Background Rheumatoid arthritis (RA) is the most common chronic inflammatory rheumatism. It's a complex autoimmune disorder. The aim of this study is to focus on the relationship between HLA-DRB1 genes and RA specific antibodies against cyclic citrullinated peptides (anti-CCP antibodies).

Methods This prospective study was performed on a total of 81 Tunisian patients with rheumatoid arthritis. All patients fulfilled the American College of Rheumatology (ACR 1987) criteria for RA. For each patient we assessed DNA and serum samples. The DNA was extracted from lymphocytes using a commercial kit (Quiagen). The HLA class II (DQB1 and DRB1) was performed by Polymerase Chain Reaction technique Specifying-sequence primers (PCR-SSP). The specific products of PCR were analyzed by 2.5% agarose gel electrophoresis. All tests include positive and negative controls appropriate for each blood sample. The phenotypes of patients were obtained through the Software One Lambda DNA/SOFTWARE (SSP2L-generic DRB/DQB).

Results The mean age of our population was 49.17±11.21 years (age 24–78). The disease average duration was 7.44±2.12 years (4 months - 29 years), 82.71% of RA were women and 17.29% were men. Seropositive RA were 80.24%, and 71% of RA have anti CCP positive antibody. Univariate analysis of the presence of anti-CCP antibodies in conjunction with HLA DRB1 and DQB1 was performed. Carriership of HLA DR*0301, 0401 and 1501 were significantly associated with the presence of anti-CCP antibodies (p<0.0001). Four DRB1 0401 carriers were homozygotes with three out of them having anti-CCP antibodies.

Carriership of HLA DQB1*0201, 0301, 0302,0501 and 0601 was associated with the presence of anti-CCP antibodies and so was HLA-DQB1*0401, but with a less significant association.

Conclusions Although no formal conclusions on causality can be drawn from this association study, these findings suggest that anti-CCP antibodies are associated with different phenotypes; which suggest that various pathogenetic mechanisms underlie the positivity for anti-CCP in RA.

Disclosure of Interest None declared