Contrasting effect of interleukin-4 on the expression of cytosolic phospholipase A(2), 5-lipoxygenase and 5-lipoxygenase-activating protein in peritoneal macrophages from control and ovalbumin-sensitized rats

Interleukin-4 (IL-4), which has been widely described as an anti-inflammato ry cytokine, can also exert proinflammatory effects. In this study, we exte nd these findings to demonstrate, in an allergic model, the dual effect of IL-4 on arachidonic acid (AA) metabolism in macrophages, In peritoneal macr ophages from control rats (cPM), IL-4 had no effect on cPLA, and 5-LO expre ssion, but increased FLAP expression without affecting basal and A23187- or PMA-challenged arachidonic acid (AA) metabolism, In contrast, in peritonea l macrophages from ovalbumin-sensitized rats (sPM), IL-4 decreased cPLA(2), 5-LO and FLAP expression and PMA-challenged eicosanoid production, A23187- challenged AA metabolism of sPM was not affected by IL-4 pretreatment. Thus, IL-4 acts differently on cPLA(2), 5-LO and FLAP expression and AA met abolism in peritoneal macrophages depending on their resident or sensitizat ion-induced differentiated status.