The HLA-DRB1 shared epitope is not associated with antibodies against cyclic citrullinated peptide in Chinese patients with rheumatoid arthritis

Objective: Rheumatoid arthritis (RA) is a destructive autoimmune polyarthritis that has been associated with a group of human leucocyte antigen (HLA)-DRB1 alleles that share a common amino-acid sequence at residues 70-74 called the shared epitope (SE). Recently, anti-cyclic citrullinated peptide (CCP) antibodies have also been reported to be associated with HLA-DR4 and have gained wide acceptance as early diagnostic markers for RA in Caucasian patients. The current study was performed to investigate whether the association between the SE (HLA-DRB1*0401 04 05 10) and anti-CCP antibodies is also present in Chinese Han patients with RA. Methods: One hundred and four RA patients and 122 healthy controls were recruited. HLA-DR4 was detected by the sequence-specific primer polymerase chain reaction (SSP-PCR) phototyping method. Anti-CCP antibodies and immunoglobulin M rheumatoid factor (IgM-RF) were measured by enzyme-linked immunosorbent assay (ELISA) and laser nephelometry, respectively. Results: Of the Chinese patients with RA, 76.5% exhibited anti-CCP antibodies compared with none of the controls (76.5% vs. 0%, p