Comparison of different methods for the detection of autoantibodies in autoimmune diseases.

Different immunological techniques were compared for their sensitivity in detecting some important autoantibodies in the sera of patients with rheumatic diseases. Sera of patients with systemic lupus erythematosus were screened for anti-dsDNA, Sm, and RNP autoantibodies by Crithidia luciliae assay, Farr assay, enzyme immunoassay, and immunoblotting. Sera of patients with Sjögren's syndrome were screened for anti-SSA and anti-SSB antibodies by enzyme immunoassay, counter immunoelectrophoresis, and immunoblotting and sera of patients with scleroderma for SCL-70 autoantibodies by enzyme immunoassay counter immunoelectrophoresis, and immunofluorescence on Hep-2 cells. Enzyme immunoassay and counter immunoelectrophoresis gave the most positive results and the best agreement compared with the other techniques. Immunofluorescence gave few positive results for each antibody evaluated. Immunoblotting gave intermediate results for all autoantibodies except anti-SSA, where the prevalence was low. There was no relationship between levels of dsDNA, Sm, and RNP antibodies and disease activity score in systemic lupus erythematosus patients.