{"type":"root","children":[{"type":"paragraph","children":[{"type":"text","value":"Complement component 3, often simply called C3, is a protein of the immune system. It plays a central role in the complement system and contributes to innate immunity."}]},{"type":"paragraph","children":[{"type":"text","value":"C3 glomerulopathy was recently coined to describe renal biopsy appearances characterized by the presence of glomerular deposits composed predominantly of C3 in the absence of significant amounts of Ig. The presence of C3 in the absence of Ig suggests activation of complement by antibody-independent pathways, typically the alternative pathway, and many patients with this type of renal lesion have evidence of genetic or acquired alternative pathway dysregulation. C3 glomerulopathy has been further divided into dense deposit disease (DDD) and C3 glomerulonephritis (C3GN) based on electron microscopy (EM) appearances. The underlying genetic defect has been identified in some hereditary forms of C3GN such as CFHR5 nephropathy. Lupus nephritis is an inflammation of the kidneys caused by Systemic Lupus Erythematosus. Immunofluorescence reveals positively for IgG, IgA, IgM, C3, and C1q."}]}]}