title: Defining terminally differentiating B cell populations in rainbow trout immune tissues using the transcription factor XbpI.
abstract: The nature of antibody-secreting cells in the rainbow trout is poorly defined. Here we describe a flow cytometric approach to help differentiate between four major trout B cell subsets present during terminal B cell differentiation: resting B cells, activated B cells, plasmablasts, and plasma cells. To aid in the identification of B cell subsets, the LPS-inducible transcription factor XbpI-S was used as a marker. An antibody specific to the stable form of inducible transcription factor X-box protein I (XbpI) was generated, which detects XbpI-S protein expression for species within the Oncorhyncus genus, including rainbow trout. Combinatorial expression patterns, or B cell signatures, were established using antibodies to XbpI-S, Pax5, and IgM in combination with a proliferation marker. We show that XbpI-S induction in trout splenic B cells increases throughout a 10-day in vitro LPS-induction period and that increased XbpI-S expression correlates with increased HCmu expression in the cell. PBLs displayed a lower level of XbpI-S induction during this incubation period, compared to spleen. We conclude that trout B cells follow a highly conserved B cell activation pathway, albeit slower than what has been observed in mammalian species. The use of XbpI-S as an activation marker for trout humoral immune activation promises to be useful for future in vivo studies, and can be applied to a broad range of teleost species.
authors.affiliation: Department of Biology, The College of William and Mary, Williamsburg, VA 23185, USA.
authors.forename: Maggie
authors.initials: M
authors.lastname: Barr
authors.forename: Katrina
authors.initials: K
authors.lastname: Mott
authors.forename: Patty
authors.initials: P
authors.lastname: Zwollo
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D016175:B-Lymphocyte Subsets / Q000276:immunology*; D015153:Blotting, Western / Q000662:veterinary; D002454:Cell Differentiation / Q000276:immunology*; D017931:DNA Primers / Q000235:genetics; D005434:Flow Cytometry / Q000379:methods / Q000662:veterinary*; D008070:Lipopolysaccharides; D008213:Lymphocyte Activation / Q000276:immunology*; D008969:Molecular Sequence Data; D017686:Oncorhynchus mykiss / Q000276:immunology*; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000662:veterinary; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D017931:DNA Primers; D008070:Lipopolysaccharides; D014157:Transcription Factors