Human recombinant tumor necrosis factor (rTNF) bound to ML-1 and HL-60 human myeloid leukemia cells in a bimodal manner. Saturable high- affinity binding was maximal at approximately 3 nmol/L rTNF, whereas saturable low-affinity binding reached its maximum at approximately 30 nmol/L. As analyzed by computer program, the observed data fit a two- receptor site model, with p less than .05. High-affinity binding concentrations of rTNF caused the differentiation of both cell lines, whereas low-affinity binding concentrations abolished this effect in a concentration-dependent manner. Thus, the type of biologic response elicited with rTNF in these cells is a function of the concentration at which the factor is applied. If generally applicable, this bimodal effect may require consideration when rTNF is to be used therapeutically.

This content is only available as a PDF.