Objective: To determine quantitative expression of HLA-B27 in patients with ankylosing spondylitis (AS) and the relationship to clinical disease activity.
Methods: Quantitative reverse transcription-polymerase chain reaction (RT-PCR) was performed using specific primers to amplify the post-splicing mRNA of HLA-B27 gene in patients with AS (N = 15), B27+ healthy controls (N = 20), and B27+ unaffected family members (N = 30). Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) scores and expression of B27 mRNA were determined simultaneously. Serial measurements of B27 mRNA in one AS patient within a 9-month period were analyzed to determine the relationship between BASDAI scores and clinical therapy. For further validation of the significance of increased HLA-B27 mRNA expression in AS patients, extended experiments were conducted in another 10 patients with definite AS possessing HLA-B27/B60 (B*40012). Quantitative expression of HLA-B27 and B60 mRNA were determined simultaneously by RT-PCR.
Results: Expressions of HLA-B27 mRNA in HLA-B27+ AS patients were significantly higher compared to unaffected B27+ family members and B27+ controls. mRNA for HLA-B27 was observed to be present in higher amounts than for other HLA class I alleles. It was also noted that the BASDAI data were correlated with HLA-B27 mRNA estimated as 2DeltaDeltaCT in patients with definite AS. From a longitudinal case analysis, data on quantitative measurement of HLA-B27 mRNA was shown to be valuable for patient's management.
Conclusion: The expression of mRNA of HLA-B27 determined with quantitative RT-PCR correlated with clinical disease activity in patients with AS.