siRNA silencing of PD-L1 and PD-L2 on dendritic cells augments expansion and function of minor histocompatibility antigen-specific CD8+ T cells.

Abstract

Tumor relapse after human leukocyte antigen-matched allogeneic stem cell transplantation (SCT) remains a serious problem, despite the long-term presence of minor histocompatibility antigen (MiHA)-specific memory T cells. Dendritic cell (DC)-based vaccination boosting MiHA-specific T-cell immunity is an appealing strategy to prevent or counteract tumor recurrence, but improvement is necessary to increase the clinical benefit. Here, we investigated whether knockdown of programmed death ligand 1 (PD-L1) and PD-L2 on monocyte-derived DCs results in improved T-cell activation. Electroporation of single siRNA sequences into immature DCs resulted in efficient, specific, and long-lasting knockdown of PD-L1 and PD-L2 expression. PD-L knockdown DCs strongly augmented interferon-γ and interleukin-2 production by stimulated T cells in an allogeneic mixed lymphocyte reaction, whereas no effect was observed on T-cell proliferation. Moreover, we demonstrated that PD-L gene silencing, especially combined PD-L1 and PD-L2 knockdown, resulted in improved proliferation and cytokine production of keyhole limpet hemocyanin-specific CD4(+) T cells. Most importantly, PD-L knockdown DCs showed superior potential to expand MiHA-specific CD8(+) effector and memory T cells from leukemia patients early after donor lymphocyte infusion and later during relapse. These data demonstrate that PD-L siRNA electroporated DCs are highly effective in enhancing T-cell proliferation and cytokine production, and are therefore attractive cells for improving the efficacy of DC vaccines in cancer patients.

• Authors: Willemijn Hobo, Frans Maas, Niken Adisty, Theo de Witte, Nicolaas Schaap, Robbert van der Voort, Harry Dolstra
• Journal: Blood (Blood) Vol. 116 Issue 22 Pg. 4501-11 (Nov 25 2010) ISSN: 1528-0020 [Electronic] United States
• PMID: 20682852 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Antigens, CD
• B7-H1 Antigen
• CD274 protein, human
• Cytokines
• Intercellular Signaling Peptides and Proteins
• Minor Histocompatibility Antigens
• PDCD1LG2 protein, human
• Programmed Cell Death 1 Ligand 2 Protein

Topics

• Antigens, CD (genetics, immunology)
• B7-H1 Antigen
• CD8-Positive T-Lymphocytes (cytology, immunology)
• Cell Proliferation
• Cells, Cultured
• Cytokines (immunology)
• Dendritic Cells (immunology, metabolism)
• Gene Silencing
• Humans
• Intercellular Signaling Peptides and Proteins (genetics, immunology)
• Minor Histocompatibility Antigens (immunology)
• Programmed Cell Death 1 Ligand 2 Protein