Summary of Invention Objective. The clinical diagnosis of Behçet's disease (BD) is difficult because the signs or symptoms of the disease vary widely and could overlap to the clinical manifestations of other autoimmune diseases. At the present there is no serodiagnostic test for BD. Aim of this study was to identify molecules specifically recognized by serum autoantibodies in BD patients. Methods. We screened a cDNA library from human microvascular endothelial cells (HMVEC) with IgG from the serum pool of two patients with BD.

We used enzyme-linked immunosorbent assay (ELISA) to measure specific IgG, IgM and IgA in patients with BD, systemic lupus erythematosus, scleroderma and in healthy subjects. Results. Immunoscreening of the HMVEC expression library identified one clone with a amino acid sequence 100% identical to the C-terminal subunit of the splicing factor Sip 1. IgG specific to Sip 1 were present in 11/56 (20%) BD patients, IgM in 23/56 (41%) and IgA in 9/54 (17%). IgM-ELISA to Sip1 had a specificity and positive predictive value of 100%. IgM immunoreactivity to Sip1 was significantly higher in patients with BD than in those with SLE, scleroderma and in healthy subjects (0.09±0.07 vs 0.03±0.03, 0.02±0.02 and 0.03±0.03, respectively, P

Priority Filing in Italy on July 27 2005.

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