B-1a and conventional B cells from autoimmune NZB. H-2bm12 mice exhibit similar functional characteristics in vivo

NZB. H-2^bm12 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-l 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 lipopolysac-charide plus interleukin-4 or interferon γ, they underwent isotype switching at the same frequency as conventional B cells. Of interest, B-l 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-l^a and conventional B cells from mice with lupus manifest similar functional characteristics.