IGHG3 and systemic lupus erythematosus: The IF staining results indicated that lupus IgG1-injected MRL-lpr/lpr mice exhibited significantly less deposition of C1q, C3, IgG, IgG1, and IgG3 within their glomeruli at 19 weeks of age compared with that of control IgG1-treated and non-treated groups (Figures 5A,B).