Objective: To identify new IgG autoantibodies in rheumatoid arthritis patients’ sera.
Methods: We tested serum samples from 19 rheumatoid arthritis patients with given HLA-DR genotypes, from 7 spondylarthropathy patients, 2 lupus patients, 4 systemic sclerosis patients and 10 healthy individuals on 8268 human protein arrays.
Results: We identified four antigens (PAD4, PKC beta 1, PIP4K2C and BRAF) that were recognized almost uniquely by sera from patients with RA on protein arrays. Using purified proteins, we confirmed that PAD4 and BRAF are recognized almost uniquely by RA patients.
Conclusion: We identified PAD4 and BRAF as RA specific autoantigens.