Mechanism of renal damage in systemic autoimmune disorders

Renal involvement is one of the most serious manifestations of systemic autoimmune disorders such as systemic lupus erythematosus (SLE) and mixed cryoglobulinemia (MC). The antigen target of the nephritogenic humoral immune response can be classified as renal specific antigens; circulating antigens that can be trapped in the kidney (for example because of charge); soluble antigens that are bound by circulating antibodies. Antibodies that bind renal specific antigens or circulating antigens trapped in the kidney form in situ immunocomplexes. Antibodies that bind soluble antigens present in the vascular compartment form circulating immunocomplexes that can deposit in glomeruli, in basal membrane or mesangium, as well as in vessel walls, tubular basal membrane and interstitium. Deposition of circulating immune complexes has been suggested to play a major role in inducing renal damage in systemic autoimmune disorders. However, a number of studies indicate that autoantibodies present in SLE sera can bind antigens of glomerular cells or constituents of basal membranes. The aim of the present study was to analyze the specificity of antibodies reactive with renal antigens in SLE and MC. MATERIALS AND METHODS