Targeting CLEC9A delivers antigen to human CD141+ DC for CD4+ and CD8+T cell recognition
Kirsteen M. Tullett ... Mireille H. Lahoud, Kristen J. Radford
Kirsteen M. Tullett ... Mireille H. Lahoud, Kristen J. Radford
Published May 19, 2016
Citation Information: JCI Insight. 2016;1(7):e87102. doi:10.1172/jci.insight.87102.
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Categories: Technical Advance Immunology Vaccines

Targeting CLEC9A delivers antigen to human CD141+ DC for CD4+ and CD8+T cell recognition

Abstract

DC-based vaccines that initiate T cell responses are well tolerated and have demonstrated efficacy for tumor immunotherapy, with the potential to be combined with other therapies. Targeting vaccine antigens (Ag) directly to the DCs in vivo is more effective than cell-based therapies in mouse models and is therefore a promising strategy to translate to humans. The human CD141+ DCs are considered the most clinically relevant for initiating CD8+ T cell responses critical for killing tumors or infected cells, and they specifically express the C-type lectin-like receptor CLEC9A that facilitates presentation of Ag by these DCs. We have therefore developed a human chimeric Ab that specifically targets CLEC9A on CD141+ DCs in vitro and in vivo. These human chimeric Abs are highly effective at delivering Ag to DCs for recognition by both CD4+ and CD8+ T cells. Given the importance of these cellular responses for antitumor or antiviral immunity, and the superior specificity of anti-CLEC9A Abs for this DC subset, this approach warrants further development for vaccines.

Authors

Kirsteen M. Tullett, Ingrid M. Leal Rojas, Yoshihito Minoda, Peck S. Tan, Jian-Guo Zhang, Corey Smith, Rajiv Khanna, Ken Shortman, Irina Caminschi, Mireille H. Lahoud, Kristen J. Radford

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Generation, internalization, and accumulation of human chimeric Ab-pp65 ...

Figure 1

Generation, internalization, and accumulation of human chimeric Ab-pp65 fusion proteins.

(A) Diagram of human chimeric mAb, consisting of rat or mouse variable regions joined to human IgG4 and κ constant regions, genetically fused to the CMV pp65 antigen (Ag) and FLAG tag via linker sequences. (B) Binding of human chimeric Ab to human PBMCs was assessed by incubating PBMCs with anti-CLEC9A Ab (black, left panel), anti–DEC-205 Ab (black, right panel), or isotype Ab (gray), detected with anti–human IgG4-biotin and streptavidin-PE and analyzed by flow cytometry. Data are representative of 2 independent experiments. (C) DCs were incubated with human chimeric Ab at 4°C for 30 minutes and subsequently incubated at 4°C or 37°C. DCs were stained with anti–human IgG-biotin and streptavidin-PE at indicated time points to label remaining surface-bound Ab and analyzed by flow cytometry. Data shown are the mean fluorescence intensity (MFI) and are representative of 3 independent experiments from different donors. (D) Accumulation of human chimeric Ab by human DCs enriched from PBMCs. Alexa Fluor 488–labeled (AF 488–labeled) human chimeric Abs were cultured with DCs at 37°C for up to 12 hours in the presence or absence of poly I:C or R848. Cells were counterstained for HLA-DR, live/dead aqua, CD141, and CD1c and analyzed by flow cytometry. Data show the MFI, which was normalized for conjugation efficiency of the human chimeric Ab, and are the mean ± SD of 3 donors.