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 overproduction of anti-DNA antibodies and the expansion of B-1 B cells. Thus, these animals provide a useful model to examine the antigenic specificity, cross-reactivity and functional capability of B-1 versus conventional lymphocytes. Neither the repertoire expressed by in vivo activated Ly-1+ splenic lymphocytes, nor their cross-reactivity, differed significantly from that of conventional splenic B cells. When Ly-1+ cells were cultured in vitro in the presence of lipopolysaccharide plus 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 isotype switching than those from the spleen. These findings indicate that in vivo activated B-1a and conventional B cells from mice with lupus manifest similar functional characteristics.