Laboratory criteria for a diagnosis of systemic lupus erythematosus.

Patients with systemic lupus erythematosus (SLE) and other connective tissue diseases were surveyed for the presence of antibodies to normal DNA, antibodies to a ribonuclease-insensitive acidic nuclear protein, and immune deposits in normal skin. While 80% of patients with SLE had abnormal values for at least two of these three tests, none of the patients with other connective tissue diseases had more than one abnormal value. The presence of RBC autoantibodies was found along with one of the other abnormal laboratory tests in 76% of patients with SLE, including 14% of patients not found to have two abnormal tests. None of the other patients tested had RBC autoantibodies. These findings suggest that a set of laboratory tests can be constructed as criteria for a diagnosis of SLE that would be as specific as the presently employed American Rheumatism Association criteria.