Combining dendritic cells and B cells for presentation of oxidised tumour antigens to CD8⁺ T cells

Abstract

The dendritic cell (DC) is the foremost antigen-presenting cell (APC) for ex vivo expansion of tumour-specific patient T cells. Despite marked responses in some patients following reinfusion of DC-activated autologous or HLA-matched donor T cells, overall response rates remain modest in solid tumours. Furthermore, most studies aim to generate immune responses against defined tumour-associated antigens (TAA), however, meta-analysis reveals that those approaches have less clinical success than those using whole tumour cells or their components. Tumour lysate (TL) is used as a source of tumour antigen in clinical trials and potentially represents the full range of TAAs in an undefined state. Little is known about how different APCs cooperate to present TL antigens. We examined the effect of oxidised whole-cell lysate (ox-L) versus soluble fraction freeze–thaw lysate (s-L) on bone marrow-derived DCs and macrophages, and magnetic bead-isolated splenic B cells. The APCs were used individually, or in combination, to prime T cells. CD8+ T cells produced interferon (IFN)-γ in response to both s-L and ox-L, but only proliferated in response to ox-L. IFN-γ production and proliferation was enhanced by priming with the DC+B cell combination. Compared to DC alone, a trend toward greater interleukin (IL)-12 production was observed when DC+B cell were loaded with s-L and ox-L antigens. CD8+ T-cell specific lysis in vivo was greatest in ox-L-primed groups and DC+B cell priming significantly increased in vivo cytotoxicity compared to DC alone. These improved T-cell responses with two APCs and stressed cell lysate has implications for APC-based adoptive cell therapies.

Tumor cell lysate-loaded immunostimulatory spherical nucleic acids as therapeutics for triple-negative breast cancer

“…Furthermore, generating lysates from cells that have been subjected to oxidative stress with HOCl to induce cell death results in protein populations of higher molecular weight than those isolated from cells that have not been subjected to oxidative stress. This finding confirms that cellular oxidation prior to lysate generation changes the available antigen pool, which is in agreement with published studies on the use of oxidized lysates in DC vaccines (20,68). When incubated with BMDCs in vitro, oxidized lysates enhance DC maturation over both nonoxidized lysates and CpG-1826.…”

“…However, direct vaccination using tumor lysates has been met with limited success, due to low cellular uptake and bioavailability after injection, resulting in minimal immunogenicity (19). Oxidizing tumor cells prior to lysate isolation and preparation significantly increases immunogenicity when the lysates are utilized as the antigen source in DC vaccines (19)(20)(21). Importantly, protein chlorination by hypochlorous acid (HOCl), an oxidant produced by neutrophils as part of the adaptive immune response, increases the immunogenicity of antigens severalfold (22), potentially due to their increased proteolytic susceptibility (23).…”

Impact of Liposomal Spherical Nucleic Acid Structure on Immunotherapeutic Function

“…Oxidizing cancer cells prior to lysate generation often increases their immunogenicity, − and incorporating oxidized lysates into the core of L-SNAs leads to dramatic increases in the antitumor efficacy in mouse models of TNBC . Therefore, to determine whether the effects of tumor cell oxidation and L-SNA stability were additive, L-SNAs containing lysates from oxidized Py8119 cells were synthesized using DOPC (DOPC-OxLys-SNAs) and DPPC (DPPC-OxLys-SNAs).…”

Activation of Cellular Players in Adaptive Immunity via Exogenous Delivery of Tumor Cell Lysates

“…The oxidation of source tumor cells prior to the preparation of TCLs could facilitate necrosis and augment the immunogenicity of the antigenic components in TCLs by increasing oxidative stress ( Figure 2 E). Through this modulation, DCs could boost the uptake of antigenic danger signals and antigen processing mechanisms [ 44 ]. Therefore, hypochlorous acid (HOCl)-mediated oxidation is used for the generation of effective TCL contents, since protein chlorination enhances proteolytic vulnerability and improves the immunogenicity of the antigenic components [ 45 ].…”