Abstract
We examined the kinetics of polyamine uptake by human myeloid cells at different stages of maturity. The K m values of putrescine, spermidine and spermine transport by HL-60 cells were 52, 7.9 and 8.1 μM, respectively. These values decreased to 5.1, 1.7 and 0.77 μM, respectively, in HL-60 cells induced to mature past the promyelocyte stage by DMSO. In human PMNs, the respective K m values were 501, 479 and 381 μM. Transport by HL-60 cells was enhanced when intracellular polyamine levels were reduced with difluoromethylornithine. Thus, HL-60 cell maturation is accompanied by an increase in the affinity of their polyamine transport system. This system is much more efficient than that found in end-stage PMNs, suggesting that it plays a more important role in supporting the metabolic requirements of HL-60 cells. Alternatively, the low affinity of the PMN polyamine transport system could represent an adaptation to the high polyamine concentrations found at infection sites.
Published Version
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