Anti-Complement Autoantibodies in Membranoproliferative Glomerulonephritis and Dense Deposit Disease

Abstract

The complement system is an essential part of innate immunity by its role in protection against infections, but it is also involved in waste disposal and in modulating the adaptive immune response. Under physiological conditions complement activation is effectively regulated to restrain it to the required targets and extent, and to prevent collateral host tissue damage. An imbalance between complement activation and inhibition can lead to various diseases. Inappropriate regulation of complement activation, in particular that of the alternative pathway, is linked to kidney diseases. Mutations in complement components and regulatory molecules, and/or autoantibodies against complement proteins have been identified in patients with lupus nephritis, membranoproliferative glomerulonephritis (MPGN), dense deposit disease, C3 glomerulonephritis, CFHR5 nephropathy, and hemolytic uremic syndrome. This chapter summarizes the current knowledge on the role of complement dysregulation and of anti-complement autoantibodies in particular in dense deposit disease and MPGN.