The Quantitative Clearance of Bacteria from the Bloodstream of Rainbow Trout (Salmo gairdneri)

Abstract

Abstract. The blood clearance of 51Cr-labelled heat-killed Salmonella pullorurn was biphasic and exponential for each phase. This pattern was the same for all three concentrations of bacteria used. The initial more rapid phase lasted for approximately 15 minutes when roughly 90% of the bacteria had been cleared. The second slower phase started 25 to 30 minutes post-inoculation and lasted for approximately 25 to 30 minutes. The tissue distribution of bacteria showed that in both absolute and relative terms, the kidney was the most important organ, accounting for more than 70% uptake of the bacteria.These kinetics demonstrate that rainbow trout at 8°C are able to clear their bloodstream of Salmonella very efficiently, in a fashion very similar to mammals. It is not known, however, which of the various possible clearance mechanisms dominates each phase.Fish are becoming increasingly important both in terms of their farming potential (aquaculture) and the possibility of their use as sentinels for detecting environmental pollution. Many of the more economically serious diseases of fish are bacterial, and yet little is known about the in vivo fate of su:h pathogens.Many workers have emphasized the efficiency of the reticuloendothelial system in clearing the bloodstream [27] and the kinetics of the clearance of particulate matter (both inert colloids and bacteria) usually has been accepted as a direct measure of this phagocytic efficiency [29]. Despite substantial work on reticuloendothelial kinetics in mammals, there is little knowledge of the subject in teleost fish, or ectothermic vertebrates in general. Indeed, we can find only one report describing in vivo rates of reticuloendothelial clearance in fish-in the goldfish (Curussius uurutus), lamprey (PetromyconJluviutiZis)7 and dogfish (Scylliorhinus caniculus) [25].The histological and ultrastructural location and distribution of intravenously and intraperitoneally injected vital dyes and other particles have been studied in several fish species [lo, 11, 17,23, 24,3 I]. These studies represent in broad terms a "mapping outy7 of the fish reticuloendothelial system in both fresh and saltwater species, ranging from primitive to advanced members of the group.Briefly, these studies (largely using colloidal carbon) showed that in teleosts, the spleen and kidney (both anterior and posterior) were important reticuloendothelial 687

Early innate immune response and redistribution of inflammatory cells in the bony fish gilthead seabream experimentally infected with Vibrio anguillarum

“…Indeed, several studies have reported, in the HK, the uptake of particulate and soluble antigen whether injected i.v. (Ferguson et al 1982;Stensvåg et al 1999) or i.p. (Arnesen et al 2002;Grove et al 2003) being accompanied or not accompanied by a higher number of Ig-producing cells compared with control fish.…”

“…At the same time, the HK also serves as a secondary lymphoid organ (a lymph node analogue) in the induction and elaboration of immune responses (Kaattari and Irwin 1985) and in the clearance of soluble (Stensvåg et al 1999) and particulate (Ferguson et al 1982) antigen from the bloodstream. The spleen of teleosts has also been implicated in the clearance of blood-borne substances and immune complexes in specialised terminations of arterioles, called ellipsoids (Espenes et al 1995(Espenes et al , 1997Arnesen et al 2002).…”

The morphology of the immune system in teleost fishes

“…When radiolabelled bacteria are injected into rainbow trout, more than 70% of the radioactivity is found in the kidney (Ferguson et al, 1982). The sinusoidal macrophages and the endothelial cells of the head kidney sinusoids participate in the trapping of particles and substances from the bloodstream (MacArthur et al, 1983;Dannevig et al, 1994;Brattgjerd & Evensen, 1996) (Fig.…”

Endocytosis via the scavenger- and the mannose-receptor in rainbow trout (Salmo gairdneri) pronephros is carried out by nonphagocytic cells

“…The kidney of teleost fishes participates in clearing the blood of various foreign substances (Ferguson et al 1982;MacArthur et al 1983). Several reports have demonstrated phagocytic uptake of microorganisms in fish kidney macrophages (Braun-Nesje et al 1982;Johnson and Smith 1984;Ferguson 1984).…”