Transient expression of pentameric IgM on the surface of NZB B cells.

In contrast to normal B lymphocytes, splenic B cells from autoimmune NZB mice express on their surface greater amounts of IgM than IgD. We have found that the predominant mu chain species present on these cells is derived from pentameric secretory IgM which can be radioiodinated during transient association with the cell membrane. If the contribution from 19S IgM is discounted, then the surface IgM:IgD ratio of NZB mice is only moderately higher than that of B cells from normal strains.