title: Autoantibodies to C-reactive protein is a common finding in SLE, but not in primary Sjögren's syndrome, rheumatoid arthritis or inflammatory bowel disease.
abstract: The occurrence of antibodies to human C-reactive protein (CRP) was analysed by enzyme-linked immunosorbent assay (ELISA) in 56 patient sera known to contain antibodies to double-stranded DNA (dsDNA) and in 16 sera from patients with primary Sjögren's syndrome (SS), 15 rheumatoid arthritis, 31 Crohn's disease, and 37 ulcerative colitis. Eighty-seven per cent of the patients with anti-dsDNA antibodies had systemic lupus erythematosus (SLE) and the remaining had autoimmune hepatitis. The cut-off for positive anti-CRP test was set at the 95th percentile of 100 healthy blood donors. Twenty of 56 anti-dsDNA sera (36%) and two of 16 SS sera (13%) had antibodies reactive with human CRP, whereas all other samples were negative. Thirteen of 27 SLE patients (48%) were positive on at least one occasion. The sera containing anti-CRP antibodies only reacted with surface-bound antigen, but not with native CRP in solution. In conclusion, we found that autoantibodies to CRP are common in sera from patients with anti-dsDNA antibodies. It is not likely that this explains the relative failure of CRP response in patients with active SLE. However, it cannot be excluded that anti-CRP autoantibodies have other biological potentials of pathophysiological interest in SLE, for instance by binding to CRP deposited on cell and tissue surfaces.
authors.affiliation: Department of Molecular and Clinical Medicine, Division of Rheumatology, Faculty of Health Sciences, University of Linköping, S-581 85 Linköping, Sweden. chrsj467@student.liu.se
authors.forename: Christopher
authors.initials: C
authors.lastname: Sjöwall
authors.forename: Per
authors.initials: P
authors.lastname: Eriksson
authors.forename: Sven
authors.initials: S
authors.lastname: Almer
authors.forename: Thomas
authors.initials: T
authors.lastname: Skogh
mesh_terms: D000328:Adult; D000818:Animals; D000918:Antibody Specificity; D001172:Arthritis, Rheumatoid / Q000276:immunology; D001323:Autoantibodies / Q000276:immunology*; D002097:C-Reactive Protein / Q000276:immunology*; D005260:Female; D006801:Humans; D015212:Inflammatory Bowel Diseases / Q000276:immunology; D008180:Lupus Erythematosus, Systemic / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D011817:Rabbits; D012859:Sjogren's Syndrome / Q000276:immunology*
chemical_list: D001323:Autoantibodies; D002097:C-Reactive Protein