Activation of guinea pig eosinophils by human recombinant IL-5. Selective priming to platelet-activating factor-acether and interference of its antagonists.
The potential role of platelet-activating factor (PAF)-acether and of IL-5 as an eosinophil-proliferating, activating, and/or recruiting mediator in asthma led us to study the effects of human (h) rIL-5 (hrIL-5) and PAF-acether, alone or combined, on isolated guinea pig eosinophils. Two populations of eosinophils were separated from peritoneal lavages of polymyxin B-treated guinea pigs upon a discontinuous metrizamide gradient: one of low density (between 20 and 22% of metrizamide, purity: 63 +/- 3%, n = 27) and another of normal density (between 22 and 24% of metrizamide, purity: 87 +/- 2%, n = 16). Chemotactic activity was evaluated on a micro-Boyden chamber, results being expressed as the number of migrating eosinophils (mean +/- SEM) at 40 microns through a cellulose nitrate filter (3 microns pore size) in the presence of the agonist or of the solvent alone. hrIL-5 dose-dependently stimulated normodense eosinophil chemotaxis, reaching a peak at 500 ng/ml (98 +/- 21 migrating eosinophils, n = 5, p less than 0.05). These eosinophils also responded to PAF-acether and to LTB4 and not to FMLP, hrTNF alpha, and LPS. Eosinophil preincubation with hrIL-5 increased significantly the migration by PAF-acether (173 +/- 23 migrating eosinophils with PAF-acether 10 nM after preincubation with hrIL-5 500 ng/ml vs 69 +/- 10 after preincubation with buffer alone, p less than 0.01) and failed to enhance migration by LTB4 or to uncover an activity for FMLP. Migration by PAF-acether was antagonized when the cells were preincubated with the antagonists BN 52021 and WEB 2086, which also inhibited migration by hrIL-5. Eosinophils were auto-desensitized by and to PAF-acether or LTB4, but were not cross-desensitized to each other. Eosinophils desensitized to PAF-acether failed to migrate with hrIL-5, but those desensitized to LTB4 responded to hrIL-5 as controls. hrIL-5 failed to induce the elevation of intracellular free calcium concentration and superoxide anion generation from basal values, whereas preincubation of eosinophils with hrIL-5 induced a significant increase in the rise in intracellular free calcium concentration and in superoxide anion generation by 10 nM PAF-acether but not by LTB4. In conclusion, the in vivo eosinophil migration in allergy may involve hrIL-5, particularly associated to PAF-acether.
Coëffier
E
E
Unité de Pharmacologie Cellulaire, Unité Associée Institut Pasteur-INSERM no. 285, Paris, France.
Joseph
D
D
Vargaftig
B B
BB
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002465:Cell Movement / Q000187:drug effects; D004224:Diterpenes; D004804:Eosinophils / Q000187:drug effects*; D046934:Ginkgolides; D006168:Guinea Pigs; D006801:Humans; D015848:Interleukin-5 / Q000494:pharmacology*; D007783:Lactones / Q000494:pharmacology; D007975:Leukotriene B4 / Q000494:pharmacology; D008070:Lipopolysaccharides; D010972:Platelet Activating Factor / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000494:pharmacology*; D011994:Recombinant Proteins / Q000494:pharmacology; D013481:Superoxides / Q000378:metabolism
D004224:Diterpenes; D046934:Ginkgolides; D015848:Interleukin-5; D007783:Lactones; D008070:Lipopolysaccharides; D010972:Platelet Activating Factor; D011994:Recombinant Proteins; D013481:Superoxides; D007975:Leukotriene B4; C045856:ginkgolide B; D002118:Calcium