The effects of interleukin‐8 on neutrophil fMetLeuPhe receptors, CD11b expression and metabolic activity, in comparison and combination with other cytokines

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Abstract
The effect of the chemotactic cytokine, IL-8, on neutrophil function was compared with that of of other cytokines, GM-CSF, G-CSF TNF alpha and IFN-gamma. IL-8 rapidly stimulated a three-fold enhancement of the fMLP-stimulated respiratory burst, but this priming effect was transient compared with the slower and sustained effects of GM-CSF and IFN gamma. Apart from G-CSF, IL-8 was the weakest priming agent and was weaker than GM-CSF in priming arachidonic acid metabolism stimulated by calcium ionophore. When incubated in combination, IL-8 and TNF alpha were highly synergistic in their effects on respiratory burst priming, whereas IL-8 and GM-CSF showed little synergy. In contrast, IL-8 was as potent as GM-CSF at increasing the expression of neutrophil chemotactic peptide receptors and the beta 2 integrin, CD11b. The latter was maximally upregulated within 5 min of stimulation with IL-8, whereas the effect of GM-CSF was much slower. The kinetics of neutrophil respiratory burst priming by IL-8 were the same when measured in whole blood samples and in purified cell suspensions, and IL-8 dose-response curves were similar, showing that the low affinity IL-8 receptors on erythrocytes do not rapidly sequester circulating IL-8. The data suggest that IL-8 plays a minor role in priming neutrophil function and that a more major activity is the regulation of neutrophil adhesion and migration.

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