title: Activation of carp leukocytes by a galactose-binding protein from Aphanomyces piscicida.
abstract: This study demonstrated that a galactose-binding protein (GBP) produced by a fish pathogenic water mold, Aphanomyces piscicida, activates carp leukocytes. Leukocytes were separated from the head kidney and peripheral blood using Percoll density centrifugation. A flow cytometric analysis revealed that GBP binds with many cells and a variety of cell types including lymphocytes, granulocytes and thrombocytes. Intracellular calcium flux of the peripheral blood leukocytes induced by stimulation with GBP was confirmed by counting the fluo-3 loaded cells whose fluorescence increased after the stimulation using flow cytometry. The percentage of cells in which a calcium flux was induced peaked 1 min after the stimulation. Approximately 6% of the cells specifically responded 1 min after the stimulation. The proliferation response was determined by the level of BrdU uptake by the leukocytes after the stimulation. Cell proliferation was observed 2, 4 and 6 days after stimulation with GBP. The expression of cytokines IL-1beta and TGF-beta1 in the peripheral blood leukocytes, after the stimulation was evaluated by a semi-quantitative reverse-transcriptase polymerase chain reaction. Increased expression of IL-1beta was observed 4h after stimulation with GBP. Variation of TGF-beta1 expression under the same conditions was not observed. The kinetics of intracellular calcium flux and the level of IL-1beta expression induced by GBP stimulation were different from those induced by phytohemagglutinin stimulation. These results confirmed that GBP is a pathogenic microbial component that can induce cell activation. GBP seems to induce the inflammatory response observed in the Aphanomyces infection.
authors.affiliation: Division of Fish Diseases, Nippon Veterinary and Animal Science University, 1-7-1 Kyonan-cho, Musashino, Tokyo 180-8602, Japan. oakurata@mud.biglobe.ne.jp
authors.forename: Osamu
authors.initials: O
authors.lastname: Kurata
authors.forename: Kishio
authors.initials: K
authors.lastname: Hatai
mesh_terms: D000818:Animals; D002118:Calcium / Q000097:blood / Q000276:immunology; D002135:Calcium-Binding Proteins; D002347:Carps / Q000097:blood / Q000276:immunology*; D002455:Cell Division / Q000187:drug effects / Q000276:immunology; D005434:Flow Cytometry; D015870:Gene Expression; D007375:Interleukin-1 / Q000032:analysis / Q000096:biosynthesis / Q000235:genetics; D007962:Leukocytes / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism; D009004:Monosaccharide Transport Proteins / Q000276:immunology* / Q000378:metabolism; D009868:Oomycetes / Q000276:immunology* / Q000378:metabolism; D033902:Periplasmic Binding Proteins; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016212:Transforming Growth Factor beta / Q000096:biosynthesis / Q000235:genetics
chemical_list: D002135:Calcium-Binding Proteins; D007375:Interleukin-1; D009004:Monosaccharide Transport Proteins; D033902:Periplasmic Binding Proteins; D012333:RNA, Messenger; D016212:Transforming Growth Factor beta; C023550:galactose-binding protein; D002118:Calcium