Synthetic Peptide Ligands of the Antigen Binding Receptor Induce Programmed Cell Death in a Human B-Cell Lymphoma

Peptide ligands for the antigen binding site of the surface immunoglobulin receptor of a human B-cell lymphoma cell line were identified with the use of filamentous phage libraries displaying random 8- and 12-amino acid peptides. Corresponding synthetic peptides bound specifically to the antigen binding site of this immunoglobulin receptor and blocked the binding of an anti-idiotype antibody. The ligands, when conjugated to form dimers or tetramers, induced cell death by apoptosis in vitro with an IC50between 40 and 200 nM. This effect was associated with specific stimulation of intracellular protein tyrosine phosphorylation.