Pr1 Is Cross-Presented By Multiple Myeloma Cells In Patients And Renders Multiple Myeloma Susceptible To Pr1-Ctl And Anti-Pr1/Hla-A2 Antibody

PR1 is an HLA-A2-retricted, nonameric peptide that is derived from the azurophil granule proteases neutrophil elastase (NE) and proteinase 3 (P3). PR1 has been targeted successfully in acute (AML) and chronic (CML) myeloid leukemia using anti-PR1/HLA-A2 antibody (8F4), PR1-peptide vaccine and PR1-specific cytotoxic T lymphocytes (PR1-CTL). We have previously reported that NE and P3 are cross-presented by normal B cells and dendritic cells (DC), leading to PR1 expression by HLA-A2. Since multiple myeloma (MM) is a B cell malignancy, we investigated whether MM cells can cross-present PR1 as a possible target for immunotherapy.