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Canine non-B, non-T NK lymphocytes have a potential antibody-dependent cellular cytotoxicity function against antibody-coated tumor cells.

ABSTRACT: BACKGROUND:The antibody-dependent cellular cytotoxicity (ADCC) is a cell-mediated immune defense mechanism in which effector immune cells actively lyse antibody-coated target cells. The ADCC of tumor cells is employed in the treatment of various cancers overexpressing unique antigens, and only natural killer (NK) cells are known to be major effectors of antibody mediated ADCC activity. Canine NK cells are still defined as non-B, non-T large granular lymphocytes because of the lack of information regarding the NK cell-restricted specific marker in dogs, and it has never been demonstrated that canine NK cells have ADCC ability against tumor cells. In the present study, we investigated whether canine non-B, non-T NK cells have ADCC ability against target antibody-coated tumor cells, using cetuximab and trastuzumab, the only human antibodies reported binding to canine cancer cells. RESULTS:Activated canine non-B, non-T NK cells (CD3-CD21-CD5-TCRαβ-TCRγδ-) for 13~17 days ex vivo showed ADCC ability against trastuzumab- or cetuximab-coated target tumor cells expressing various levels of human epidermal growth factor receptor 2 (HER-2) and epidermal growth factor receptor (EGFR). Trastuzumab and cetuximab induced significant ADCC responses of canine NK cells even in CMT-U334 and CF41.Mg cells expressing low levels of HER-2 and/or EGFR, as well as in SKBR3 and DU145 cells overexpressing HER-2 and/or EGFR. The trastuzumab-mediated ADCC activity of NK cells was significantly enhanced by treatment with rcIL-21. CONCLUSIONS:The results of this study suggest that canine non-B, non-T NK lymphocytes have a potential ADCC function and that combinational strategies of monoclonal antibodies with either cytokines, which activate NK cells in vivo, or adoptive transfer of NK cells may be a feasible method for amplifying the efficacy of immunotherapy against malignant cancers even with very low expression of target molecules in dogs.

SUBMITTER: Kim Y

PROVIDER: S-EPMC6790994 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Although programmed cell death-1/programmed death-ligand 1 (PD-L1) inhibitors show remarkable antitumor activity, a large portion of patients with cancer, even those with high PD-L1-expressing tumors, do not respond to their effects. Most PD-L1 inhibitors contain modified fragment crystallizable region (Fc) receptor binding sites to prevent antibody-dependent cellular cytotoxicity (ADCC) against PD-L1-expressing non-tumor cells. However, natural killer (NK) cells have specific antitumor activity in the presence of tumor-targeting antibody through ADCC, which could enhance NK cell-induced cytotoxicity. We evaluated the antitumor efficacy of ADCC via anti-PD-L1 monoclonal antibodies (mAbs) and NK cells against several PD-L1-positive cancer cell lines. Various cancer cell lines were used as target cell lines. Surface PD-L1 expression was analyzed by flow cytometry. IMC-001 and anti-hPD-L1-hIgG1 were tested as anti-PD-L1 mAbs with ADCC and atezolizumab as an anti-PD-L1 mAb without ADCC. NK cell cytotoxicity was measured by 51Cr-release assay and CD107a degranulation assay. Also, live cell imaging was performed to evaluate cytotoxicity in a single-cell level. NK-92-CD16 (CD16-transduced NK-92 cell line) and peripheral blood mononuclear cells from healthy donors, respectively, were used as an effector cell. FcγRIIIa (CD16a)-V158F genotyping was performed for healthy donors. We demonstrated that the cytotoxicity of NK-92-CD16 cells toward PD-L1-positive cancer cell lines was significantly enhanced in the presence of anti-PD-L1 mAb with ADCC. We also noted a significant increase in primary human NK cell cytotoxicity against PD-L1-positive human cancer cells when cocultured with anti-PD-L1 mAb with ADCC. Moreover, NK cells expressing a FCGR3A high-affinity genotype displayed higher anti-PD-L1 mAb-mediated ADCC lysis of tumor cells than donors with a low-affinity genotype. These results suggest that NK cells induce an ADCC response in combination with anti-PD-L1 mAbs, which helps promote ADCC antitumor activity against PD-L1-positive tumors. This study provides support for NK cell immunotherapy against high PD-L1-expressing tumors in combination with ADCC through anti-PD-L1 mAbs.

Project description:Lifelong antiretroviral therapy (ART) for HIV-1 does not diminish the established latent reservoir. A possible cure approach is to reactivate the quiescent genome from latency and utilize immune responses to eliminate cells harboring reactivated HIV-1. It is not known whether antibodies within HIV-1-infected individuals can recognize and eliminate cells reactivated from latency through antibody-dependent cellular cytotoxicity (ADCC). We found that reactivation of HIV-1 expression in the latently infected ACH-2 cell line elicited antibody-mediated NK cell activation but did not result in antibody-mediated killing. The lack of CD4 expression on these HIV-1 envelope (Env)-expressing cells likely resulted in poor recognition of CD4-induced antibody epitopes on Env. To examine this further, cultured primary CD4(+) T cells from HIV-1(+) subjects were used as targets for ADCC. These ex vivo-expanded primary cells were modestly susceptible to ADCC mediated by autologous or heterologous HIV-1(+) serum antibodies. Importantly, ADCC mediated against these primary cells could be enhanced following incubation with a CD4-mimetic compound (JP-III-48) that exposes CD4-induced antibody epitopes on Env. Our studies suggest that with sufficient reactivation and expression of appropriate Env epitopes, primary HIV-1-infected cells can be targets for ADCC mediated by autologous serum antibodies and innate effector cells. The results of this study suggest that further investigation into the potential of ADCC to eliminate reactivated latently infected cells is warranted.An HIV-1 cure remains elusive due to the persistence of long-lived latently infected cells. An HIV-1 cure strategy, termed "shock and kill," aims to reactivate HIV-1 expression in latently infected cells and subsequently eliminate the reactivated cells through immune-mediated killing. While recent research efforts have focused on reversing HIV-1 latency, it remains unclear whether preexisting immune responses within HIV-1(+) individuals can efficiently eliminate the reactivated cells. HIV-1-specific antibodies can potentially eliminate cells reactivated from latency via Fc effector functions by recruiting innate immune cells. Our study highlights the potential role that antibody-dependent cellular cytotoxicity might play in antilatency cure approaches.

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Canine non-B, non-T NK lymphocytes have a potential antibody-dependent cellular cytotoxicity function against antibody-coated tumor cells.

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