Hexadecylphosphocholine induces interferon-gamma secretion and expression of GM-CSF mRNA in human mononuclear cells

The effects of hexadecylphosphocholine (HePC) on secretion of interferon-gamma (IFN-gamma) and steady-state levels of IFN-gamma and GM-CSF mRNA were studied in human mononuclear cells. Cells from healthy donors were stimulated with either interleukin 2 (IL-2) alone, IL-2 plus phytohemagglutinin (PHA), or IL-2 plus HePC. In IL-2-treated cultures, the concentration of IFN-gamma was low. IFN-gamma and GM-CSF transcripts were not detectable by Northern blot analysis. In contrast, IL-2 plus HePC strongly increased the expression of the IFN-gamma and the GM-CSF genes and the secretion of IFN-gamma in most analyzed cultures. A similar effect could be detected with IL-2 plus PHA. The HePC-mediated enhancement of cytokine expression appeared later than the PHA-induced stimulation. These data indicate that HePC is able to enhance the immune response of IL-2-stimulated mononuclear cells resulting in GM-CSF and IFN-gamma gene expression and IFN-gamma secretion.