Human PAF receptor gene expression: induction during HL-60 cell differentiation.

Platelet-activating factor is a potent lipid mediator of inflammation and immune regulation. Its numerous biological activities are mediated through specific receptors on the plasma membranes of responsive cells. The expression of such receptors may be modulated by various agents, including those responsible for cell differentiation. Here, we demonstrate that differentiation of the human promyelocytic leukemia cell line HL-60 by 1 alpha,25(OH)2 vitamin D3 towards the macrophage phenotype is associated with induction of PAF receptor gene expression: PAF receptor mRNA accumulation correlates with the induction and development of specific PAF responsiveness as assayed by [Ca2+]i fluxes. Our studies suggest that PAF responsiveness parallels macrophage differentiation and that PAF receptor expression can be regulated at the transcriptional level.