Epibodies in autoimmunity: Antisera against autoantibodies to the renal glomerular basement membrane react with idiotypes as well as with autoantigens

Abstract

The results reported here show that we have experimentally produced xenogeneic anti-idiotypic antibodies to rat autoantibodies specific for the renal GBM and one of its components, laminin. Cross-reactive idiotypes have been detected by anti-idiotypic antibodies (anti-Id) on autoantibodies to the GBM (anti-GBM) from rats of different strains, confirming the results obtained in other autoantibody systems. During the course of studies aimed at determining whether anti-Id were directed to the paratope of anti-GBM antibodies, we have observed the presence of anti-GBM (and anti-laminin) antibodies in rabbit sera with anti-Id. Affinity chromatography experiments suggest that anti-GBM reactions detected with our anti-Id sera may be caused by a heterogeneous combination of anti-Id. Thus, Ab2α (and/or Ab2γ, all reacting with Ab1), Ab2α (epibodies, that bind to both Ab1 and GBM) and Ab3 (similar to Abl and therefore, reacting with GBM) may be present in our anti-Id sera. It has been suggested that antibodies displaying epibody properties may be involved in the mutual regulation of autoreactive clones and represent an important component of the autoimmune process

Key Words:

• Epibodies
• autoimmunity
• autoantibodies to renal GBM
• autoantibodies to laminin
• idiotype-anti-idiotype network