C3 and type III hypersensitivity disease: More detailed immunohistological and electron microscopic studies of renal pathology revealed distinct subgroups, namely those with a typical immune complex disease, with prominent deposits of immunoglobulin (Ig), MPGN, those without or only trace Ig but prominent deposits of C3 (now termed C3 glomerulopathy, C3G),27, 28 and a further subgroup of patients with electron dense deposits on glomerular and tubular basement membranes staining strongly for C3, the appropriately named dense deposit disease (DDD).29