Genetic and immunological differences between Japanese patients with diffuse scleroderma and limited scleroderma

Objective. To study the association between HLA-DR and scleroderma (SSc), subsets of SSc, and autoantibodies in SSc. Methods. HLA-DR antigens were determined in 45 Japanese patients with SSc. The association between HLA-DR and SSc, subsets of SSc, and autoantibodies was analyzed in 22 patients with SSc excluding mixed connective tissue disease (MCTD)/overlap syndrome (OL). Results. When the 20 patients with MCTD and 3 patients with OL were excluded from the original patient group, a significant increase of HLA-DR2 was observed (59 vs 29% of controls, p < 0.01). The frequency of DR2 increased to 69% in patients with diffuse SSc (p < 0.01). DR1, which was not found in diffuse SSc, was found in 2 of 9 patients with limited SSc. The frequency of DR2 was significantly higher in patients with antitopoisomerase I (10/12, 83%, p < 0.05). In contrast, DR1 was found only in 2 patients with anticentromere antibodies (ACA), and all 5 patients with ACA had no HLA-DR2 (p < 0.01). Conclusion. Our results suggest that different HLA-DR markers may be associated with the production of distinct autoantibodies in diffuse SSc and limited SSc.