To clarify the clinical significance of the antibody against v-raf murine sarcoma viral oncogene homologue B1 (BRAF) in the diagnostic  practice of rheumatoid arthritis (RA).
In the study, 112 patients with RA, 112 patients with other rheumatic diseases,and 73 healthy individuals  were recruited . With recombinant human BRAF protein as antigen, we examined the level of anti-BRAF antibody in all the patients by enzyme-linked  immunosorbent assay(ELISA), The clinical data of the RA patients were collected simultaneously, and analysed statistically by using SPSS 13.0.
The positive rate of anti-BRAF antibody was 53.6% in the RA patients, which was significantly higher than that of the normal control group (4.1%,P<0.01)and other rheumatic diseases groups (P all<0.01)except osteoarthritis group. The titer of anti-BRAF antibody was also notably  higher in the patients with RA than in other rheumatic diseases and normal control groups(P all <0.01).The diagnostic sensitivity and specificity of anti-BRAF antibody for RA were 53.6% and 84.3% respectively. The positive rate of anti-BRAF antibody in rheumatoid factor, anti-cyclic citrullinated peptide  antibody, antikeratin antibody,antiperinuclear factor negative groups were 52.6%,38.2%, 30.3% and 31.0%respectively. It showed significant negative  correlation between the titer of anti-BRAF antibody and patient's age, disease duration and the level of CRP.
The anti-BRAF antibody  contributes to the diagnosis of RA, and may act as a supplement of other autoantibodies.