The control of antibody diversity during IgM and IgG anti-sheep red cell responses in mice.

The isoelectric heterogeneity of both IgM and IgG murine anti-sheep red cell serum antibodies has been examined using an adaptation of published methods. It was found that the IgM spectra were restricted in a characteristic manner, implying oligoclonality. In cell transfer experiments, the T cell dependency of the IgM responses was confirmed. Further, helper cells appeared to switch on IgG antibody production and, simultaneously, recruit many novel IgG-forming clones into the response. The pattern of the IgM oligoclonality was attributed in part to the inheritance of genes at, or closely linked to, the Igl heavy chain locus. These findings are discussed in relation to current research on the regulation of diversity.