Keratinocyte growth stimulation by granulocyte-macrophage colony-stimulating factor (GM-CSF)

Human granulocyte-macrophage colony stimulating factor (GM-CSF) is a 22 kD glycoprotein derived from activated T cells, endothelial cells, fibroblasts and macrophages. It stimulates the proliferation and differentiation of haematopoietic cells and certain nonhaematopoietic cells. This study investigated the effect of GM-CSF on cultured human keratinocytes and determined whether these cells express GM-CSF receptors. Measurement of keratinocyte growth by image analysis showed that GM-CSF mildly stimulated the growth of keratinocytes. With 4 ng/ml GM-CSF the growth of primary keratinocytes and subcultured keratinocytes was only stimulated up to 25% and 18% of the control cell level, respectively. Human keratinocytes were incubated with GM-CSF at 4 ng/ml for 4 days to induce receptor expression. These cells showed only a weak positive reaction on affinity labelling using digoxigenated GM-CSF. We conclude that keratinocyte growth may be stimulated by GM-CSF but that the presence of GM-CSF receptors on these cells is equivocal.