Cell surface immunoglobulin. XXII. Reappearance of surface IgM and IgD on murine splenocytes after removal by capping

The binding of polyvalent antigens or divalent anti-Ig antibody to antigen-specific receptors on B lymphocytes results in capping followed by shedding or endocytosis of the complexes. After the loss of surface Ig, adult lymphocytes reexpress their receptors, whereas neonatal cells appear to be permanently modulated. Splenocytes from neonatal mice bear only IgM, whereas the vast majority of adult B cells express both IgM and IgD. It is not known whether IgD and IgM on adult splenocytes are reexpressed at the same rate after capping. To investigate this question, we removed both IgM and IgD from splenocytes of adult mice and examined the reappearance of both isotypes at intervals after cell culture. The results demonstrate that both isotypes reappear on the cell surface at a similar rate.