoring of Disease Progression

“…For most part, enzyme-linked immunosorbent assay (ELISA), immunohistochemistry (IHC) and flow cytometer assays in particular are immunoassays routinely found in diagnostic laboratories. ELISA continues to be the gold standard for biomarker detection [117][118][119][120][121][122][123] because of its high precision, throughput, and sensitivity (In clinical diagnostic chemistry, a sensitive test refers to a test that will correctly identify almost all individuals who likely have a disease, and will rarely yield a false negative result. A specific test refers to a test that will almost always correctly rule out those who do not have a disease, and will rarely yield a false positive result [117].…”

“…In analytical chemistry, sensitivity is the minimal detectable concentration of an analyte, expressed as the limit of detection (LoD), that can be accurately measured.). While the last two decades has seen tremendous innovation in ELISA technology, including automation with robotic workstations, improved microtiter plate readers, higher throughput well formats, and better antibody immobilization techniques, it has not been able to overcome for several reasons [119][120][121][122][123] limitations of diagnostic sensitivity [117] and specificity (Specificity is the ability to accurately assess a single analyte in the presence of components which may be expected to be present in the sample matrix, such as interferences. Similar to specificity, selectivity is the ability to accurately separate out and assess multiple components present in a sample mixture or matrix [119]).…”

“…To avoid confusion when referring to affinity capillary electrophoresis, we have defined the terminology as free-solution affinity capillary electrophoresis (FSACE) to the two methods of affinity capillary electrophoresis whose interactions are carried out in solution, and immobilized affinity capillary electrophoresis or immunoaffinity capillary electrophoresis (IACE) when the ligand or probes are immobilized to a surface within a portion of the capillary or channel. However, IACE not only uses antibodies or antibody fragments as highly selective capture agents, but also other biorecognition affinity reagents can act as ligands or probes, such as lectins, aptamers, metal-organic and other substances that have affinity for other analytes [122,[174][175][176][177][178][179][180][191][192][193][194][195][196][197][198][199][200][201][202][203].…”