title: B-1-like cells exist in sheep. Characterization of their phenotype and behaviour.
abstract: Two populations of B lymphocytes, B-1 (CD5+ and/or CD11b+) and B-2 (CD5- and CD11b-) cells have been described. In mice, which is the species of reference for B-1 and B-2 cell studies, these two subsets present different developmental schemes, phenotypes, antibody repertoires, localization and behaviours. Interestingly, in sheep, B cells rearrange their immunoglobulin (Ig) loci around the neonatal period, similarly to murine B-1 cells. However, the phenotype of the sheep B cells has not been characterized with regards to their developmental pathway. In this report, we show that two sheep B-cell subsets can be distinguished on the basis of CD11b expression. Relative to CD11b- B cells, the CD11b+ B cells frequently co-express CD5, CD11c, higher levels of surface IgM (sIgM), show larger cell size and higher cell-cycling activity, and thus present a B-1-like phenotype. However, unlike murine B-1 cells, sheep B-1 like cells mainly localize in blood, display a higher propensity to spontaneous apoptosis relative to B-2-like cells, and proliferate after sIgM stimulation. Our data show that despite neonatal immunoglobulin loci rearrangements, sheep B cells do not all express a B-1-like phenotype. However, B-1-and B-2-like cells co-exist and present phenotypic and behavioural specificities. Nevertheless, sheep B-1-and B-2-like cells differ from the murine B-1 and B-2 cells in their cell behaviour. These subsets can thus not be considered as true homologues among species.
authors.affiliation: URA INRA-ENVA d'Immunopathologie Cellulaire et Moléculaire, Maisons-Alfort cedex, France.
authors.forename: N
authors.initials: N
authors.lastname: Chevallier
authors.forename: M
authors.initials: M
authors.lastname: Berthelemy
authors.forename: V
authors.initials: V
authors.lastname: Lainé
authors.forename: D
authors.initials: D
authors.lastname: Le Rhun
authors.forename: F
authors.initials: F
authors.lastname: Féménia
authors.forename: B
authors.initials: B
authors.lastname: Polack
authors.forename: J
authors.initials: J
authors.lastname: Naessens
authors.forename: D
authors.initials: D
authors.lastname: Levy
authors.forename: I
authors.initials: I
authors.lastname: Schwartz-Cornil
mesh_terms: D000818:Animals; D017209:Apoptosis; D001402:B-Lymphocytes / Q000166:cytology / Q000276:immunology*; D018956:CD5 Antigens; D002453:Cell Cycle; D005260:Female; D015322:Gene Rearrangement, B-Lymphocyte; D007075:Immunoglobulin M / Q000276:immunology; D016130:Immunophenotyping; D016167:Integrin alphaXbeta2; D008213:Lymphocyte Activation / Q000502:physiology*; D016177:Macrophage-1 Antigen; D017464:Receptors, Complement 3d; D011971:Receptors, Immunologic / Q000378:metabolism; D012756:Sheep / Q000276:immunology*; D013045:Species Specificity
chemical_list: D018956:CD5 Antigens; D007075:Immunoglobulin M; D016167:Integrin alphaXbeta2; D016177:Macrophage-1 Antigen; D017464:Receptors, Complement 3d; D011971:Receptors, Immunologic