Antinuclear matrix antibody. Hidden antinuclear antibody in patients with connective tissue diseases

A total of 435 serum samples from patients with different rheumatic diseases were screened for the presence of autoantibody to nuclear matrix components by indirect immunofluorescence on 0.1 mol/L HCl extracted HEp-2 cell and WiL2 cell substrates. A total of 28 specimens were positive in this assay. Eighteen of them were from patients with systemic lupus erythematosus (18 of 250), 2 from patients with rheumatoid arthritis (2 of 115), and 8 from patients with mixed connective tissue disease (8 of 10). Antigenic material for this antibody is resistant to DNase, partially sensitive to RNase, and sensitive to trypsin. This indicates that the antigen is composed of protein and possibly RNA. In immunoblot analysis, sera positive for this antibody in indirect immunofluorescence assay recognized different peptides. This suggests that protein peptides are the major antigenic material.