Antikinectin autoantibody in Behçet's disease and several other autoimmune connective tissue diseases

Antikinectin autoantibody has recently been identified as a potential biomarker in Behçet's disease (BD). Here, we established an enzyme-linked immunosorbent assay (ELISA) and an indirect immunofluorescent assay (IFA) for detecting this antibody. The clinical significance of antikinectin was investigated.

Partial or full-length cloning for human kinectin in prokaryotic or eukaryotic system was carried out. Three fragments covered kinectin coding sequence were used to establish ELISA. Full-length kinectin overexpressed HepG2 cells were used as a substrate for IFA. Serum samples from BD (n = 46), systemic lupus erythematosus SLE, n = 16), rheumatoid arthritis (RA, n = 160, ankylosing spondylitis (AS, n = 14), primary Sjörgen syndrome (pSS, n = 12), mixed connective tissue disease (MCTD, n = 8), and healthy donors (n = 51) were examined.

Good measurement consistency between IFA and ELISA (p < 0.001) and previous immunoprecipitation assay (p = 0.011) was found. Antikinectin was found not only in 32.6% (IFA) to 41.3% (ELISA) BD patients but was also identified in pSS, SLE, MCTD, and RA with prevalence ranging from 12.5% to 25%. Nevertheless, the titer of antikinectin (ELISA) is statistically higher in BD compared to other autoimmune connective tissue diseases (p = 0.0286). Antikinectin was found exclusively among complete form of BD (p < 0.001), but there was no correlation with specific clinical manifestations.

We confirmed the previous observation that antikinectin is related to BD, especially in the complete form of disease. The specificity and predictive values are moderate.