Abstract
OBJECTIVES: As auranofin resembles some neutrophil activating sulphur containing compounds, it was decided to investigate whether it had activating effects on neutrophil migration in addition to the published inhibitory effects. METHODS: The Boyden chamber assay was used to determine the migration velocity of human neutrophils. The difference between chemotaxis and chemokinesis was established with a chequerboard assay. RESULTS: Low concentrations of auranofin stimulated human neutrophil migration; concentrations of auranofin higher than 1 mumol/l were inhibitory. Inhibitors of leukotriene formation, or of protein kinase C, had the same effect on auranofin induced potentiation of migration as on fMLP activated migration. Auranofin, at a concentration of 100 nmol/l, caused a transient increase in the cGMP level of neutrophils. The auranofin induced increase in migration was strongly inhibited by methylene blue and by LY83583, two inhibitors of cGMP accumulation. CONCLUSIONS: The auranofin induced enhancement of migration is partly due to a chemokinetic effect, but mainly due to a chemotactic effect. The potentiating effect of auranofin on migration is not specifically due to the ability of the drug to inhibit protein kinase C activity or to generate leukotrienes. These results suggest that the enhancement of neutrophil migration by low levels of auranofin is related to the enhancement of cGMP levels in neutrophils.