Scand J Rheumatol. 2003;32(6):337-42
Nissinen R, Paimela L, Julkunen H, Tienari PJ, Leirisalo-Repo M, Palosuo
T, Vaarala O.
National Public Health Institute, Department of Molecular Medicine,
Biomedicum, Helsinki, Finland.
OBJECTIVE:
Antibodies to citrulline-containing epitopes of filaggrin are highly specific for rheumatoid arthritis (RA).
We studied whether the enzyme peptidylarginine deiminase (PAD), responsible for the post-translational modification of peptide-bound arginine residues to citrulline, constitutes an antigen for patients with RA.
METHODS:
IgG antibodies to PAD were measured by enzyme-linked immunosorbent assay (ELISA) in sera from patients with RA, systemic lupus erythematosus (SLE), primary Sjogren syndrome (pSS), multiple sclerosis (MS) and healthy controls.
RESULTS:
Compared to healthy controls, raised levels of IgG antibodies to PAD were found in 50 of 57 recent-onset RA patients (88%) and in 40 (70%) of the same 57 patients 3 years later (p<0.0001 for both comparisons).
Eleven of 51 (22%) patients with RA of long duration, 19/43 (44%) patients with SLE and 16/19 (84%) patients with pSS, but none of 20 patients with MS, had elevated anti-PAD levels.
CONCLUSION:
The arginine-citrulline converting enzyme PAD was recognized as a new antigen against which patients with inflammatory rheumatic diseases frequently show IgG class antibodies.