Detection of autoantibodies to killer immunoglobulin-like receptors using recombinant fusion proteins for two killer immunoglobulin-like receptors in patients with systemic autoimmune diseases.

Abstract

To investigate the existence of autoantibodies to killer immunoglobulin-like receptors (KIRs), especially p58.1 (KIR2DL1) and p58.2 (KIR2DL3), in patients with systemic autoimmune diseases. Sera from 30 patients with systemic lupus erythematosus (SLE), 30 patients with rheumatoid arthritis (RA), 22 patients with Behçet's disease, and 20 healthy control subjects were tested for anti-p58.1 and anti-p58.2 antibodies by Western blot analysis using recombinant p58.1 and p58.2 proteins. Furthermore, clinical features and laboratory data were compared between the anti-p58.1/58.2 antibody-positive and -negative patients. Anti-p58.1 antibodies were detected in 7 (23.3%) of the 30 patients with SLE, 9 (30%) of the 30 patients with RA, and 6 (27.3%) of the 22 patients with Behçet's disease. Anti-p58.2 antibodies were detected in the same 22 patients who were positive for the anti-p58.1 antibodies. None of the serum samples from the healthy donors were positive for antibodies to the recombinant p58.1 or p58.2 molecules. Compared with the anti-p58.1/ 58.2 antibody-negative patients, the anti-p58.1/58.2 antibody-positive patients had significantly elevated levels of serum IgG in all 3 diseases tested, an accelerated erythrocyte sedimentation rate in RA and SLE, and decreased white blood cell counts in RA. This report is the first to describe the presence of autoantibodies to KIR2DL (p58.1 and p58.2) in the sera of patients with systemic autoimmune diseases. Considering the correlation with several clinical features, these autoantibodies may be involved in the pathologic process of the autoimmune diseases.