RT Journal Article
SR Electronic
T1 Beware of Antibodies to Dietary Proteins in “Antigen-specific” Immunoassays! Falsely Positive Anticytokine Antibody Tests Due to Reactivity with Bovine Serum Albumin in Rheumatoid Arthritis (The Swedish TIRA Project)
JF The Journal of Rheumatology
JO J Rheumatol
FD The Journal of Rheumatology
SP 215
OP 220
DO 10.3899/jrheum.100690
VO 38
IS 2
A1 CHRISTOPHER SJÖWALL
A1 ALF KASTBOM
A1 GUNNEL ALMROTH
A1 JONAS WETTERÖ
A1 THOMAS SKOGH
YR 2011
UL http://www.jrheum.org/content/38/2/215.abstract
AB Objective. To evaluate (1) to what extent sera from healthy subjects and patients with rheumatoid arthritis (RA) contain antibodies to bovine serum albumin (BSA); and (2) if anti-BSA antibodies interfere with results of enzyme-linked immunoassays (ELISA) containing BSA. Methods. The ELISA used was a previously developed in-house assay of autoantibodies to tumor necrosis factor (TNF). Anti-TNF and anti-BSA antibodies were analyzed by ELISA in 189 patients with early RA and 186 healthy blood donors. TNF preparations containing either BSA or human serum albumin (HSA) as carrier proteins were used as antigens in the anti-TNF assay. The presence and levels of antibodies were analyzed in relation to disease course and to the presence/absence of rheumatoid factor (RF). Results. In patients with RA, anti-TNF/BSA levels strongly correlated with anti-BSA levels (r = 0.81, p < 0.001), whereas anti-TNF/HSA did not (r = −0.09). Neither the presence nor the levels of anti-BSA in RA patients were associated with disease progression, and antibody levels were not significantly altered compared to controls (p = 0.11). IgG reactivity with TNF/HSA was neglible. In paired sera, preincubation with BSA abolished the anti-TNF/BSA reactivity. There were no indications of RF interference with anti-BSA or anti-TNF reactivity. Conclusion. Antibodies to BSA are common in patients with RA as well as in healthy individuals. Their presence does not seem to be associated with RA disease activity or disease course, but may severely interfere with ELISA containing BSA. The use of BSA as a “blocking agent” or carrier protein in immunoassays should therefore be avoided.