In this study, a difference of 2+ intensity was noted in antibodies of C3 in two cases of lupus nephritis and IgA in one case of IgA nephropathy. IgA nephropathy, which is characterized by dominant or co-dominant mesangial IgA immune deposits, with weak IgA may show false-negative staining for IgA on IF-FFPE [3,9]. This evidence concerns the gene C3 and lupus nephritis.