ENHANCED EXPRESSION OF PLATELET-ACTIVATING-FACTOR RECEPTOR ON HUMAN EOSINOPHILS BY INTERLEUKIN-3, INTERLEUKIN-5 AND GRANULOCYTE-MACROPHAGE COLONY-STIMULATING FACTOR

The effects of interleukin-3 (IL/3), IL-5 and granulocyte-macrophage c olony-stimulating factor (GM-CSF) on the surface expression of platele t-activating factor (PAF) receptor on eosinophils was examined using a PAF receptor binding assay. Specific binding of [H-3]WEB 2086, a spec ific ligand for PAF receptor, to peripheral blood eosinophils obtained from healthy individuals was significantly increased when the cells w ere cultured with IL-3, IL-5, or GM-CSF for 12 h, compared with untrea ted cells. The PAF-induced increase in intracellular calcium ion conce ntration in eosinophils was markedly augmented by exposure to IL-5 for 12 h. These results suggest that these cytokines modulate the respons iveness of eosinophils to PAF through enhancement of PAF receptor expr ession on the cell surface.