Tumor necrosis factor-induced downregulation of its receptors in HeLa cells

Tumor necrosis factor (TNF) induced loss of TNF receptors in HeLa cells was studied using acid elution technique, which could distinguish surface occupancy and real loss of receptors. Exposure of HeLa cells to TNF resulted in a rapid reduction in the number of TNF receptors without affecting the apparent binding affinity. The binding of transferrin after treatment with unlabeled TNF was unaffected. The TNF-mediated decrease in receptor number on the cells was reversible. Following removal of TNF from growth medium, binding activity was restored within 3 h. Cycloheximide prevented the restoration of TNF receptors, suggesting that de novo synthesis of receptors was required to restore the binding activity.