Splenocyte depletion observed in chronic ethanol-treated rats (ETRs) was studied in relation to apoptosis. The rats were fed with ethanol in a Liber-DeCarli liquid diet (36% of total calories as ethanol) for 7 weeks. Spleens of ETRs and control rats were examined by the terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) method, immunohistochemistry using anti-rat p53 and RM4 (specific for macrophages) monoclonal antibodies, and transmission electron microscopy (TEM). The splenic white pulp in ETRs decreased in size and showed a moth-eaten appearance because of the severe depletion of splenocytes. Most TUNEL-positive cells aggregated into clusters or nests and were not isolated in the white pulp of ETRs. The site of RM4 immunoreactivity was consistent with that of clusters of TUNEL-positive cells. The p53 immunoreactivity was observed in apoptotic splenocytes that were isolated or phagocytosed by macrophages. TEM study revealed the increase in tingible body macrophages phagocytosing apoptotic splenocytes in their cytoplasm in ETRs. Chronic ethanol intake certainly induces apoptosis in splenic white pulps, and tingible body macrophages act as both sentinels and scavengers of apoptotic splenocytes expressing p53.
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