Structural studies of cell surface and secreted IgG in LPS-stimulated murine B cells

We have characterized the cell surface IgG of LPS-stimulated B lymphocytes by surface iodination and specific immunoprecipitation. IgG3 was found to be the predominant IgG subclass expressed on the B cell surface after 5 days of stimulation with LPS. In contrast, IgG2b, IgG3, and IgG1 subclasses are all secreted. Cell surface IgG exhibits detergent binding characteristics not shown by secreted IgG and the gamma chains of the three subclasses of surface IgG examined have the apparent mol. wt of 64 Kd, some 9,000 larger than the H chains of secreted IgG.