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High serum levels of antibodies against the recombinant 70 kDa ribonucleoprotein are useful for diagnosing mixed connective tissue disease
Author(s) -
Salmhofer W,
Hermann J,
Joch M,
Kerl H,
Graninger W
Publication year - 2007
Publication title -
journal of the european academy of dermatology and venereology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.655
H-Index - 107
eISSN - 1468-3083
pISSN - 0926-9959
DOI - 10.1111/j.1468-3083.2007.02163.x
Subject(s) - mixed connective tissue disease , medicine , antibody , antigen , autoantibody , immunology , ribonucleoprotein , small nuclear ribonucleoprotein , connective tissue disease , extractable nuclear antigens , connective tissue , recombinant dna , anti nuclear antibody , autoimmune disease , pathology , biology , rna , biochemistry , gene
Background Anti‐Sm antibodies and anti‐RNP antibodies are considered to be diagnostic markers of systemic lupus erythematosus (SLE) and mixed connective tissue disease (MCTD). However, cross‐reactivity between the antibodies diminishes their discriminating specificity between these diagnoses. Objective We examined whether we could achieve better differentiation between these two disease entities using recombinant antigens to RNP70 and SmD and quantitative immunoassays. Patients/methods Sera from 51 patients with SLE and 10 patients with MCTD and from a control group of 59 patients were used in a cross‐sectional setting. Semiquantitative ELISAs for the detection of antibodies to RNP‐70, RNP‐A, RNP‐C, SmBB′ and SmD were used and the results were compared to conventional ELISA tests using U 1 ‐snRNP and a mixture of SmBB′ and SmD as antigenic substrates. Results Sera from MCTD patients showed higher levels of anti‐RNP‐70 antibodies than sera from SLE patients. Levels of anti‐SmBB′ or anti‐SmD antibodies were not significantly different between SLE and MCTD sera. However, the presence of antibodies directed against SmD was more frequent in SLE. Conclusions Our results suggest that the use of RNP‐70 and SmD antigens may increase the practical value of immunoassays used to confirm a diagnosis of SLE or MCTD in patients with connective tissue disease.