Studies were conducted to determine whether certain types of Ro autoantibodies are unique to subacute cutaneous lupus erythematosus and annular erythema of Sjögren's syndrome. Ten American subacute cutaneous lupus erythematosus sera, 11 Japanese annular erythema of Sjögren's syndrome sera, and 39 control sera were tested by enzyme-linked immunosorbent assay with recombinant 52- and 60-kd Ro fusion proteins, native 60-kd Ro protein, and native La/SS-B protein.
Japanese annular erythema of Sjögren's syndrome sera and American subacute cutaneous lupus erythematosus sera share several types of anti-52-kd and anti-60-kd Ro autoantibodies. However, these antibodies were found significantly more often and in significantly higher titers in sera from patients with Sjögren's syndrome who did not manifest these skin diseases. Patients with high Ro autoantibody titers were likely to have overt exocrine gland dysfunction.
The failure to identify disease-specific Ro autoantibodies in subacute cutaneous lupus erythematosus and annular erythema of Sjögren's syndrome sera suggests that additional factors influence the development of these skin diseases. However, similarities in the Ro autoantibody responses and in the clinical features of subacute cutaneous lupus erythematosus and annular erythema of Sjögren's syndrome suggest that these two skin diseases might arise from a similar pathogenic process.