IgM is present on the surface of B lymphocytes in monomeric form and can also be secreted into the serum in pentameric form after differentiation of B cells into plasma cells. We have previously used a monoclonal population of murine tumor cells (BCL1) which express surface IgM but can also secrete IgM after stimulation with lipopolysaccharide to study the primary structure of μ chains from cell surface and secreted IgM. Using cation exchange chromatography, we detected a peptide present only in μ chains from secreted IgM but not in cell surface IgM. The putative extra peptide(s) from the cell surface μ chain could not be identified perhaps due to its inability to bind to the exchange resin. In the present study we have used reverse phase high pressure liquid chromatography to analyse the peptides of μ chains from cell surface and secreted IgM from both BCL1 tumor cells and from normal B lymphocytes. Our results demonstrate the presence of two peptides associated with the Fc portion of the cell surface but not with the secreted μ chain.
ASJC Scopus subject areas
- Molecular Biology