Proteinuria was determined with Albustix strips (Bayer) using a 0–4 scale. Transverse sections of kidney were processed and stained with hemotoxylin and eosin (H&E) and periodic acid Schiff (PAS). Renal lesions were classified as previously described based on a modified International Society of Nephrology/Renal Pathology Societyclassification (15 (link)). Briefly glomerular lesions were classified: negative, mesangial matrix (PAS+) expansion (Mm), mesangial expansion with increased mesangial cellularity (Mc), capillary hyaline (immune complex type) deposits (HD) and proliferative glomerulonephritis (glomerular hypercellularity with capillary loop involvement, which was global [Pg] or segmental [Ps]). Extent of involvement was graded on a 1–4 scale. Glomerular sclerosis was graded separately. Chronic (mononuclear cell) inflammation was classified as perivascular or interstitial (ICI) and graded as for glomerular inflammation. Glomerular macrophages and CD4+ T cells weredetected on re-hydrated 8 µM sections first incubated with 0.6% H2O2 and 0.2% NaN3 to inhibit endogenous peroxidase activity and stained with biotin-conjugated anti-CD68 (Serotec) or anti-CD4 (BD Pharmingen). HRP-streptavidin (Vector) and DAB substrate were added and positive cells developed a brown color. Sections were counterstained with Mayer's hematoxylin solution (Sigma). The numbers of CD68+ or CD4+ cells were averaged from 10 randomly selected glomeruli under high power field for each kidney section. Detection of glomerular immune complex deposits were assessed on frozen sections stained with anti-IgG2a or anti-C3 FITC as previously described(15 (link)).Formalin-fixed inter-scapular skin sections were stained with H&E.