PAF-acether transfer activity in HL-60 cells is induced during differentiation

Platelet-activating factor is a proinflammatory lipid active at subnanomolar concentrations. The intermembrane transfer of a biologically active PAF analog has been previously demonstrated in macrophages. Here we demonstrate that the specific activity of this transfer activity increases when HL-60 cells are induced to differentiate by treatment with dimethyl sulfoxide, dibutyryl cAMP or phorbol diester. In undifferentiated HL-60 cells, methylcarbamyl-PAF transfer activity was only 0.56 U.min-1.mg-1. This basal value was increased 2.6 and 6.7 times upon granulocytic and macrophagic differentiation, respectively. On the other hand, the transfer of 2-O-methyl-PAF, a cytotoxic analog with no PAF biological activity, remained very low and did not vary during differentiation.