Dark and Light Cells and Localizations of Aflatoxin B1 Demonstrated in Liver and Kidney Cells by Immuno-electron Microscopy

Ultrastructural appearance of dark and light cells and immunocytochemical localizations of aflatoxin B1 (AFB1) in rat and mouse liver and kidney cells are demonstrated. Dark and light cells were observed in the rat, mouse liver and kidney cells of normal, tumor-bearing mice and AFB1-treated livers with either perfusion-fixation or immersion-fixation, Male Sprague-Dawley rats (120-150 gm), male NIH mice (25-30 gm) were injected intraperitoneally with a single dose of AFB1 and then sacrificed after 30 minutes to 2 weeks. Monoclonal antibodies were obtained by using AFB1-BGG (bovine gamma globulin) conjugates as antigen, and screened by AFB1-BSA (bovine serum albumin). Tissue samples are fixed with perfusion-fixation methods, Immuno-peroxidase staining indicated that AFB1 in liver is mainly located in the microsomes and in the nucleolus. However, in the proximal convoluted tubule cells of kidney, AFB1 is primarily located in the mitochondria and in the cytoplasm. Negative AFB1 bindings were observed in the Golgi apparatus, endoplasmic reticulum and intercellular connective tissues. The cytotoxicity of AFB1 appeared at 2 hours and recovered after 2 weeks. Accumulation of AFB1 in the mitochondria or microsomes at early stages of AFB1-treatments may explain different mechanism of injuries occurred in liver and kidney cells.