Differential involvement of mussel hemocyte sub-populations in the clearance of bacteria

M-G Parisi, H Li, L Jouvet, Elizabeth Dyrynda, N Parrinello, M Cammarata, P Roch

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    58 Citations (Scopus)

    Abstract

    Mussels are filter-feeders living in a bacteria-rich environment. We have previously found that numerous bacterial species are naturally present within the cell-free hemolymph, including several of the Vibrio genus, whereas the intra-cellular content of hemocytes was sterile. When bacteria were injected into the circulation of the mussel, the number of living intra-hemocyte bacteria dramatically increased in less than an hour, suggesting intense phagocytosis, then gradually decreased, with no viable bacteria remaining 12 h post-injection for Micrococcus lysodeikticus, 24 h for Vibrio splendidus and more than 48 h for V ibrio anguillarum. The total hemocyte count (THC) was dramatically lowered by the bacterial injections, as quantified by flow cytometry. V. splendidus induced the strongest decreases with -66% 9 h post-injection of living bacteria and -56% 3 h post-injection of heat-killed bacteria. Flow cytometry was used to identify three main sub-populations of hemocytes, namely hyalinocytes, small granulocytes and large granulocytes. When THC was minimal, i.e. within the first 9 h post-injection, proportions of the three cell categories varied dramatically, suggesting differential involvement according to the targets, but small granulocytes remained the majority. According to a decrease in their number followed by an increase (+90% at 12 h with living V. splendidus), hyalinocytes also appeared to be involved as cellular effectors of antibacterial immunity, despite possessing little capacity for phagocytosis and not containing antimicrobial peptides. © 2008 Elsevier Ltd. All rights reserved.

    Original languageEnglish
    Pages (from-to)834-840
    Number of pages7
    JournalFish and Shellfish Immunology
    Volume25
    Issue number6
    DOIs
    Publication statusPublished - Dec 2008

    Keywords

    • Clearance
    • Flow cytometry
    • Granulocytes
    • Hyalinocytes
    • Micrococcus lysodeikticus
    • Molluscs
    • Mytilus
    • Vibrio anguillarum
    • Vibrio splendidus

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