IL-1 RECEPTOR ANTAGONIST (IL-1RA) GENE POLYMORPHISM IN SJOGRENS-SYNDROME AND RHEUMATOID-ARTHRITIS

The gene encoding interleukin-l receptor antagonist (IL-lra) has a var iable allelic polymorphism. The IL1RN2 allele was recently described as a factor of severity in several autoimmune diseases and was paradox ically associated with increased production of IL-1ra by monocytes in vitro. We studied this polymorphism in 36 patients with possible or de finite primary Sjogren's syndrome and found that IL1RN2 was significa ntly more frequent in the definite than in the possible form, In rheum atoid arthritis, the frequency of the allele was not different from th at of controls. The serum levels of IL-lra were markedly higher in Sjo gren patients than in those of healthy subjects. By contrast, the sali vary IL-lra levels were decreased. Patients with the allele generally had lower salivary levels and higher serum levels than patients withou t the allele. In the group of patients with the definite syndrome, CRP and TGF-beta 1, two in vitro stimulators of IL-lra production, were c orrelated with IL-lra serum levels. Our results suggest that IL1BN2 i s a marker of more severe forms of Sjogren's syndrome. Its effect on s alivary and serum IL-lra may be distinct, suggesting separate regulato ry mechanisms. (C) 1998 Academic Press.