Diagnosis of systemic lupus erythematosus. Importance of antinuclear antibody titers and peripheral staining patterns.

Titers and patterns of antinuclear antibodies (ANA) in sera from 134 normal blood donors, 20 patients with rheumatoid arthritis, 15 patients with systemic scleroderma, and 32 patients with diagnosed or suspected systemic lupus erythematosus (SLE) were studied. The difference between the findings with sera of patients with SLE and normal subjects in terms of high (greater than 160) titers of ANA was greater than in terms of peripheral staining patterns. However, in comparing sera from patients with SLE with sera from patients with other connective tissue diseases, greater differences were found in the incidence of peripheral patterns of ANA compared to differences in the frequency of high ANA titers. Maximum specificity in the diagnosis of SLE was achieved when both titers and patterns of ANA were considered.