Antitumor Monoclonal Antibodies Enhance Cross-Presentation of Cellular Antigens and the Generation of Myeloma-specific Killer T Cells by Dendritic Cells

The mechanism of antitumor effect of monoclonal antibodies (mAbs) is not fully understood. Here we show that coating myeloma cells with anti–syndecan-1 antibody promotes cross-presentation of cellular antigens by dendritic cells (DCs) to autologous T cells from healthy donors. The tumor cells treated with anti–syndecan-1 or isotype-matched control antibody were fed to HLA-mismatched monocyte-derived immature DCs. Tumor cell–loaded mature DCs induced a strong CD8+ T cell response that was specific for the cancer-testis (C-T) antigens expressed in the tumor. The CD8+ T cells killed peptide-pulsed targets, as well as myeloma tumor cells. Importantly, mAbs-coated tumor-loaded DCs were consistently superior to DCs loaded with peptides or dying cells for eliciting tumor-specific killer T cells. This enhanced cross-presentation was not due to enhanced tumor cell uptake or to DC maturation. When mixtures of NY-Eso-1-positive and -negative myeloma cells were captured by DCs, the anti–syndecan-1 antibody had to be on the NY-Eso-1-positive cells to elicit NY-Eso-1–specific response. Cross-presentation was inhibited by pretreatment of DCs with Fcγ receptor blocking antibodies. Targeting of mAb-coated tumors to DCs may contribute to the efficacy of tumor-reactive mAb and offers a new strategy for immunotherapy

Selective blockade of inhibitory Fcγ receptor enables human dendritic cell maturation with IL-12p70 production and immunity to antibody-coated tumor cells

he final differentiation or maturation of dendritic cells (DCs) in response to environmental stimuli influences their ability to both initiate immunity and determine the quality of the response to antigens. Circulating immune complexes and cell-bound immunoglobulins present in normal human sera represent a potential stimulus for inadvertent DC activation in the steady state and during autoimmunity. Here, we show that selective blockade of the inhibitory Fcγ receptor (FcγR) FcγRIIb with recently developed monoclonal antibodies leads to maturation of human monocyte-derived DCs, which depends on the presence of IgG in normal human plasma. Plasma, in the presence of an FcγRIIb blockade, caused the DCs to up-regulate the expression of costimulatory molecules and to produce the inflammatory mediator IL-12p70. FcγRIIb blockade of DCs loaded with tumor cells led to increased tumor-specific T cell immunity without the need for exogenous stimuli other than human plasma. Therefore, the activation status of DCs in the presence of normal human serum depends on the balance between activating and inhibitory FcγRs and can be enhanced by new antibodies that react selectively with FcγRIIb. These data suggest an approach for modifying this balance to enhance immunity to immune complexes and antibody-coated tumor cells and to silence DC activation by immune complexes in autoimmune states. © 2005 by The National Academy of Sciences of the USA

Antigen-specific inhibition of effector T cell function in humans after injection of immature dendritic cells

Immunostimulatory properties of dendritic cells (DCs) are linked to their maturation state. Injection of mature DCs rapidly enhances antigen-specific CD4+ and CD8+ T cell immunity in humans. Here we describe the immune response to a single injection of immature DCs pulsed with influenza matrix peptide (MP) and keyhole limpet hemocyanin (KLH) in two healthy subjects. In contrast to prior findings using mature DCs, rejection of immature DCs in both subjects led to the specific inhibition of MP-specific CD8+ T cell effector function in freshly isolated T cells and the appearance of MP-specific interleukin 10-producing cells. When pre-and postimmunization T cells were boosted in culture, there were greater numbers of MP-specific major histocompatibility complex tetramer-binding cells after immunization, but these had reduced interferon γ production and lacked killer activity. These data demonstrate the feasibility of antigen-specific inhibition of effector T cell function in vivo in humans and urge caution with the use of immature DCs when trying to enhance tumor microbial immunity

Rapid generation of broad T-cell immunity in humans after a single injection of mature dendritic cells

Dendritic cells (DCs) are potent antigen-presenting cells that initiate protective T-cell immunity in mice. To study the immunogenicity of DCs in humans, we injected 9 healthy subjects subcutaneously with a control injection of autologous monocyte-derived, mature DCs, followed 4-6 weeks later by DCs pulsed with keyhole limpet hemocyanin (KLH), HLA-A*0201- positive restricted influenza matrix peptide (MP), and tetanus toxoid (TT). Four more subjects received these antigens without DCs. Injection of unpulsed DCs, or antigens alone, failed to immunize. Priming of CD4+ T cells to KLH was observed in all 9 subjects injected with KLH-pulsed DCs, and boosting of TT-specific T-cell immunity was seen in 5 of 6 subjects injected with TT- pulsed DCs. Injection of antigen-pulsed DCs led to a severalfold increase in freshly isolated MP-specific, IFN-γ-secreting CD8+ T cells in all 6 HLA- A*0201-positive subjects, as early as 7 days after injection. When T cells were boosted in culture, there was an increase in MHC tetramer-binding cells and cytotoxic T cells after DC vaccination. These data provide the first controlled evidence of the immunogenicity of DCs in humans, and demonstrate that a single injection of mature DCs rapidly expands T-cell immunity

