OBJECTIVETo test the antitumor effect of a human triple-negative breast cancer cell-dendritic cell (DC) fusion vaccine.

METHODSDCs were isolated from fresh peripheral blood of healthy donors. The fusion vaccine was prepared by fusing the DCs and MDA-MB-231 cells via electrofusion. The morphology of the vaccine was identified under inverted fluorescence microscope and the phenotypes were analyzed with flow cytometry. The production of interleukin-12 (IL-12) and interferon-γ (IFN-γ) by the fusion cells was assessed using ELISA. A CCK-8 kit was used to examine the effect of the vaccine in stimulating the proliferation and cytotoxicity of autologous T lymphocytes.

RESULTSThe DCs isolated from peripheral blood mononuclear cells highly expressed CD83, CD86, CD11c and HLA-DR on the cell surface. The fusion cells were irregular in shape and coexpressed the phenotypes of DCs and MDA-MB-231 cells. The fusion cells possessed a strong ability to stimulate the proliferation of T lymphocytes in vitro. Compared with the control group, the fusion vaccine showed a stronger antitumor effect against the breast cancer cells.

CONCLUSIONThe triple-negative breast cancer-DC fusion vaccine prepared by electrofusion can stimulate the proliferation of T lymphocytes and induces strong cytotoxicity of the T cells against breast cancer cells.

Breast Neoplasms ; immunology ; Cancer Vaccines ; immunology ; Cell Fusion ; Cell Line, Tumor ; Dendritic Cells ; immunology ; Female ; Humans ; Interferon-gamma ; immunology ; Interleukin-12 ; immunology ; Lymphocyte Activation ; T-Lymphocytes, Cytotoxic ; immunology

New threats posed by the emerging circulating variants of SARS-CoV-2 highlight the need to find conserved neutralizing epitopes for therapeutic antibodies and efficient vaccine design. Here, we identified a receptor-binding domain (RBD)-binding antibody, XG014, which potently neutralizes β-coronavirus lineage B (β-CoV-B), including SARS-CoV-2, its circulating variants, SARS-CoV and bat SARSr-CoV WIV1. Interestingly, antibody family members competing with XG014 binding show reduced levels of cross-reactivity and induce antibody-dependent SARS-CoV-2 spike (S) protein-mediated cell-cell fusion, suggesting a unique mode of recognition by XG014. Structural analyses reveal that XG014 recognizes a conserved epitope outside the ACE2 binding site and completely locks RBD in the non-functional "down" conformation, while its family member XG005 directly competes with ACE2 binding and position the RBD "up". Single administration of XG014 is effective in protection against and therapy of SARS-CoV-2 infection in vivo. Our findings suggest the potential to develop XG014 as pan-β-CoV-B therapeutics and the importance of the XG014 conserved antigenic epitope for designing broadly protective vaccines against β-CoV-B and newly emerging SARS-CoV-2 variants of concern.
Angiotensin-Converting Enzyme 2 ; Antibodies, Neutralizing ; Antibodies, Viral ; COVID-19 ; Epitopes ; Humans ; SARS-CoV-2/genetics* ; Spike Glycoprotein, Coronavirus/genetics*