Autoantibodies in minimal change nephrotic syndrome.

The presence of low level antibody (AAb) activity and circulating immune complexes (CIC) were studied in 17 patients with minimal change nephrotic syndrome (MCNS). Study groups include 12 MCNS without mesangial deposits (Group I) and 5 MCNS with mesangial deposits (Group II). In Group I reactivity against normal tissue antigens was demonstrated (kidney tubular microsomal antigen - 8, smooth muscle - 5, gastric cell - 5). In Group II reactivity against kidney basement membrane was demonstrated in all five patients. CIC were detected in eight (Group I - 6, Group II - 2). Dissociation of the CIC showed that they all contained antibodies with a corresponding autoantibody activity which could be removed by prior incubation with their complexed antigen. The presence of these AAb's and their formation of CIC may indicate their role in initiating a primary immunological insult to the kidney.