The level of expression of mu heavy chain modifies the composition of peripheral B cell subpopulations.
The B cell receptor (BCR) has a decisive role in transducing signals required for the development of B cells and their survival in the periphery. However, the processes that initiate these signals remain unclear and concepts of constitutive and ligand-dependent signaling have been proposed. Using a mu-transgenic mouse model, we have analyzed the impact of high surface IgM expression on the composition of the splenic B cell population. kappa-deficient mice homozygous for the H3-mu transgene have B cells with a higher BCR surface density than H3 heterozygous mice. This higher BCR expression is associated with an increase in the percentage and the total number of splenic B cells. In addition, an important proportion of CD23(-)CD21(+) marginal zone (MZ) B cells can be observed in H3 homozygous mice. However, these modifications operate in the absence of impairment of the positive selection process of the H3-mu/lambda1 combination over the H3-mu/lambda2 + 3 ones. These results suggest that (i) a constitutive BCR signaling directly correlated with BCR surface density is responsible for the efficient B cell colonization of the periphery with an accumulation of B cells in the MZ and (ii) a ligand-dependent BCR signal is responsible for the clonotype composition of the mature B cell repertoire.
Sanchez
P
P
Laboratoire d'Immunobiologie, Case 7048, Université Denis-Diderot (Paris 7), 2 Place Jussieu, 75251 Paris Cedex 05, France. Institut Jacques Monod, 75005 Paris, France.
Crain-Denoyelle
A M
AM
Daras
P
P
Gendron
M C
MC
Kanellopoulos-Langevin
C
C
D000818:Animals; D016175:B-Lymphocyte Subsets / Q000502:physiology*; D002454:Cell Differentiation; D007148:Immunoglobulin mu-Chains / Q000235:genetics / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D011947:Receptors, Antigen, B-Cell / Q000502:physiology; D017464:Receptors, Complement 3d / Q000032:analysis; D017455:Receptors, IgE / Q000032:analysis; D015398:Signal Transduction; D019076:Transgenes
D007148:Immunoglobulin mu-Chains; D011947:Receptors, Antigen, B-Cell; D017464:Receptors, Complement 3d; D017455:Receptors, IgE