Cetirizine exerts anti-inflammatory effects on human neutrophils

Leukotrienes are potent lipid mediators involved in acute and chronic inflammatory processes and allergic inflammation. Cetirizine is an H1-receptor antagonist used in the treatment of allergic symptoms. We analyzed the effect of cetirizine on the formation of leukotriene B4 (LTB4) after stimulation of human peripheral blood neutrophils. The inflammatory mediators were analyzed after cellular activation with different stimuli: the Ca ionophore A23187, which bypasses membranous signal transduction elements; the bacterial peptide formyl-methionine-leucyl-phenylalanine (fMLP), which activates cells by binding to a GTP-protein (G-protein)-coupled receptor, and with sodium fluoride (NaF), which directly activates G-proteins. After cellular preincubation with cetirizine, the amounts of LTB4 generated from neutrophil granulocytes decreased significantly when the cells were subsequently stimulated with either fMLP or NaF, in contrast to stimulations with the Ca ionophore. The data provide evidence that cetirizine exerts anti-inflammatory effects apart from H1 antagonism.