B-1-like cells exist in sheep. Characterization of their phenotype and behaviour.
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.
Chevallier
N
N
URA INRA-ENVA d'Immunopathologie Cellulaire et Moléculaire, Maisons-Alfort cedex, France.
Berthelemy
M
M
Lainé
V
V
Le Rhun
D
D
Féménia
F
F
Polack
B
B
Naessens
J
J
Levy
D
D
Schwartz-Cornil
I
I
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
D018956:CD5 Antigens; D007075:Immunoglobulin M; D016167:Integrin alphaXbeta2; D016177:Macrophage-1 Antigen; D017464:Receptors, Complement 3d; D011971:Receptors, Immunologic