Diagnostic value of anti-MCV antibodies for ankylosing spondylitis

Abstract

Objective To investigate the diagnostic value of anti-mutated citrullinated vimentin（anti-MCV） and anti-cyclic citrullinated peptide（anti-CCP） antibodies for ankylosing spondylitis (AS), and to establish a new diagnostic method of AS based on anti-citrullinated protein/peptide antibodies（ACPAs） detection. Methods Totally 121 AS patients(AS group), 97 rheumatoid arthritis（RA） patients(RA group)and 103 healthy people(control group) were enrolled for the detection of serum levels of anti-MCV and anti-CCP antibodies using ELISA method as a diagnostic test. HLA-B27 in AS patients was tested by flow cytometry, and RF-IgM in RA and AS patients was detected by immune rate nephelometry. Receiver operating characteristics (ROC) curve was used to analyze the diagnostic value and to determine the cut-off value. Anti-MCV and anti-CCP antibodies among each group were compared by Mann-Whitney U test, Chi-square test or Fisher′s exact test was used to compare positive rate. Results The anti-MCV levels in AS group ［11.60 (12.36-25.83) U/ml］were significantly higher than control group ［11.60(8.41-13.54）U/ml ］,U=2 413,P<0.001, while the levels of anti-CCP had no difference between the two groups ［AS group 6.22 （4.30-8.07）U/ml］, and control group ［6.01(3.77-7.58)U/ml］, respectively; U=5 421,P=0.094. The calculated area under the ROC curve of anti-MCV was 0.806,and 14.67 U/ml was the optimal cut-off value with sensitivity of 0.645 and specificity of 0.942. In both HLA-B27 positive and negative AS patients, anti-MCV antibodies levels and positive rate were significantly higher than control group using new cut-off value above （U=133.5, P=0.001; U=2 279.5,P<0.001). Sensitivity of the combination detection of anti-MCV and anti-CCP (MCV+CCP－) or RF-IgM (MCV+RF－) were 60.3% (73/121), 62.8% (76/121) and specificity were 89.7% (87/97), 90.7% (88/97) respectively in differential diagnosis of AS and RA, which were significantly higher than anti-MCV detection alone in specificity (16.5%,16/97). Conclusions Anti-MCV could be a new biomarker for the diagnosis of AS. With high sensitivity and specificity, anti-MCV has an equal diagnostic efficiency in HLA-B27 positive and negative AS patients using our new cut-off value. Additionally， the combination detection of anti-MCV and anti-CCP or RF-IgM could be an effective method for differential diagnosis of AS and RA.（Chin J Lab Med,2014,37: 455-458） Key words: Spondylitis,ankylosing; Peptides,cyclic; Vimentin; Mutation; Rheumatoid factor