Application Of HLA-B27 Antigen And Gene Detection In The Diagnosis Of Ankylosing Spondylitis

Objective To study the the expression of antigen and distribution of gene subtype of human leukocyte antigen B27(HLA-B27) in ankylosing spondylitis(AS), to analyze their association with AS and to discuss the clinical significance of the HLA-B27 antigen and gene for the early diagnosis of AS.Methods Between July 2013 and June 2014, 103 cases with AS were enrolled from three hospitals in South Fujian, while 105 controls without rheumatism,rheumatoid and mandatory spondylitis were randomly selected. Then the antigen and gene of HLA-B27 were detected by flow cytometry(FCM) and polymerase chain reaction –sequence based typing(PCR-SBT) in all the research objects. We analyze the antigen expression and the subtype distribution of HLA-B27 in AS patients, calculate the sensitivity and specificity of the two methods, and evalate the clinical diagnosis value of HLA-B27 antigen and gene for AS.Results1. Among the total 208 research objects, 103 were comfirmed AS patients, and 105 controls. A significant difference of the positive percentage of HLA-B27 antigen was found between the case and the control group(97.14% vs. 2.86%, P<0.001).Cases were more likely to be male(70.87% vs.47.62%,P=0.001)and younger(34.4vs.39.5, P=0.005), than that of the controls.2. The most common gene detected from the patients with AS were HLA-B27,accounting for 97.08%(99/103), followed by B40, B46 and B15, with detection rates of 29.13%, 17.48% and 17.48% respectively. We found 4 subtypes of HLA-B27( B2704, B2705, B2706 and B2715)in the AS group. Among these 4alleles, B2704 was the most widespread subtype, accounting for 93.93%(93/100).3. The sensitivety and specificity of HLA-B27 detected by FCM for AS were97.09% and 92.38%, and those were respectively 96.12% and 97.14% by PCR-SBT.4. The subtypes in the 5 cases with positive antigen and negative gene that comfirmed without AS were either B55 or B56.Conclusions 1. Patients with AS in South Fujian occurred mostly in young men, and the most common gene detected from the patients with AS were HLA-B27, followed by B40, B46, and B15. Four subtypes of HLA-B27( B2704,B2705,B2706,B2715)were found in the AS patients,in which the B2704 was the most widespread subtype.2. Both antigen and gene dection of HLA-B27 had a very good value in the AS diagnosis.The specificity of PCR-SBT was higher than that of FCM, though the sensitivety was slightly lower.3. Further detection of HLA-B55/B56 would enhance the specificity of HLA-B27 for AS diagnosis while detected by FCM..