Vol. 281, Issue 2, 624-628, 1997

Losartan, a Selective Inhibitor of Subtype AT1 Receptors for Angiotensin II, Inhibits the Binding of N-Formylmethionyl-leucyl-phenylalanine to Neutrophil Receptors¹

Silvina Raiden , Mirta Giordano, Graciela Andonegui, Analía S. Trevani, Daniel H. López, Victor Nahmod and Jorge R. Geffner

Laboratorio de Inmunología, Instituto de Investigaciones Hematológicas, Academia Nacional de Medicina (S.R., M.G., G.A., A.S.T., D.H.L., J.R.G.), and Instituto de Investigaciones Médicas, Facultad de Medicina, Universidad de Buenos Aires (S.R., V.N.), Buenos Aires, Argentina

Losartan, a selective antagonist of AT1 receptors for angiotensin II, is widely used clinically to manage hypertension. We report here that losartan markedly inhibits neutrophil shape change, adherence and chemiluminescence responses triggered by N-formylmethionyl-leucyl-phenylalanine (fMLP), without affecting responses induced by immune complexes, zymosan or concanavalin A. Neither saralasin, another antagonist of angiotensin II receptors, nor captopril, an angiotensin-converting enzyme inhibitor, reproduced the effects of losartan. It was also observed that neutrophil responses triggered by fMLP were not affected by exogenously added angiotensin II. The effect of losartan on the binding of fMLP was measured using [³H]fMLP. It was found that losartan inhibits the binding of [³H]fMLP to neutrophil receptors. As observed for neutrophils, studies performed with monocytes showed that losartan inhibits chemiluminescence emission triggered by fMLP, without affecting chemiluminescence responses triggered by immune complexes, zymosan or concanavalin A.