RAPID COMMUNICATION Specific Binding of Leukemia Oncogene Fusion Protein Peptides to HLA

Many human leukemias are characterized by chromosomal translocations yielding hybrid RNAs capable of encoding fusion chimeric proteins. The unique amino acid sequences found in these oncogenic fusion proteins represent true tumor-speclfc antigens that are potentially immunogenic. Although these leukemia-specific fusion proteins have an intracellular location, they might be r cognized immunologically by T lymphocytes if peptides derived from the unique sequences are capable of presentation by the major histocompatibility complex (MHC) molecules on leukemic cells. The ability of a series of synthetic peptides corresponding to the junctional sequences of chronic myelogenous leukemia (CMLkderived bcr-ab1 and acute promyelocytic leukemia (APLI-derived PML-RARa fusion proteins to bind to purified class I molecules was studied, A series of 152 peptides 8,9, 10, and 11 amino acids in length, spanning the b3a2 and