DBA/2J (Mls-1a) B-cell differentiation in BALB.xid recipients

Studies of superantigens (SAg) have focused primarily on their impact on CD4+ T cells, largely bypassing the impact of the sequelae of this interaction upon the antigen-presenting cell (APC). Sequelae of SAg-induced CD4+ T-cell activation include the 'bathing' of the SAg-presenting cell with cytokines that promote the differentiation of the APC. In this report, the SAg-induced differentiation of Mls+ DBA/2J B cells was studied in vivo by their transplantation into B-cell-defective BALB.xid recipients. Rapid, high-level serum immunoglobulin M (IgM) production was noted shortly after transfer, disappearing by 3 weeks. Donor B cells, as evidenced after their chemical and genetic impairment and by the use of an IgM allotype-disparate donor-recipient combination, contributed to this transient IgM production. These results clarify a discrepancy in the literature regarding donor B-cell contribution to IgM production and illustrate a model system to utilize SAg to study B-lymphocyte diversity.