title: Flow cytometric human leukocyte antigen-B27 typing with stored samples for batch testing.
abstract: BACKGROUND
  Flow cytometry (FC) HLA-B27 typing is still used extensively for the diagnosis of spondyloarthropathies. If patient blood samples are stored for a prolonged duration, this testing can be performed in a batch manner, and in-house cellular controls could easily be procured. In this study, we investigated various methods of storing patient blood samples.
  
  
  METHODS
  WE COMPARED FOUR STORAGE METHODS: three methods of analyzing lymphocytes (whole blood stored at room temperature, frozen mononuclear cells, and frozen white blood cells [WBCs] after lysing red blood cells [RBCs]), and one method using frozen platelets (FPLT). We used three ratios associated with mean fluorescence intensities (MFI) for HLAB27 assignment: the B27 MFI ratio (sample/control) for HLA-B27 fluorescein-5-isothiocyanate (FITC); the B7 MFI ratio for HLA-B7 phycoerythrin (PE); and the ratio of these two ratios, B7/B27 ratio.
  
  
  RESULTS
  Comparing the B27 MFI ratios of each storage method for the HLA-B27+ samples and the B7/B27 ratios for the HLA-B7+ samples revealed that FPLT was the best of the four methods. FPLT had a sensitivity of 100% and a specificity of 99.3% for HLA-B27 assignment in DNA-typed samples (N=164) when the two criteria, namely, B27 MFI ratio >4.0 and B7/B27 ratio <1.5, were used.
  
  
  CONCLUSIONS
  The FPLT method was found to offer a simple, economical, and accurate method of FC HLA-B27 typing by using stored patient samples. If stored samples are used, this method has the potential to replace the standard FC typing method when used in combination with a complementary DNA-based method.
authors.affiliation: Department of Clinical Pathology, Kyungpook National University School of Medicine, Daegu, Korea.
authors.forename: Bo Young
authors.initials: BY
authors.lastname: Seo
authors.forename: Dong Il
authors.initials: DI
authors.lastname: Won
mesh_terms: D001792:Blood Platelets / Q000378:metabolism; D004912:Erythrocytes / Q000378:metabolism; D005434:Flow Cytometry; D005615:Freezing; D015796:HLA-B27 Antigen / Q000097:blood*; D015793:HLA-B7 Antigen / Q000097:blood; D006650:Histocompatibility Testing; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D025242:Spondylarthropathies / Q000175:diagnosis; D013696:Temperature
chemical_list: D015796:HLA-B27 Antigen; D015793:HLA-B7 Antigen
keywords: Flow cytometry; Frozen platelets; HLA-B27 typing; Sample storage