Therefore, the goal of the proposed studies was to define more precisely the role of antibodies of the IgG3 subclass in MRL/lpr renal disease by directly comparing IgG3-producing (γ3 +/- and +/+) to IgG3-deficient (γ3 -/-) mice of the MRL/lpr background. The gene discussed is IGHG3; the disease is kidney disorder.