The Clinical Significance of Shared Epitope in Rheumatoid Arthritis

Minn, Doh Sik; Kim, Think You

Abstract

OBJECTIVE
The application of DNA sequencing and molecular-based typing to detect HLA-DRB1 alleles showed that those associated with rheumatoid arthritis (RA)shared a consensus amino acid sequence (QKRAA or QRRAA)at positions 70-74 of the third hypervariable region of the HLA-DRB1 chain.This is defined as the so-called 'shared epitope'. Many studies reported that shared epitope was associated with RA susceptibility and disease severity.Also,DRB1*0401 and DRB1*0404 alleles confer genetic predisposition to RA in Caucasian.We studied the frequency of shared epitope,DRB1*04,DRB1*0401,and DRB1*0404 in Korean RA patients using monoclonal antibodies.We also tried to investigate the influence of these factors on susceptibility and severity in RA patients and to evaluate the method.
METHODS
RA patients were 32 persons with classical or definite RA who attended the Hospital for Rheumatic Diseases,Hanyang University Hospital,Seoul,Korea.We separated lymphocytes from whole blood and used indirect immunofluorescence staining method using four monoclonal antibodies (Terra Nova,Canada).
RESULTS
The frequency of DRB1*04 and shared epitope were 56%and 56%, respectively.That of DRB1*0401 and DRB1*0404 were positive in 19%and 9%of all patients,respectively.There were no association between share epitope and disease severity.
CONCLUSION
The shared epitope is expressed with high frequency,as many as DR4 frequency in Korean RA patients.But the frequency of DRB1*0401 and DRB1*0404 is low different from Caucasian.The used method is simple and easy to screen shared epitope.