Immunoglobulin light chain, Blimp-1 and cytochrome P4501B1 peptides as potential vaccines for AL amyloidosis.

Amyloid light chain (AL) amyloidosis is a lethal disorder characterized by the pathologic deposition of clonal plasma cell-derived, fibrillogenic immunoglobulin light chains in vital organs. Current chemotherapeutic regimens are problematic in patients with compromised organ function and are not effective for all patients. Here, a platform of computer-based prediction and preclinical mouse modeling was used to begin development of a complementary, immunotherapeutic approach for AL amyloidosis. Three peptide/MHC I-binding algorithms identified immunogenic peptides from three AL plasma cell-associated proteins: (1) amyloidogenic λ6 light chains, (2) CYP1B1, a universal tumor antigen hyper-expressed in AL plasma cells and (3) B lymphocyte-induced maturation protein 1 (Blimp-1), a transcription factor required for plasma cell differentiation. The algorithms correctly predicted HLA-A(*)0201-binding native and heteroclitic peptides. In HLA-A2 transgenic mice, these peptides, given individually or in combination, induced potent CTL which kill peptide-loaded human lymphoma cells and/or lymphoma cells producing target protein. Blimp-1 peptide-immunized mice exhibited a reduced percentage of splenic, lymph node and bone marrow plasma cells and a decrease in the absolute number of splenic plasma cells demonstrating (1) presentation of target peptide by endogenous plasma cells and (2) appropriate CTL homing to lymphoid organs followed by killing of target plasma cells. These studies suggest that AL amyloidosis, with its relatively low tumor cell burden, may be an attractive target for peptide-based multivalent vaccines.