have shown that blocking macrophages in the kidney leads to decreased glomerulonephritis [16]. We stained kidney sections with the macrophage marker Mac2 and we observed decreased macrophage staining in the glomerular region of the kidney of CRIg-Fc compared to control-treated mice (Fig. 3G); quantification revealed this difference to be very significant (p b 0.0001) (Fig. 3H). These data together strongly suggest blocking the alternative complement pathway significantly arrests the onset of SLE pathology in the kidney as observed by reduced clinical scores and inflammation.