Human neutrophil migration into skin chambers is associated with production of NAP-1/IL8 and C5a

Respiratory burst activity initiated by the chemoattractants fMLP, rC5a and rNAP-1/IL8 was investigated in human exudated and peripheral blood neutrophils. Exudated cells were isolated after migration into a skin chamber and the respiratory burst activity was measured as chemiluminescence amplified by luminol and horseradish peroxidase. The response to fMLP (5 x 10(-8) mol/l) was significantly enhanced (p less than 0.01) in the exudated cells but was significantly decreased after stimulation (5 x 10(-8) mol/l) with rC5a and rNAP-1/IL8 (p less than 0.05 and p less than 0.01, respectively). Analysis revealed that, in the chamber fluid, the activated complement C5a was generated during exudation (p less than 0.01). Determinations of NAP-1/IL8 showed that this substance was also produced and released into the chamber fluid (p less than 0.01). No correlation was found between the number of exudated cells and the amount of C5a or NAP-1/IL8 in the exudation fluid, thus indicating that, in vivo, the exudation process is controlled by multiple factors and not by the quantity of a single chemoattractant. The present study shows that NAP-1/IL8 and C5a are produced in humans during an aseptic inflammation, and that this occurs in parallel to the migration of neutrophils into the skin chambers. The significant desensitization of the exudated cells to NAP-1/IL8 and C5a reflects a previous exposure to these attractants. These results suggest that the novel tissue-derived cytokine NAP-1/IL8 plays a role in human neutrophil exudation in vivo.