Dendritic cells process internalized antigens to present degradative products on MHC for TCR recognition. Because antigen-exposed DCs also induce humoral immunity, DCs must also retain antigen in its native state for the engagement of BCR on B cells. Here, we demonstrate that antigen endocytosed by the inhibitory Fc receptor, FcgammaRIIB, accesses a non-degradative intracellular vesicular compartment that recycles to the cell surface, enabling interaction of native antigen with BCR on B cells. Immunization with IgG-opsonized, T independent antigens leads to enhanced humoral responses in a FcgammaRIIB and complement dependent manner. IC-loaded DCs trafficking to the splenic marginal zone can prime a T independent response in an FcgammaRIIB-dependent manner. Thus dendritic cells are equipped with both non-degradative and degradative antigen uptake pathways to facilitate antigen presentation to both B and T cells.

The pattern recognition receptor, RAGE, has been shown to be involved in adaptive immune responses but its role on the components of these responses is not well understood. We have studied the effects of a small molecule inhibitor of RAGE and the deletion of the receptor (RAGE−/− mice) on T cell responses involved in autoimmunity and allograft rejection. Syngeneic islet graft and islet allograft rejection was reduced in NOD and B6 mice treated with TTP488, a small molecule RAGE inhibitor (p < 0.001). RAGE−/− mice with streptozotocin-induced diabetes showed delayed rejection of islet allografts compared with wild type (WT) mice (p < 0.02). This response in vivo correlated with reduced proliferative responses of RAGE−/− T cells in MLRs and in WT T cells cultured with TTP488. Overall T cell proliferation following activation with anti-CD3 and anti-CD28 mAbs were similar in RAGE−/− and WT cells, but RAGE−/− T cells did not respond to costimulation with anti-CD28 mAb. Furthermore, culture supernatants from cultures with anti-CD3 and anti-CD28 mAbs showed higher levels of IL-10, IL-5, and TNF-α with RAGE−/− compared with WT T cells, and WT T cells showed reduced production of IFN-γ in the presence of TTP488, suggesting that RAGE may be important in the differentiation of T cell subjects. Indeed, by real-time PCR, we found higher levels of RAGE mRNA expression on clonal T cells activated under Th1 differentiating conditions. We conclude that activation of RAGE on T cells is involved in early events that lead to differentiation of Th1+ T cells.

We have developed a model of autoimmunity to investigate autoantibody-mediated cross-presentation of self antigen. RIP-mOVA mice, expressing OVA in pancreatic β cells, develop severe autoimmune diabetes when given OT-I cells (OVA-specific CD8 + T cells) and anti-OVA IgG but not when given T cells alone. Anti-OVA IgG is not directly injurious to the islets but rather enhances cross-presentation of apoptotic islet antigen to the OT-I cells, leading to their differentiation into potent effector cells. Antibody-driven effector T cell activation is dependent on the presence of activating Fc receptors for IgG (FcγRs) and cross-priming DCs. As a consequence, diabetes incidence and severity was reduced in mice lacking activating FcγRs. An intact complement pathway was also required for disease development, as C3 deficiency was also partially protective. C3-deficient animals exhibited augmented T cell priming overall, indicating a proinflammatory role for complement activation after the T cell priming phase. Thus, we show that autoreactive antibody can potently enhance the activation of effector T cells in response to cross-presented self antigen, thereby contributing to T cell-mediated autoimmunity.

Receptor for advanced glycation end products (RAGE) is an activation receptor triggered by inflammatory S100/calgranulins and high mobility group box-1 ligands. We have investigated the importance of RAGE on Ag priming of T cells in murine models in vivo. RAGE is inducibly up-regulated during T cell activation. Transfer of RAGE-deficient OT II T cells into OVA-immunized hosts resulted in reduced proliferative responses that were further diminished in RAGE-deficient recipients. Examination of RAGE-deficient dendritic cells did not reveal functional impairment in Ag presentation, maturation, or migratory capacities. However, RAGE-deficient T cells showed markedly impaired proliferative responses in vitro to nominal and alloantigens, in parallel with decreased production of IFN-γ and IL-2. These data indicate that RAGE expressed on T cells is required for efficient priming of T cells and elucidate critical roles for RAGE engagement during cognate dendritic cell-T cell interactions.

The uptake of immune complexes by FcRs on APCs augments humoral and cellular responses to exogenous Ag. In this study, CD11c+ dendritic cells are shown to be responsible in vivo for immune complex-triggered priming of T cells. We examine the consequence of Ab-mediated uptake of self Ag by dendritic cells in the rat insulin promoter-membrane OVA model and identify a role for the inhibitory FcγRIIB in the maintenance of peripheral CD8 T cell tolerance. Effector differentiation of diabetogenic OT-I CD8+ T cells is enhanced in rat insulin promoter-membrane OVA mice lacking FcγRIIB, resulting in a high incidence of diabetes. FcγRIIB-mediated inhibition of CD8 T cell priming results from suppression of both DC activation and cross-presentation through activating FcγRs. Further FcγRIIB on DCs inhibited the induction of OVA-specific Th1 effectors, limiting Th1-type differentiation and memory T cell accumulation. In these MHC II-restricted responses, the presence of FcγRIIB only modestly affected initial CD4 T cell proliferative responses, suggesting that FcγRIIB limited effector cell differentiation primarily by inhibiting DC activation. Thus, FcγRIIB can contribute to peripheral tolerance maintenance by inhibiting DC activation alone or by also limiting processing of exogenously acquired Ag.

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Fixed dose combination (FDC) products are common in the treatment of hypertension, diabetes, human immunodeficiency virus, and tuberculosis. They make it possible to combine two or more drug molecules with different modes of pharmacological actions in a single dosing unit and optimize the treatment. From a patient perspective, they offer convenience, reduced dosing unit burden, and cost savings. From a clinical perspective, aging population in developed countries will need multiple medications to treat age related diseases and co-morbidities. FDC products simplify dosing regimen and enhance patient compliance. As outlined in the article, the number of FDC products has grown over the years and the trend is likely to continue. This review article gives an overview to pharmaceutical scientists about recent trends in the formulation development of the FDC products and provides decision trees to select most optimum formulation development strategy. While some formulation technologies such as multi-layer tablets, multiparticulate systems, active film coating, and hot-melt granulation are discussed in more detail, a few specialized technologies are also introduced briefly to the readers.

Nivolumab is a fully human IgG4 monoclonal antibody targeting the programmed death-1 (PD-1) receptor that blocks interactions between PD-1 and its ligands on tumor cells to prevent T-cell exhaustion in patients with cancer. It has demonstrated efficacy in multiple tumor types, including melanoma, non-small-cell lung cancer, and renal cell carcinoma. This analysis assessed the immunogenicity of nivolumab and its impact on pharmacokinetics, safety, and efficacy in patients with solid tumors enrolled in 6 clinical studies. The incidence and prevalence of antidrug antibodies (ADAs) were determined by validated electrochemiluminescence assays in samples collected during nivolumab treatment and up to 100 days after the last dose. Confirmed positive samples from the 6 studies were also tested for presence of neutralizing antibodies (NAbs). Among 1086 nivolumab-treated patients, 138 patients (12.7%) were ADA positive (relative to baseline), only 3 (0.3%) of whom were persistently positive for ADA, and 9 (0.8%) were NAb positive at 1 time point. The presence of ADAs was not associated with hypersensitivity, infusion reactions, or loss of efficacy and had minimal impact on nivolumab clearance. Additionally, the presence of NAbs was not associated with loss of efficacy. In conclusion, immunogenicity of nivolumab is not clinically meaningful.