C3 and proliferative glomerulonephritis: On the basis of immunofluorescence findings, proliferative glomerulonephritis can be classified as (1) immune complex or immunoglobulin (Ig)-mediated proliferative glomerulonephritis with or without C3 deposition, such as IgAN/post-infection glomerulonephritis with predominant IgA deposition and monoclonal immunoglobulin-associated proliferative glomerulonephritis; (2) pauci-immune proliferative glomerulonephritis; and (3) complement-mediated proliferative glomerulonephritis without or with only minimal  deposition of immunoglobulins [6].