Identification of a Decapeptide Region of Human Interferon-α with Antiproliferative Activity and Homology to an Immunosuppressive Sequence of the Retroviral Transmembrane Protein P15E

We have identified a 10-amino acid sequence (amino acid, 9–18) from interferon-α (IFN-α) that when presented as a synthetic peptide inhibits both the proliferation of the Daudi lymphoblastoid cell line and the antigen receptor-stimulated proliferation of fresh human T lymphocytes. This sequence, which was identified by virtue of its sequence similarity (70% identity) to the immunosuppressive sequence of the retroviral transmembrane protein pl5E, represents the smallest fragment of IFN-α that has been shown to date to be biologically active.