IL-4 production by human polymorphonuclear neutrophils

Polymorphonuclear neutrophils (PMN) are. phagocytic: cells, able to secrete a large range of cytokines, including inflammatory cytokines, chemokines, as well as the Th1 cytokines interferon-gamma (IFN-gamma) and interleukin ( IL)-12. Although PMN do not seem to express IL-10 and IL-13, no information exists on the ability of PMN to produce IL-4. Therefore intracellular flow cytometry was performed in the presence or absence of Brefeldin A, Similar ly to eosinophils, freshly isolated neutrophils from normal donors containe d low amounts of IL-4, which significantly increased upon culture with Bref eldin A (P < 0001), Immunostaining performed on cytospin preparations of no rmal granulocytes confirmed the presence of intracellular IL-4. Using a hig hly sensitive ELISA, the levels of IL-4 secreted by cultured PMN and periph eral blood mononuclear cells (PBMC) Tc ere compared, PBMC secrete up to 60 times more IL-4 as PMN but, in the presence of calcium ionophore, only PMN shore-ed a slight but significant increase in IL-4 secretion (P < 0.05), In conclusion, we report here the presence within human PMN of intracellular IL-4, which can at least partly be released under calcium ionophore stimula tion. The relevance of this production of IL-4 by human PMN is discussed.