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ARS Home » Southeast Area » Stoneville, Mississippi » Warmwater Aquaculture Research Unit » Research » Publications at this Location » Publication #398631
Research Project: Improving the Productivity and Quality of Catfish Aquaculture

Location: Warmwater Aquaculture Research Unit

Title: A subset of leukocyte immune-type receptors (LITR) regulates phagocytosis in channel catfish (Ictalurus punctatus) leukocytes

Author
item CRIDER, JONATHAN - University Of Mississippi Medical Center
item WILSON, MELANIE - University Of Mississippi Medical Center
item FELCH, KRISTIANNA - University Of Mississippi Medical Center
item DUPRE, REBECCA - Department Of Energy
item Quiniou, Sylvie
item BENGTEN, EVA - University Of Mississippi Medical Center

Submitted to: Molecular Immunology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/15/2022
Publication Date: 2/1/2023
Citation: Crider, J., Wilson, M., Felch, K.L., Dupre, R.A., Quiniou, S., Bengten, E. 2023. A subset of leukocyte immune-type receptors (LITR) regulates phagocytosis in channel catfish (Ictalurus punctatus) leukocytes. Molecular Immunology. 154:33-44. https://doi.org/10.1016/j.molimm.2022.12.009.
DOI: https://doi.org/10.1016/j.molimm.2022.12.009

Interpretive Summary: Infectious diseases represent a major economic threat to the channel catfish industry. Ingestion (phagocytosis) of bacteria by white blood cells is an important immune function that helps to eliminate pathogens in all vertebrate animals. Researchers at the USDA, ARS Warmwater Aquaculture Research Unit and University of Mississippi Medical Center showed that two antibodies specific to catfish leukocyte immune-type receptors (LITRs) regulate phagocytosis/uptake in catfish white blood cells. One antibody stimulated uptake, while the other antibody inhibited phagocytosis. This is the first time LITR-mediated phagocytosis has been reported in fish. These LITR-specific antibodies may in the future be used to determine the natural targets (ligands) for phagocytic LITRs. These ligands may then be incorporated into vaccines and help stimulate better immune responses. This information helps understand how the catfish immune system functions and may help design better vaccines to protect fish.

Technical Abstract: Channel catfish, Ictalurus punctatus leukocyte immune-type receptors (LITRs) constitute a large family of paired, immunoregulatory receptors unique to teleosts. A role for LITRs in phagocytosis has been proposed based on studies in mammalian cell lines; however, LITR-mediated phagocytosis has not been examined in the catfish model. In this study, we use two anti-LITR monoclonal antibodies, CC41 and 125.2, to contrast the effects of crosslinking subsets of inhibitory and activating LITRs. Briefly, LITRs expressed by catfish 'd T cells, aß T cells, and macrophage cell lines were crosslinked using mAb-conjugated fluorescent microbeads, and bead uptake was evaluated by flow cytometry and confirmed by confocal microscopy. A clear difference in the uptake of 125.2- and CC41-conjugated beads was observed. Crosslinking LITRs with mAb 125.2 resulted in efficient bead internalization while mAb CC41 crosslinking of inhibitory LITRs resulted predominantly in a capturing phenotype. Pretreating catfish macrophages with mAb CC41 resulted in a marked decrease in LITR-mediated phagocytosis of 125.2-conjugated beads. Overall, these findings provide insight into fish immunobiology and validate LITRs as regulators of phagocytosis in catfish macrophages and 'd T cells.