THE INFLUENCE OF ANTIFIBRONECTIN ANTIBODIES ON INTERACTIONS INVOLVINGEXTRACELLULAR-MATRIX COMPONENTS AND CELLS - A POSSIBLE PATHOGENIC MECHANISM

Antibodies, directed to the 30-kD collagen binding domain (CBD) of fib ronectin (Fn), have been previously demonstrated in sera from patients with systemic lupus erythematosus (SLE), and we now investigate the p ossible pathogenic effects of these antibodies on collagen-Fn and cell -Fn interactions. The binding of type 1 collagen to Fn was demonstrate d by ELISA, and could be specifically inhibited by the preincubation o f solid-phase immobilized Fn with anti-Fn antibodies from SLE sera. By using indirect immunofluorescent staining, anti-Fn antibody containin g SLE sera but not normal human serum (NHS) reduced the deposition of newly synthesized collagen and Fn on living human skin fibroblasts. We also found that sera from SLE patients containing anti-Fn antibodies significantly reduced thyroid cell attachment to Fn immobilized on pla stic compared with NHS. These effects were shown to be due to the pres ence of anti-Fn antibodies in these sera, as SLE sera depleted of anti -Fn antibodies did not reduce the deposition of collagen or Fn on cult ured fibroblasts, nor did they inhibit cell attachment.