Migration of human monocytes in response to procalcitonin

Objective: Circulating serum levels of procalcitonin rise significantly during bacterial infection. Because calcitonin is known to be a monocyte chemoattractant, we investigated whether procalcitonin, a prohormone of calcitonin, also affects leukocyte migration. Design: Prospective, controlled in vitro study. Setting: University research laboratories. Interventions: Forearm venous blood polymorphonuclear neutrophils and monocytes were isolated from healthy human donors. Cell migration was assessed in a blindwell chemotaxis chamber. The distance of migration into filter micropores was measured. To biochemically confirm functional data on cell migration, effects of procalcitonin on cellular levels of cyclic adenosine monophosphate were measured by high-performance liquid chromatography. Measurements and Main Results: Both procalcitonin and calcitonin elicited dose-dependent migration of monocytes at concentrations from the femtomolar to the micromolar range. Neutrophils did not migrate toward procalcitonin or calcitonin, nor was their oxygen free radical release affected as measured fluorimetrically. Checkerboard analysis of monocyte locomotion revealed procalcitonin-induced migration as true chemotaxis. Pretreatment of monocytes with procalcitonin or calcitonin rapidly deactivated their migratory response to formyl-Met-Leu-Phe, and both also induced homologous deactivation of migration. Procalcitonin elevated levels of cyclic adenosine monophosphate in monocytes. Conclusions: In vitro procalcitonin is a monocyte chemoattractant that deactivates chemotaxis in the presence of additional inflammatory mediators. Procalcitonin stimulates cyclic adenosine monophosphate production in monocytes, suggesting that its action may be specific and comparable with calcitonin, which exerts similar functions.