Increased serum IgG1 levels and reduced numbers of B-1 B cells in DBA/2J mice.

B-cell heterogeneity studies have historically focused upon BALB/c mice and their derivatives. In contrast, the B cells of DBA/2J mice, a prototype strain for the study of the endogenous minor lymphocyte stimulatory (Mls) viral superantigen Mls-1a, have not been extensively investigated. DBA/2J B cells, by functioning as Mls-1a antigen-presenting cells, influence their own differentiation and diversity by inducing the proliferation and differentiation of specific CD4 T-cell subsets. In this report, the B cells of DBA/2J and BALB/c mice were compared for their ability to restore B-cell function in severe combined immunodeficient (SCID) recipients. Although spleen and bone marrow cells from these strains exhibited similar restoration of serum IgM production, the transfer of DBA/2J B cells into SCID mice led to greater IgG1 production. The peritoneal cells of DBA/2J mice consisted of a lower percentage of B-1 B cells and were less capable of restoring B-cell function after transfer into SCID recipients. These differences are discussed with respect to the possible role of viral superantigens in influencing B-lymphocyte diversity.