Immunohistochemical detection of platelet microthrombi lesions, macrophagic infiltration, and activated complement deposition in kidney biopsies. CD61 (left), CD68 (middle), and C4d (right) antigens were detected with immunoperoxidase (brown) in serial sections of healthy kidney (a through c) and SLE nephritis tissues (d through l). SLE glomerular (d through f) or extraglomerular (g through i) markers are shown. Positive CD61 microthrombi (j), CD68 infiltration (k), and C4d perivascular deposition (l) were detected. Sections were counterstained with hematoxylin. Original magnification, ×400.