Localization of metallothionein (MT) isoforms I + II in healthy kidneys and in lupus nephritis. Representative results of immunohistochemical analyses. (a) Healthy renal tissue. CytoplasmicMT-I+II staining is seen in proximal tubular cells. Concurrent MT-I+II staining is frequently observed in material radiating from the epithelial brush border into the tubular lumen. No staining is observed in glomeruli. (b) Inner medullary zone of healthy kidney. MT-I+II staining is seen in the epithelium of the collecting tubules but not in cross-sectioned thin segments of Henle's loop. (c) Renal tissue from patient with lupus nephritis and a tubular MT score of zero as defined in the text. Cytoplasmic MT-I+II staining is observed in proximal tubular cells. (d) Renal tissue from another patient with lupus nephritis. Intense luminal MT-I+II staining with concomitant epithelial cell MT-I+II depletion is observed in several cross-sectioned proximal tubules. Glomeruli are MT-I+II-negative. (e) Lupus nephritis. Same findings as in (d). (f) Lupus nephritis. Some proximal tubules display pronounced luminal MT-I+II staining in combination with MT-I+II depletion of the lining epithelial cells (black arrows). In other tubules, some epithelial cells display cytoplasmic MT-I+II staining (white arrows). (g) Lupus nephritis. Several cross-sectioned proximal tubules with predominantly luminal MT-I+II staining are shown. As in (f), some tubules display MT-I+II depletion of the epithelium (black arrows). In other tubules, cytoplasmic MT-I+II staining is seen in a proportion of the epithelial cells (white arrows). (h) Pauci-immune glomerulonephritis in Wegener's granulomatosis. Two tubules with a predominantly luminal MT-I+II expression pattern are marked (arrows).