Screening for specific biomarkers in patients with seronegative primary Sj？gren′s syndrome using an immunoproteomic approach

Objective To identify proteomic biomarkers in serum samples and to construct a pro-teomic model for diagnosis of anti-SSA and anti-SSB negative primary Sj？gren′s syndrome （ pSS） .Methods Serum proteomic spectra were generated by using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry （MALDI-TOF-MS） in combination with weak cation exchange （WCX） magnetic beads. The proteomic data were analyzed by Ciphergen ProteinChip and BioMarker Wizard software .The protein peaks were further analyzed by Biomarker Patterns Software to screen the representative proteomic biomark -ers, which were to be used to construct a decision tree model for the diagnosis of anti -SSA and anti-SSB neg-ative pSS.Results Ten mass-to-charge （m/z） peaks with significant difference were identified among sub-jects with antibody-negative pSS and antibody-positive pSS （P〈0.05）.Among them, the protein peaks with the m/z value of 6625 .004 and 27993 .280 were selected as potential biomarkers to construct the diag-nostic decision tree model .The sensitivity and specificity of the model were 77.8%and 90.9%respectively as indicated by a double blind study .Conclusion The potential protein biomarkers for seronegative pSS could be identified by MALDI-TOF-MS in combination with WCX magnetic beads .A proteomic model for the diagnosis of seronegative pSS was successfully constructed with an advantage of good sensibility and specifici -ty based on the protein peaks with m/z value of 6625 .004 and 27993 .280 . Key words: Sj？gren′s syndrome; Autoantibody; Seronegative; Proteomics