C3 and primary membranoproliferative glomerulonephritis: In MCD there is no IF staining or low level of mesangial staining of IgM or C3.6 In FSGS, there is IgM, C3 granular pattern on IF staining.10 In MN, there is usually positive staining of IgG and C3 in granular patterns.11 In MPGN, IF was positive for C3, IgG and IgM.12