Clinical significance of serum anti-microbial antibodies test in inflammatory bowel disease

Abstract

Objective To investigate the clinical significance of serum anti-Saccharomyces cerevisias antibody （ASCA）,anti-outer membrane porin C （anti-OmpC）,antibody to Pseudomonas fluorescens-associated sequence I2 （anti-I2 ）and antibody to bacterial flagellin （anti-CBirl ）in the diagnosis and treatment of inflammatory bowel disease （IBD）.Methods From 2011 to 2013,87 patients with IBD were enrolled and divided into Crohn′s disease （CD）group （66 cases）and ulcerative colitis （UC）group （21 cases）.A total of 62 age and gender matched healthy individuals were enrolled as the control group. Fasting blood samples （2 mL）of the subjects were collected.The expression of ASCA,anti-OmpC,anti-I2 and anti-Cbirl antibodies was detected with enzyme-linked immunosorbent assay （ELISA）kits.The diagnosis value of each antibody in IBD and the differential diagnostic value of in UC and CD were compared by receiver operating characteristic （ROC）curve.Results The area under the curve （AUC）of ASCA between IBD and the healthy control group,between CD group and UC group was 0.580 and 0.512, respectively;the accuracy in diagnosis was low.The AUC of anti-CBirl between IBD and the healthy control group was 0.617.There was no differential diagnosis significance of the other antibodies.The positive rate of ASCA in IBD group was 62.1 % （54/87）,which was significantly higher than that in the control group （38.7%,24/62）.The positive rates of anti-OmpC and anti-I2 in IBD group was significantly lower than those in the control group and the differences were statistically significant （both P 〈0.05）.No difference was observed in positive rates of serum antibodies among the others groups （all P 〉0.05）.The specificity,sensitivity,positive predictive value （PPV）and negative predictive value （NPV）of ASCA in differential diagnosis of CD and UC was 52.4%,66.7%,81 .48% and 33.33%,respectively.The specificity and sensitivity of anti-OmpC,anti-I2 and anti-CBirl in differential diagnosis of CD and UC was 81 .0% to 100.0% and 9.1 % to 37.9%,respectively.The specificity,sensitivity,PPV and NPV of double-positive ASCA and anti-I2 in the diagnosis of CD was 57.1 %,86.4%,82.6% and 50.0%, respectively.The positive rate of ASCA and anti-I2 in CD group was significantly higher than that in UC group （84.8%（56/66）vs 57.1 % （12/21 ）;χ2 =5 .633,P =0.018 ）.Conclusions Positive ASCA has some significance in the diagnosis of patients with IBD in our country.The detection of anti-I2 can help to diagnose ASCA negative CD.Because of low sensitivity and positive rate,anti-OmpC and anti-CBirl have limited value in the diagnosis of IBD and the differential diagnosis of UC and CD in our country. Key words: Inflammatory bowel diseases;  Diagnosis, differential;  Antibodies, fungal;  Antibodies, bacterial;  Anti-Saccharomyces cerevisiae antibodies~ Bacterial outer membrane pore protein C;  Pseudomonas fluorescens associated sequence I2