Injection of mice with polyclonal goat anti-mouse IgD antibody (G alpha M delta) stimulates a potent T cell-dependent immune response characterized by large increases in serum IgG1 and IgE concentrations and by the generation of substantial numbers of membrane (m)IgG1+ B cells. The onset of this response occurs 6 days after G alpha M delta injection and peaks by day 7 to 8. Utilizing two color fluorescence analysis and cell sorting we demonstrate that most mIgG1-expressing B cells lack mIgM during the period of onset of Ig isotype switching (day 6). Both IgG1 and IgE are produced predominantly by mIgM- cells. On day 6, IgG1 and IgE are secreted predominantly by cells expressing mIgG1 and mIgE, respectively. By day 8, a majority of the IgG1 secretion occurs among the mIgG1- cells but virtually all IgE secretion continues to come from the mIgE+ population. B cells that strongly express mIgG1 secrete little IgM or IgE. Freshly harvested B cells expressing mIgG1, 6 days after G alpha M delta injection, have undergone substantial deletion of CH mu-specific DNA in contrast to their mIgG1- counterparts. Hence, the great majority of B cells that switch to the IgG1 or IgE isotypes in vivo rapidly lose their expression of IgM.

This content is only available via PDF.
You do not currently have access to this content.