Identification of autoimmune thrombocytopenic purpura-related epitopes using phage-display peptide library

A random heptapeptide phage-displayed library was screened with two serum samples from autoimmune thrombocytopenic purpura (AITP) patients to address the repertoire of autoantigenic epitopes involved in platelet destruction. We obtained a panel of affinity-selected phage clones that have been shown to react in enzyme-linked immunosorbent assay with autoantibodies from other AITP patients. None of the peptides obtained has been described previously as possibly being an epitope for antiplatelet antibodies, and the majority of them did not show any homology with known platelet glycoproteins. We conclude that peptides identified in this study could represent discontinuous epitopes or mimotopes of natural autoantigens. Also, they could be present in still-unknown proteins involved in AITP pathogenesis.