title: A sequential study of incomplete Freund's adjuvant-induced peritonitis in Atlantic cod.
abstract: Development of diagnostic and prophylactic methodologies is dependent on knowledge of the host's defence system and reaction to different vaccine adjuvants. Here we present a sequential morphological study of peritonitis and inflammatory cell processing of incomplete Freund's adjuvant (IFA) in intraperitoneally injected Atlantic cod. The peritoneal tissue responses were characterised using necropsy, histology and electron microscopy. An extensive inflammatory response as characterised by leukocyte morphology and contents of enzymes, presence of apoptotic cells and IFN-γ-expressing cells was observed. Three days post injection, IFA droplets were surrounded by different types of inflammatory cells and two different patterns could be discerned. The first was characterised by flattened and concentrically arranged interdigitating cells connected by desmosomes and with macrophage-like cells (MLCs) predominant in the periphery. The second type possessed four stratified layers with an inner layer containing many apoptotic MLCs; a second layer containing flattened and shrunken cells and outer layers comprising moderately flattened cells and an outermost layer of mononuclear cells expressing IFN-γ. Oil was detected both inside and outside MLCs. The two types of processes, of which the second was clearly stratified, were similar to those observed in other teleosts, indicating a variety of reaction modes or alternatively sequential process development. The numerous dead MLCs contributed to inflammation.
authors.affiliation: Norwegian Veterinary Institute, P.O. Box 750 Dep., N-0106 Oslo, Norway. mona.gjessing@vetinst.no
authors.forename: Mona Cecilie
authors.initials: MC
authors.lastname: Gjessing
authors.forename: Knut
authors.initials: K
authors.lastname: Falk
authors.forename: Simon Chioma
authors.initials: SC
authors.lastname: Weli
authors.forename: Erling Olaf
authors.initials: EO
authors.lastname: Koppang
authors.forename: Agnar
authors.initials: A
authors.lastname: Kvellestad
mesh_terms: D000818:Animals; D005393:Fish Diseases / Q000139:chemically induced* / Q000276:immunology / Q000401:mortality / Q000473:pathology*; D005620:Freund's Adjuvant; D048389:Gadus morhua / Q000276:immunology*; D007371:Interferon-gamma / Q000276:immunology; D008055:Lipids; D046529:Microscopy, Electron, Transmission; D010538:Peritonitis / Q000139:chemically induced / Q000276:immunology / Q000401:mortality / Q000473:pathology / Q000662:veterinary*; D012333:RNA, Messenger / Q000378:metabolism; D013696:Temperature
chemical_list: D008055:Lipids; D012333:RNA, Messenger; C114843:incomplete Freund's adjuvant; D007371:Interferon-gamma; D005620:Freund's Adjuvant