Additive Effect of Tumor Necrosis Factor-α and Endotoxin on Bilirubin Cytotoxicity

Abstract

Clinical observation suggest that sepsis may enhance the risk of kernicterus. This study investigated the combined effects of bilirubin, endotoxin, and tumor necrosis factor-α (TNF-α), which simulate sepsis in a jaundiced mouse fibroblast cell line. The horseradish peroxidase oxidation method was applied for bilirubin-albumin titration studies to test the effect of endotoxin and TNF-α on bilirubin-albumin binding. A modified 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide method was used to study cytotoxicity. Bilirubin caused cytotoxicity in a dose-dependent manner in the cultured mouse fibroblasts. Such an effect was significantly amplified by TNF-α and endotoxin. TNF-α and endotoxin had no effect on the bilirubin-albumin titration curves. Our results have shown that TNF-α and endotoxin increase the cytotoxicity of bilirubin. These findings provide supportive evidence that sepsis would increase the risk of tissue damage by bilirubin. © International Pediatrics Research Foundation, Inc. 1999. All Rights Reserved.