Targeting human B-cell malignancies through Ig light chain-specific cytotoxic T lymphocytes

Area of Science:

• Immunology
• Oncology
• Vaccinology

Background:

• Malignant B cells express unique idiotype (Id) proteins, serving as tumor-specific antigens.
• Id-derived epitopes can elicit humoral and cellular immunity against B-cell tumors.
• Characterization of Id epitopes stimulating human CD8(+) T-cell immunity is incomplete.

Purpose of the Study:

• To identify and characterize novel idiotypic (Id) epitopes that stimulate human CD8(+) T-cell immunity.
• To evaluate the potential of these epitopes for B-cell malignancy vaccines and T-cell therapies.

Main Methods:

• Sequencing of immunoglobulin V(L) regions from myeloma cell line U266 and primary B-cell tumors.
• Testing of V(L) peptides for their ability to stimulate cytotoxic T-lymphocytes (CTLs) from HLA-A*0201-positive donors.
• Assessment of CTL activity against peptide-pulsed T2 cells and autologous tumor cells.

Main Results:

• Generated 68 CTL lines recognizing 14 distinct V(L) peptides from U266 and B-cell tumors.
• CTLs produced IFN-γ and lysed peptide-pulsed T2 cells and autologous tumor targets in an HLA class I-dependent manner.
• Identified shared V(L) T-cell epitopes, distinct from previously reported V(H) epitopes.

Conclusions:

• Novel immunogenic CTL epitopes derived from idiotype (Id) light chain (V(L)) have been identified.
• These epitopes are naturally presented on B-cell malignancies, supporting their use in next-generation Id vaccines.
• The findings support strategies for generating allogeneic tumor-specific T cells for adoptive transfer.