Selective blockade of the inhibitory Fcγ receptor (FcγRIIB) in human dendritic cells and monocytes induces a type I interferon response program

The ability of dendritic cells (DCs) to activate immunity is linked to their maturation status. In prior studies, we have shown that selective antibody-mediated blockade of inhibitory FcγRIIB receptor on human DCs in the presence of activating immunoglobulin (Ig) ligands leads to DC maturation and enhanced immunity to antibody-coated tumor cells. We show that Fcγ receptor (FcγR)-mediated activation of human monocytes and monocyte-derived DCs is associated with a distinct gene expression pattern, including several inflammationassociated chemokines, as well as type 1 interferon (IFN) response genes, including the activation of signal transducer and activator of transcription 1 (STAT1). FcγR-mediated STAT1 activation is rapid and requires activating FcγRs. However, this IFN response is observed without a detectable increase in the expression of type I IFNs themselves or the need to add exogenous IFNs. Induction of IFN response genes plays an important role in FcγR-mediated effects on DCs, as suppression of STAT1 by RNA interference inhibited FcγR-mediated DC maturation. These data suggest that the balance of activating/inhibitory FcγRs may regulate IFN signaling in myeloid cells. Manipulation of FcγR balance on DCs and monocytes may provide a novel approach to regulating IFN-mediated pathways in autoimmunity and human cancer

Erratum: Selective blockade of the inhibitory Fcγ receptor (FcγRIIB) in human dendritic cells and monocytes induces a type I interferon response program

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Correction

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Vigorous Premalignancy-specific Effector T Cell Response in the Bone Marrow of Patients with Monoclonal Gammopathy

Most approaches targeting the immune system against tumors have focused on patients with established tumors. However, whether the immune system can recognize preneoplastic stages of human cancer is not known. Here we show that patients with preneoplastic gammopathy mount a vigorous T cell response to autologous premalignant cells. This preneoplasia-specific CD4+ and CD8+ T cell response is detected in freshly isolated T cells from the BM. T cells from myeloma marrow lack this tumor-specific rapid effector function. These data provide direct evidence for tumor specific immune recognition in human preneoplasia and suggest a possible role for the immune system in influencing the early growth of transformed cells, long before the development of clinical cancer

Enhancement of clonogenicity of human multiple myeloma by dendritic cells

Infiltration by dendritic cells (DCs) is a common feature of most human tumors. Prior studies evaluating the interaction of DCs with tumors have focused largely on their immunologic properties (for review see Banchereau, J., and R.M. Steinman. 1998. Nature. 392:245–252). In this study, we show that the clonogenicity of several human tumor cell lines and primary tumor cells from myeloma patients is enhanced by their interactions with DCs. Myeloma cells cultured in the presence of DCs have an altered phenotype with an increased proportion of cells lacking terminal plasma cell differentiation marker CD138. DC–tumor interaction also leads to the up-regulation of B cell lymphoma 6 expression in myeloma cells. Effects of DCs on myeloma cells are inhibited by blockade of the receptor activator of NF-kB (RANK)–RANK ligand and B cell–activating factor–APRIL (a proliferation-inducing ligand)-mediated interactions. Together, these data suggest that tumor–DC interactions may directly impact the biology of human tumors, particularly multiple myeloma, and may be a target for therapeutic intervention

A Reversible Defect in Natural Killer T Cell Function Characterizes the Progression of Premalignant to Malignant Multiple Myeloma

We studied the function of antitumor T and natural killer T (NKT) cells from the blood and tumor bed in 23 patients with premalignant gammopathy, nonprogressive myeloma, or progressive multiple myeloma. We show that antitumor killer T cells can be detected in patients with both progressive or nonprogressive myeloma. Vα24+Vβ11+ invariant NKT cells are detectable in the blood and tumor bed of all cohorts. However, freshly isolated NKT cells from both the blood and tumor bed of patients with progressive disease, but not nonprogressive myeloma or premalignant gammopathy, have a marked deficiency of ligand-dependent interferon-γ production. This functional defect can be overcome in vitro using dendritic cells pulsed with the NKT ligand, α-galactosylceramide (α-GalCer). Fresh myeloma cells express CD1d, and can be efficiently killed by autologous NKT cells. We hypothesize that presentation of tumor derived glycolipids by myeloma cells leads to NKT dysfunction in vivo. These data demonstrate that clinical progression in patients with monoclonal gammopathies is associated with an acquired but potentially reversible defect in NKT cell function and support the possibility that these innate lymphocytes play a role in controlling the malignant growth of this incurable B cell tumor in patients