Comparison of the Flowcytometric HLA-B27 Determination Methods

Yoon, Soo Young; Lee, Chang Kyu; Cho, Yoon Jeong; Ma, Kyung Ran; Kim, Young Kee; Lee, Kap No

Abstract

BACKGROUND: The flowcytometric analysis of HLA-B27 gives more objective results and is performed more rapidly than traditional serologic methods. We have used a flowcytometric method using only anti-HLA-B27 monoclonal antibody, but it gave frequently borderline mean fluorescence intensity (MFI) results. The authors compared the method using anti-HLA-B27 antibody (HLA- ABC-m3, Serotec) with the Becton Dickinson (BD) method which uses different HLA-B27 antibody (GS145.2) with CD3 antibody.
METHODS
The 59 patients that requested HLA-B27 testing were measured by two methods. In the former method, the mononuclear cells were stained with HLA-B27-FITC and the MFIs were determined in lymphocytes. In the BD method, the whole blood was directly stained with CD3-PE and HLA-B27-FITC. The MFIs were determined in the CD3+ cells, and compared with the MFI of the standard. For the cases showing discrepancy in the two methods or borderline values, the HLA-ABC typing was done.
RESULTS
Of 21 showing discrepancy, 10 samples had undergone HLA typing. Among nine samples that were positive by the Serotec method but negative by the BD method, four samples were B7, one B40, one B54 and three B7 CREG negative. One that was negative by the Serotec method but positive by the BD method was confirmed as HLA-B27.
CONCLUSIONS
The Serotec method showed significant overlap between the MFIs of HLA-B27 and non B27 samples that resulted in a relatively low efficiency compared with the BD method. The discrepant results of the two methods seem to be due to maily the specificity of the antibody used.