Functional properties of a novel neutrophil chemotactic factor derived from human monocytes

The effect of interleukin-8 and granulocyte macrophage colony stimulating factor on the response of neutrophils to formyl methionyl leucyl phenylalanine

Neutrophils isolated from patients with chronic bronchitis and emphysema have been shown to have enhanced responses to formyl peptides when assessed in vitro compared to age, sex matched controls. It is currently unclear whether the observed differences are due to a 'priming' effect by a second agent in vivo, or whether this is a primary difference in the neutrophils. We have studied the effects of interleukin-8, which is thought to be one of the major pro-inflammatory cytokines in chronic lung disease and granulocyte macrophage colony stimulating factor (GMCSF), in order to assess their effects on neutrophil chemotaxis and connective tissue degradation. In addition, we have assessed the effect of preincubation of these agents with neutrophils for 30 min followed by stimulation with F-Met-Leu-Phe (FMLP) to investigate any possible 'priming' effect that may be relevant to our clinical data. We report suppression of neutrophil chemotaxis to FMLP following incubation of the neutrophils with both IL-8 and GMCSF. However, we have observed an additive effect of IL-8 and FMLP for neutrophil degranulation leading to fibronectin degradation. The results suggest that IL-8 does not 'prime' neutrophils for subsequent FMLP stimulation as observed in vivo. Although the results for GMCSF were similar for the chemotactic response, the agent also had a synergistic effect on connective tissue degradation. However, it is concluded that neither agent could explain the enhanced neutrophil responses seen in our patients.

Interleukin-8 and GRO alpha prime human neutrophils for superoxide anion production and induce up-regulation of N-formyl peptide receptors

Interleukin-8 (IL-8) and GRO alpha are leukocyte-attracting peptides of the chemokine family. To study the priming potential of these chemokines, we measured superoxide anion production and up-regulation of N-formyl peptide receptors in human neutrophils. IL-8 and GRO alpha themselves did not stimulate production of significant amounts of superoxide anions but potentiated N-formyl peptide-induced superoxide anion production in a concentration-dependent manner. Binding measurements by flow cytometry at 37 degrees C with fluorescein-labeled N-formyl peptide revealed enhanced total N-formyl peptide binding after pretreatment of neutrophils with IL-8 and GRO alpha. Binding measurements performed at 4 degrees C indicated that the chemokines stimulated the up-regulation of N-formyl peptide receptors at the cell surface but did not alter their affinity for the ligand. This study indicates that IL-8 and GRO alpha, in addition to their known chemotactic activity, prime neutrophils for superoxide anion production, presumably by up-regulating the number of receptors for strong superoxide-anion-triggering stimuli.

Crystallization and preliminary X-ray crystallographic study of interleukin-8

Interleukin-8 (neutrophil-activating factor; NAP-1) has been crystallized by the vapour diffusion technique to give single crystals suitable for three-dimensional structural study at a resolution higher than 2.4 A. The crystals belong to the space group P3(1)21 or P3(2)21 and have unit cell dimensions a = b = 40.9 A, c = 90.3 A.

Inhibition of chemotactic migration of human neutrophilic granulocytes by recombinant human granulocyte-macrophage colony-stimulating factor

Human recombinant granulocyte-macrophage colony-stimulating factor (GM-CSF) was analysed for effects on the migration of human neutrophilic granulocytes by the Boyden chamber assay. At concentrations ranging from 0.1 to 10,000 U/ml (or 10(-12) to 10-mol/l) GM-CSF had neither chemokinetic nor chemotactic activity. When added to the cells in the upper compartment of the chamber GM-CSF dose-dependently inhibited the chemotactic migration towards the tripeptide f-Met-Leu-Phe and the complement split product C5a. Chemotaxis towards f-Met-Leu-Phe was inhibited more efficiently by GM-CSF than C5a-induced migration.