THE AUTOANTIBODY RESPONSE TO RO SSA IN CUTANEOUS LUPUS-ERYTHEMATOSUS/

Background and Design: Seventeen patients with subacute cutaneous lupu s erythematosus (SCLE) were compared with 15 patients with discoid lup us erythematosus (DLE) to evaluate the relationship of 60- and 52-kd R o/SSA autoantibodies to the clinical diagnosis and to evaluate assays for anti-Ro/SSA. Results: All serum samples from patients with SCLE ha d precipitating anti-Ro/SSA antibodies in immunodiffusion, and all had high titer anti-60-kd Ro/SSA in enzyme-linked immunosorbent assay. Im munoblotting was inadequately sensitive for detecting anti-60-kd Ro/SS A. Fifteen patients with SCLE had anti-52-kd Ro/SSA (11 high titer, fo ur low titer). Only one of the 15 patients with DLE had precipitating, high-titer anti-Ro/SSA. Nine other patients with DLE had low-titer an ti-60-kd Ro/SSA, and four had low-titer anti-52-kd Ro/SSA. Low-titer a nti-Ro/SSA did not confer an increased risk for photosensitivity in th e DLE group. Conclusions: High-titer, precipitating antibodies to Ro/S SA are typical of SCLE and unusual in DLE. Low-titer, nonprecipitating antibodies to Ro/SSA are common in DLE and could be an indication of pathogenic factors shared with SCLE. However, low titers of antiRo/SSA do not confer a significant risk for SCLE skin lesions. For the purpo se of clinical evaluation of skin disease, immunodiffusion assays for anti-Ro/SSA are cost-effective and informative.