title: Leucocyte recruitment induced by type II phospholipases A(2) into the rat pleural cavity.
abstract: Bothropstoxin-I (BthTX-I) and bothropstoxin-II (BthTX-II) are Lys-49 and Asp-49 phospholipases A(2) (PLA(2)s), respectively, isolated from Bothrops jararacussu venom. Piratoxin-I (PrTX-I) is a Lys-49 PLA(2) isolated from Bothrops pirajai venom. In this study, the ability of BthTX-I, BthTX-II and PrTX-I to recruit leucocytes into the rat pleural cavity and potential mechanisms underlying this effect were investigated. Intrapleural injection of either BthTX-I or PrTX-I (10-100 microg/cavity each) caused a significant leucocyte infiltration at 12 h after injection. The maximal cell migration was observed with the dose of 30 microg/cavity (14.9+/-15.5 and 17.6+/-1. 6x10(6) cells/cavity, respectively). Leucocyte counts consisted mainly of mononuclear cells, but significant amounts of neutrophils and eosinophils were also observed. Intrapleural injection of BthTX-II (10-100 microg/cavity) caused a marked leucocyte infiltration at 6 and 12 h after injection. The maximal response was observed with the dose of 100 microg/cavity (57.3+/-3.4x10(6) cells/cavity, 6 h). The leucocyte counts were mainly composed of neutrophils and mononuclear cells. The treatment of either BthTX-I (30 microg/cavity, 12 h) or BthTX-II (30 microg/cavity, 6 h) with the PLA(2) inhibitor p-bromophenacyl bromide (p-BPB) had no effect on the total and differential leucocyte counts induced by these proteins. The same treatment partially reduced the PrTX-I-induced pleural leucocyte infiltration. In rats depleted of the histamine and 5-hydroxytryptamine (5-HT) stores by chronic treatment with compound 48/80, the total leucocyte counts in response to BthTX-I, BthTX-II and PrTX-I was not significantly affected compared to control animals. In addition, BthTX-I, BthTX-II and PrTX-I (100 microg/ml each) significantly degranulated pleural mast cells in vitro leading to the release of [(14)C]5-hydroxytryptamine ([(14)C]5-HT). p-BPB and heparin (50 IU/ml) significantly reduced the [(14)C]5-HT release induced by these PLA(2)s. Our results demonstrate that BthTX-I, BthTX-II and PrTX-I recruit leucocyte into the pleural cavity of the rat by mechanisms unrelated to enzymatic activity and pleural mast cell degranulation.
authors.affiliation: Department of Pharmacology, Faculty of Medical Sciences, UNICAMP, PO Box 6111, 13081-970, (SP), Campinas, Brazil.
authors.forename: R C
authors.initials: RC
authors.lastname: de Castro
authors.forename: E C
authors.initials: EC
authors.lastname: Landucci
authors.forename: M H
authors.initials: MH
authors.lastname: Toyama
authors.forename: J R
authors.initials: JR
authors.lastname: Giglio
authors.forename: S
authors.initials: S
authors.lastname: Marangoni
authors.forename: G
authors.initials: G
authors.lastname: De Nucci
authors.forename: E
authors.initials: E
authors.lastname: Antunes
mesh_terms: D000098:Acetophenones / Q000494:pharmacology; D000818:Animals; D015550:Cell Degranulation / Q000187:drug effects; D002634:Chemotaxis, Leukocyte / Q000187:drug effects*; D003435:Crotalid Venoms / Q000494:pharmacology; D004804:Eosinophils / Q000502:physiology*; D054501:Group II Phospholipases A2; D006632:Histamine / Q000378:metabolism; D007958:Leukocyte Count; D008297:Male; D008407:Mast Cells / Q000166:cytology / Q000187:drug effects; D009504:Neutrophils / Q000502:physiology*; D010741:Phospholipases A / Q000494:pharmacology*; D010994:Pleura / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D030162:Reptilian Proteins; D012701:Serotonin / Q000378:metabolism; D003189:p-Methoxy-N-methylphenethylamine / Q000494:pharmacology
chemical_list: D000098:Acetophenones; D003435:Crotalid Venoms; D030162:Reptilian Proteins; C078097:bothropstoxin; D012701:Serotonin; D003189:p-Methoxy-N-methylphenethylamine; D006632:Histamine; C114085:piratoxin I; D010741:Phospholipases A; D054501:Group II Phospholipases A2; C072031:bothropstoxin II; C006821:4-bromophenacyl bromide