Immunocytochemical localization of pleurocidin to the cytoplasmic granules of eosinophilic granular cells from the winter flounder gill

Abstract

The teleost gill is considered to be of significant immunological importance, as it is one of the first tissues exposed to environmental or pathogenic challenge and thus should be well equipped to mount an effective immune response. This study characterizes ultrastructurally and immunocytochemically a tissue granulocyte (eosinophilic granular cell) from the winter flounder gill that was previously determined to be involved in the gene expression and synthesis of a known antimicrobial peptide (pleurocidin). The cell is irregular in shape with a cytoplasm characterized by numerous large, electron‐dense, membrane‐bounded granules. The nucleus is euchromatic and closely associated with a prominent rough endoplasmic reticulum. The cytoplasm typically contains two to three mitochondria and a centralized Golgi apparatus surrounded by numerous electron‐lucent vesicles. Immunogold staining of the cells with an anti‐pleurocidin antibody shows large number of gold particles in direct association with the electron‐dense granules. These data provide the first evidence definitively showing storage of an antimicrobial peptide in the cytoplasmic granules of an eosinophilic granule cell resident in gill tissue.

Prevalence, Intensity, and Abundance of Infection and Pathogenesis Caused by Diphyllobothriosis in Vulnerable, Native Fish and Introduced Trout in Lake Panguipulli, Chile

“…Apparently, most teleost fish exhibit these cells in various organs, with properties similar to mast cells of mammals (Dezfuli et al, 2008). Several studies indicate that these cells degranulate in response to pathogens, thus affecting vascular permeability and suggesting that their products act in the induction of the host's inflammatory response: vasodilatation, recruitment of neutrophils, migration and activation of macrophages, and production of neuromodulators, enzymes, or antimicrobial peptides (Dezfuli et al, 2000(Dezfuli et al, , 2008Schmale et al, 2004;Murray et al, 2007).…”

The inflammatory response of fish to helminth parasites

“…Other authors have detected specific neuromodulators (Dezfuli et al, 2000a) and enzymes including lysozyme (Sveinbjørnsson et al, 1996) within the granules of mast cells from fish exposed to infection by parasites and bacteria. Recently, specific antimicrobial peptides have been localized to mast cells (Silphaduang & Noga, 2001;Iijima et al, 2003;Murray et al, 2003Murray et al, , 2007. It is hoped that information provided by this paper will spur further research, nonetheless, the following investigations would contribute significantly to our knowledge about the RCs and mast cells in teleost.…”

“…Above similarities and response to known mast cell degranulating agents (i.e. Compound 48/80) and effects on vascular permeability have led investigators to suggest a role for these cells in the induction of inflammatory responses (Murray et al, 2007). These include vasodilatation, neutrophil attraction and migration and macrophage activation (Vallejo & Ellis, 1989;Powell et al, 1991;Matsuyama & Iida, 2001).…”

An Overview of the Immunological Defenses in Fish Skin

“…Mast cells, also known as eosinophilic granular cells (EGCs), are present in most species of teleosts and are found in a variety of tissues, including the skin, gut, gills, brain, and in the vicinity of blood vessels [244][245][246][247][248]. Mast cells may play an important role in the mechanisms of inflammatory response because they express a number of functional proteins, including antimicrobial peptides that act against a broad spectrum of pathogens [249][250][251][252][253].…”