MONOCYTE ACTIVATION ON TITANIUM-SPUTTERED POLYSTYRENE SURFACES IN-VITRO - THE EFFECT OF CULTURE CONDITIONS ON INTERLEUKIN-1 RELEASE

The release of interleukin-1 alpha (IL-1 alpha) by human peripheral bl ood monocytes cultured for 24 and 48 h on polystyrene (PS) and titaniu m-sputtered polystyrene (Ti) was evaluated. Magnetron sputtering of th e PS surfaces resulted in a formation of a 50-nm-thick coat, consistin g of an outer layer of TiO2. Monocytes released IL-1 alpha without the addition of exogenous stimuli. A doubling of the culture time from 24 to 48 h did not have a major effect on the amount of IL-1 alpha relea sed. The IL-1 alpha levels were increased by addition of lipopolysacch aride (LPS). High concentrations of PS particles (1 and 3 mu m diamete r) were equally effective stimuli for IL-1 alpha release as LPS. Pread sorption of fibronectin to culture plates augmented LPS-stimulated IL- 1 alpha secretion, whereas preadsorbed fibrinogen had an inhibitory ef fect. Our observations indicate a direct activation of monocytes by PS and Ti, resulting in IL-1 alpha secretion, which is modified by prote in adsorption and exogenous stimuli.