B-1A AND CONVENTIONAL B-CELLS FROM AUTOIMMUNE NZB.H-2BM12 MICE EXHIBIT SIMILAR FUNCTIONAL-CHARACTERISTICS IN-VIVO

NZB.H-2bm12 mice develop an autoimmune syndrome characterized by the o verproduction of anti-DNA antibodies and the expansion of B-1B cells. Thus, these animals provide a useful model to examine the antigenic sp ecificity, cross-reactivity and functional capability of B-1 versus co nventional lymphocytes. Neither the repertoire expressed by in vivo ac tivated Ly-1+ splenic lymphocytes, nor their cross-reactivity, differe d significantly from that of conventional splenic B cells. When Ly-1cells were cultured in vitro in the presence of lipopolysaccharide plu s interleukin-4 or interferon gamma, they underwent isotype switching at the same frequency as conventional B cells. Of interest, B-1 cells from the peritoneal cavity were significantly less likely to undergo i sotype switching than those from the spleen. These findings indicate t hat in vivo activated B-1a and conventional B cells from mice with lup us manifest similar functional characteristics.