Recombinant Human Interleukin-8 Research Articles

Recombinant Human Interleukin-8 Is a Potent Activator of Canine Neutrophil Aggregation, Migration, and Leukotriene B4 Biosynthesis

Interleukin-8 (IL-8), formerly known as NAP-1, is formed by a variety of cells upon stimulation with IL-1 or tumor necrosis factor (TNF). The biologic activity of the cytokine involves activation of almost every neutrophil function studied so far in different species. In the present study, we compared the effects of recombinant human IL-8 (rIL-8) and the lipid mediators, leukotriene B4 (LTB4) and platelet-activating factor (PAF), on neutrophil functions in dogs. All three chemotactic factors induced neutrophil aggregation and chemotaxis, with rIL-8 being far more potent than LTB4 and PAF. The migration induced by rIL-8 was significantly greater than that observed towards LTB4 and PAF. In the aggregation assay, rIL-8 was shown for the first time to be a potent stimulant. The aggregation response was more persistent than that obtained with LTB4 and PAF and the potency of rIL-8 was greater. An intradermal dose-response study showed that rIL-8 is an extremely potent inducer of selective neutrophil infiltration in canine skin. The infiltration was more pronounced than following injection of LTB4 or PAF. It was proposed that the superior effect of rIL-8 was caused by a synergistic effect between injected rIL-8 and LTB4, which was shown to be produced in biologically active amounts by canine neutrophils stimulated with rIL-8. From a therapeutic point of view, the simultaneous presence of rIL-8 and LTB4 in inflammatory skin diseases highlights the need to develop drugs that inhibit the production and/or effect of both mediators.

Sandwich Elisa for Detection of Picogram Quantities of Interleukin-8

A sensitive sandwich enzyme-linked immunosorbent assay (ELISA) was developed for interleukin-8 (IL-8), a neutrophil chemoattractant and activator. A polyclonal antibody to recombinant human IL-8 was raised in rabbits, and the IgG was isolated from the antisera using a protein A column. Native and biotinylated forms of this antibody served as the capture antibody and developing antibody for the ELISA, respectively, and avidin-conjugated horse radish peroxidase provided the means for enzymatic color development. The lower limit of sensitivity for the assay was found to be 84 +/- 20 pg/ml IL-8 (mean +/- SD for 10 determinations). An inter-assay variability of 15-29% and an intra-assay variability of 12% were observed. The assay was able to detect IL-8 when the samples were prepared in either normal saline, RPMI, or human plasma. The development of this rapid, sensitive assay should provide a means to more fully evaluate the role of this cytokine in diverse disease states.

Endothelial interleukin-8: a novel inhibitor of leukocyte-endothelial interactions.

Certain inflammatory stimuli render cultured human vascular endothelial cells hyperadhesive for neutrophils. This state is transient and reversible, in part because activated endothelial cells secrete a leukocyte adhesion inhibitor (LAI). LAI was identified as endothelial interleukin-8 (IL-8), the predominant species of which is an extended amino-terminal IL-8 variant. At nanomolar concentrations, purified endothelial IL-8 and recombinant human IL-8 inhibit neutrophil adhesion to cytokine-activated endothelial monolayers and protect these monolayers from neutrophil-mediated damage. These findings suggest that endothelial-derived IL-8 may function to attenuate inflammatory events at the interface between vessel wall and blood.