interleukin-8 and modipafant

The production of interleukin-8 by neutrophils in response to particulate stimuli may play a role in the recruitment and activation of further neutrophils in an inflammatory reaction. Here, we have evaluated the sequence of early events leading to interleukin-8 production by phagocytosing neutrophils. Kinetic experiments showed that the phagocytosis of zymosan particles by human neutrophils was rapid in onset. In contrast, interleukin-8 production was more protracted and only detectable 6 h later. Nevertheless, inhibition of phagocytosis with cytochalasins B or D suppressed the late interleukin-8 production. Activation of neutrophils with zymosan failed to enhance CD11/CD18 expression on the neutrophil surface but led to an increase in the expression of an activation-dependent epitope on CD11/CD18. Pretreatment with the platelet-activating factor (PAF) receptor antagonist, UK-74505 (4-(2-chlorophenyl)-1,4-dihydro-3-ethoxycarbonyl-6-methyl-2-[4-(2-methylimidazol[4,5-c]pyrid-1-yl)phenyl]-5-[N-(2-pyridyl)carbamoyl]pyridine), significantly blocked the increase in the expression of the activation epitope, resulting in inhibition of the phagocytosis of zymosan and interleukin-8 production. In conclusion, the activation of neutrophils with zymosan leads to the activation of PAF receptors and this is followed by activation of CD11/CD18, phagocytosis of zymosan particles and subsequent interleukin-8 release.

Topics: CD11 Antigens; CD18 Antigens; Cells, Cultured; Cytochalasins; Dihydropyridines; Epitopes; Humans; Imidazoles; Interleukin-8; Neutrophil Activation; Neutrophils; Phagocytosis; Platelet Membrane Glycoproteins; Receptors, Cell Surface; Receptors, G-Protein-Coupled; Time Factors; Zymosan

The aim of the present study was to investigate directly and characterize the ability of IL-1 beta in inducing eosinophil accumulation in vivo. For this purpose, we studied the recruitment of 111In-labeled eosinophils in rat skin in response to intradermally injected rat rIL-1 beta. Rat rIL-1 induced a dose-dependent accumulation of 111In-labeled eosinophils, with the maximal response being detected at 5 x 10(-13) mol/site. This response was slow in onset, progressively increasing over the 4-h period investigated. Rat rIL-1 also induced a small level of edema, as measured by the local accumulation of i.v. 125I-labeled albumin, which developed with a time course similar to that of 111In-labeled eosinophil accumulation. Co-administration of the cytokine with the IL-1R antagonist, IL-1ra, or actinomycin D, significantly inhibited the 111In-labeled eosinophil accumulation, and reduced the edema formation, induced by rat rIL-1. In addition, the 111In-labeled eosinophil accumulation was significantly suppressed in animals treated with the PAF antagonist UK-74,505 or an anti-human IL-8 mAb DM/C7. These observations demonstrate for the first time that IL-1 beta is a potent inducer of eosinophil accumulation in vivo. Moreover, the results reveal that this activity of IL-1 beta is receptor mediated and dependent on the induction of proteins that may be involved in the local generation of secondary inflammatory mediators including PAF and an IL-8-like molecule. These findings are consistent with the view that endogenously generated IL-1 may play an important role in the recruitment of eosinophils at sites of allergic inflammation.

Topics: Animals; Antibodies, Monoclonal; Calcium; Chemotaxis, Leukocyte; Dactinomycin; Dihydropyridines; Edema; Eosinophils; Imidazoles; Interleukin 1 Receptor Antagonist Protein; Interleukin-1; Interleukin-8; Leukotriene B4; Male; Platelet Activating Factor; Rats; Rats, Sprague-Dawley; Sialoglycoproteins; Skin