title: Interleukin-5 modulates interleukin-8 secretion in eosinophilic inflammation.
abstract: Serum and BALF (bronchoalveolar lavage fluid) IL-8 levels and serum levels were investigated in Toxocara canis infected guinea-pigs and the role of IL-5 as a modulator of cytokine secretion was studied. Serum levels increased early in infected animals, exceeding control levels 4 h after infection, peaked between days 6 and 18, and continued to exceed control levels after 48 days of infection. Serum and BALF IL-8 levels showed the same profile as blood eosinophilia, increasing 6 days post-infection and peaking between days 18 and 24. Treatment of infected animals with anti-IL-5 Ab suppressed eosinophilia with a parallel increase in blood IL-8 levels, whereas no change was found in levels. To support our in vivo observation we carried out experiments in vitro using guinea-pig LPS-stimulated adherent peritoneal cells which release large amounts of IL-8 into the supernatants. When rIL-5 was added to LPS-stimulated cells, 65% inhibition of IL-8 release into the supernatants was observed. Pre-incubation of cells with anti-IL-5 Ab prevented the inhibition of IL-8 release into the supernatants induced by rIL-5. Our results demonstrate for the first time that TNF-alpha and IL-8 are released concomitant with or after IL-5 in the eosinophilic inflammation induced by T. canis. Moreover, in addition to showing that IL-5 is fundamental for the induction of blood eosinophilia, the present results suggest that this cytokine may play a new biological role by acting as modulator of IL-8 secretion.
authors.affiliation: Department of Parasitology, Microbiology and Immunology, School of Medicine of Ribeirão Preto, University of São Paulo, Brazil. facciol@fmrp.usp.br
authors.forename: L H
authors.initials: LH
authors.lastname: Faccioli
authors.forename: A I
authors.initials: AI
authors.lastname: Medeiros
authors.forename: A
authors.initials: A
authors.lastname: Malheiro
authors.forename: R C
authors.initials: RC
authors.lastname: Pietro
authors.forename: A
authors.initials: A
authors.lastname: Januário
authors.forename: B B
authors.initials: BB
authors.lastname: Vargaftig
mesh_terms: D000818:Animals; D000906:Antibodies / Q000378:metabolism; D001772:Blood Cell Count; D001992:Bronchoalveolar Lavage Fluid; D015536:Down-Regulation; D004804:Eosinophils / Q000166:cytology / Q000276:immunology / Q000378:metabolism*; D005260:Female; D005269:Femur / Q000378:metabolism; D006168:Guinea Pigs; D015848:Interleukin-5 / Q000378:metabolism*; D016209:Interleukin-8 / Q000378:metabolism*; D017166:Toxocara canis / Q000276:immunology*; D014120:Toxocariasis / Q000097:blood / Q000276:immunology / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D000906:Antibodies; D015848:Interleukin-5; D016209:Interleukin-8; D014409:Tumor Necrosis Factor-alpha