Compartmentalization Of Lambda-Subtype Expression In The B-Cell Repertoire Of Mice With A Disrupted Or Normal C-Kappa Gene Segment

The establishment of the B cell repertoire depends on two major parameters. The first is determined by mechanistic processes that give rise to a great diversity of B cell receptors from a combination of multiple gene segments. The second is dominated by selective processes that recruit B cell clones via their Immunoglobulin receptors. To assess the impact of these parameters on the composition of B cell repertoire, we constructed a mouse model displaying a B cell repertoire limited in its diversity. To this end, we disrupted the C(kappa) segment by gene targeting. B cells from such mutant mice do not express the kappa light chain. Their light chain repertoire is therefore limited by the expression of only four main lambda light chains: lambda1, lambda2(V2), lambda2(Vx) and lambda3. In this study we described the proportions of each lambda subtype in various lymphoid compartments. Our results show that the lambda1 subtype is dominant in the spleen and the bone marrow. Moreover, lambda1 prevalence is independent of the wild or mutant C(kappa) genotype. These results suggest that the mechanistic processes are mainly responsible for the blas in lambda subtype expression. On the other hand, the lambda2(V2) and/or lambda3 subtypes are expressed at higher levels in the peritoneal cavity. Their prevalence is again observed regardless of the C(kappa) genotype and seems to be due to B1 cells. These results suggest that different mechanistic processes could control lambda subtype expression in B1 and B2 cell lineages.