Production of immunoglobulin isotypes by Ly-1+ B cells in viable motheaten and normal mice.

Almost all B cells in autoimmune mice with the viable motheaten (mev) mutation express the Ly-1 cell surface antigen, which marks a minor population of B cells constituting a separate lineage in normal mice. Immunoglobulins primarily of the M and G3 classes, which in both normal and mev mice contain high levels of lambda light chain, are produced in excess in mev mice. These and other observations suggest that the development of B cells that express Ly-1 is regulated independently from the development of B cells that do not express Ly-1. B cells bearing the Ly-1 surface antigen may play specialized roles in the normal immune system and in autoimmunity by regulating other B cells via lymphokines, by producing antibodies to self and certain foreign antigens, and by preferentially secreting immunoglobulin M and immunoglobulin G3.