Newly identified human epsilon immunoglobulin peptides and related products

The invention includes human epsilon chain transmembrane anchor peptide resulting from mRNA splicing other than the C epsilon 4 exon, the epsilon m1 exon, and the epsilon m2 exon. Two new peptides in particular have been specifically identified. These novel peptides are not present in the conventional secreted (and circulating) IgE. These peptides provide antigenic sites for antibody binding. Thus, the invention further includes antibodies to such peptide segments, as well as such antibodies conjugated to cytotoxic agents, and their use in extracorporeal or in vivo therapy.