title: Methodological aspects of assessing phagocytosis of Vibrio anguillarum by leucocytes of gilthead seabream (Sparus aurata L.) by flow cytometry and electron microscopy.
abstract: In this paper we optimize a flow cytometric method for evaluating the phagocytic activity of leucocytes in gilthead seabream (Sparus aurata L.) and characterize the phagocytic cells observed. Optimal conditions were established for the fluorescein-labelling and analysis of the bacterium Vibrio anguillarum by flow cytometry. Head-kidney leucocytes were incubated with the heat-killed fluorescein isothiocyanate (FITC)-labelled bacteria for different periods, during which the kinetics of phagocytosis was studied. Attached and interiorized bacteria were distinguished. Although phagocytic ability reached a maximum after 60 min, phagocytic capacity reached its maximum at 20 min. The amount of ingested bacteria per phagocyte was estimated from the mean fluorescence of the leucocytes. Cytochalasin B or colchicine was used to inhibit phagocytosis. Monocyte-macrophages and acidophilic granulocytes showed phagocytic activity as demonstrated by transmission electron microscopy. In conclusion, the technique presented allows the screening of thousands of cells, and individual cell evaluation, by quantifying interiorized particles in fish phagocytes. Our ultrastructural results demonstrate that V. anguillarum is actively phagocytized by seabream macrophages and acidophilic granulocytes.
authors.affiliation: Department of Cell Biology, Faculty of Biology, University of Murcia, E-30100 Murcia, Spain.
authors.forename: M A
authors.initials: MA
authors.lastname: Esteban
authors.forename: V
authors.initials: V
authors.lastname: Mulero
authors.forename: J
authors.initials: J
authors.lastname: Muñoz
authors.forename: J
authors.initials: J
authors.lastname: Meseguer
mesh_terms: D000818:Animals; D003078:Colchicine / Q000494:pharmacology; D003571:Cytochalasin B / Q000494:pharmacology; D005434:Flow Cytometry; D016650:Fluorescein-5-isothiocyanate; D005456:Fluorescent Dyes; D006098:Granulocytes / Q000276:immunology* / Q000382:microbiology / Q000648:ultrastructure; D007700:Kinetics; D008264:Macrophages / Q000276:immunology* / Q000382:microbiology / Q000648:ultrastructure; D008854:Microscopy, Electron; D010473:Perciformes / Q000276:immunology*; D010587:Phagocytosis / Q000187:drug effects / Q000276:immunology*; D014733:Vibrio / Q000276:immunology*
chemical_list: D005456:Fluorescent Dyes; D003571:Cytochalasin B; D016650:Fluorescein-5-isothiocyanate; D003078:Colchicine