Assessing vaccine potency using TCRmimic antibodies.
Dendritic cells (DCs) are highly specialized antigen-presenting cells of the immune system that are efficient at presenting peptide-antigen for the activation of T cells and are often the cell type of choice for vaccine targeting by virtue of high expression levels of MHC and costimulatory molecules. Since the level of peptide-MHC complex significantly influences stimulation of T cells, a proof-of-concept potency assay was developed to directly examine the presentation and density of MHC class I peptides derived from the processing of a model tumor antigen, (hCGbeta), on the surface of DCs. In this study we first generated antibodies (TCR mimics or TCRm) to two peptide-HLA-A*0201 epitopes derived from hCGbeta designated as TMT (40-48) and GVL (47-55). Characterization of each TCRm by ELISA and flow cytometric analysis, demonstrated specific binding to soluble recombinant HLA-A2 protein and HLA-A2.1+ T2 cells loaded with relevant peptide. TCRm reactive against the TMT and GVL epitopes blocked granzyme-B production by peptide-specific cytotoxic T lymphocytes (CTL) lines further supporting their recognition specificity. For the assessment of antigen presentation function, human immature monocyte-derived DCs (iDCs) were treated with the mannose receptor targeting vaccine, B11-hCGbeta and matured with Poly I:C. The TMT and GVL epitope reactive CTL lines responded to vaccine-treated but not vehicle-treated mature DCs (mDCs) with TMT and GVL TCRm specifically blocking IFN-gamma production. The TCRm were then used to directly confirm specific peptide-MHC complexes on mDCs. TCRm staining of vaccine-treated mDCs showed detection of the TMT and GVL peptide-HLA-A2 complexes. These findings demonstrate that TCRms may be important tools for determining the potency of DC-based vaccines.
Neethling
Francisca A
FA
Receptor Logic Ltd., Abilene, TX 79601, United States.
Ramakrishna
Venky
V
Keler
Tibor
T
Buchli
Rico
R
Woodburn
Tito
T
Weidanz
Jon A
JA
D000911:Antibodies, Monoclonal / Q000008:administration & dosage* / Q000276:immunology; D000918:Antibody Specificity; D000951:Antigens, Neoplasm / Q000276:immunology*; D019496:Cancer Vaccines / Q000008:administration & dosage* / Q000276:immunology; D002460:Cell Line; D003713:Dendritic Cells / Q000276:immunology; D000939:Epitopes / Q000276:immunology* / Q000378:metabolism; D015789:HLA-A2 Antigen / Q000235:genetics / Q000276:immunology*; D006801:Humans; D011948:Receptors, Antigen, T-Cell / Q000276:immunology*; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*
D000911:Antibodies, Monoclonal; D000951:Antigens, Neoplasm; D019496:Cancer Vaccines; D000939:Epitopes; D015789:HLA-A2 Antigen; D011948:Receptors, Antigen, T-Cell