Evidence suggests that patients with in vivo speckled antinuclear antibody (ANA) patterns have high titers of circulating ANA, specifically anti-U1 RNP antibody. A small percentage of patients with high titers of anti-U1 RNP antibody have anti-nuclear matrix antibodies, and some also demonstrate in vivo ANA. This study was designed to screen for the presence of anti-nuclear matrix antibodies in patients with in vivo ANA.
Anti-nuclear matrix antibodies were detected by indirect immunofluorescence on HCI-extracted HEp-2 cell substrate, by enzyme-linked immunosorbent assay, and by immunoblot analysis.
All 10 patients with in vivo ANA were found to have anti-nuclear matrix antibody demonstrated using HCI-extracted HEp-2 cell substrate, and all exhibited antibody activity to a 36-kd protein from nuclear matrix antigen.
These results suggest that anti-nuclear matrix antibodies are a major factor in the development of in vivo ANA.