IGHG3 and lupus nephritis: In lupus nephritis, autoantibodies detected in serum and in glomeruli, including antibodies versus implanted DNA/histones 2A, 3, and 4, are almost uniquely of the IgG2 isotype, with the exception of a few scattered IgG3 anti-DNA and IgG4 for anti-C1q in sub-epithelia membranous deposits of class V lupus nephritits [40].