Antibodies specific for isotype specific domains of human IgM and human IgG expressed or the B cell surface

Membrane anchoring peptides are attached to the C terminal end of the heavy chain of the various immunoglobulin isotypes (IgM, IgD, IgA, IgE, or IgG). The membrane anchoring peptides span the cell membrane lipid bilayer of B cells thereby affixing the associated immunoglobulin to the cell membrane surface. The extracellular segments of these peptides are unique for different isotypes. Epitopes unique to the B cells which produce each isotype are formed, in whole or in part, by these extracellular segments. These membrane-bound immunoglobulin isotype-specific ("migis") extracellular epitopes are not present on the secreted, soluble form of the immunoglobulins, which are not bound to the cell surface by the membrane anchoring peptides. The antibodies of the invention (and other related products) specifically bind to the extracellular migis epitopes of human (my) chain, human (delta) chain, or human (gamma) chain. The B cells which express the isotypes IgM, IgD or IgG are labeled for destruction when bound by such antibodies or products, and can be destroyed by the cytolytic or regulatory mechanisms of the immune system in order to cause immunosuppression.