Serum exposed to nanoparticle carbon black displays increased potential to induce macrophage migration

To assess whether fine and ultrafine particles (nanoparticles) have the capacity to activate factors in serum that would induce macrophage migration. This is a model previously reported to investigate complement activation by other respirable particles and fibres.

Foetal bovine serum was exposed to varying doses of fine and nanoparticle carbon black as well as the oxidant tert-butyl hydroperoxide (tBHP). The subsequent potential of the serum to induce macrophage migration was measured using a macrophage chemotaxis assay.

Treatment of serum with 10 mg/ml of nanoparticle carbon black generated substances that induced a 1.8-fold increase in macrophage migration (P<0.001) compared with untreated serum. This effect was partially inhibited by antioxidant intervention. Serum treated with an equivalent mass of fine carbon black did not display any chemotactic potential. tBHP treatment of the serum did not result in the generation of macrophage chemotactic factors.

High doses of nanoparticle carbon black have the capacity to cause chemotactic factor generation in serum, by a mechanism involving ROS generation, although ROS alone, in the form of tBHP are not adequate to generate chemotactic factors in serum.