The prevention and treatment of prevalent infectious diseases and tumors should benefit from improvements in the induction of antigen-specific T cell immunity. To assess the potential of antigen targeting to dendritic cells to improve immunity, we incorporated ovalbumin protein into a monoclonal antibody to the DEC-205 receptor, an endocytic receptor that is abundant on these cells in lymphoid tissues. Simultaneously, we injected agonistic α-CD40 antibody to mature the dendritic cells. We found that a single low dose of antibody-conjugated ovalbumin initiated immunity from the naive CD4+ and CD8+ T cell repertoire. Unexpectedly, the αDEC-205 antigen conjugates, given s.c., targeted to dendritic cells systemically and for long periods, and ovalbumin peptide was presented on MHC class I for 2 weeks. This was associated with stronger CD8+ T cell–mediated immunity relative to other forms of antigen delivery, even when the latter was given at a thousand times higher doses. In parallel, the mice showed enhanced resistance to an established rapidly growing tumor and to viral infection at a mucosal site. By better harnessing the immunizing functions of maturing dendritic cells, antibody-mediated antigen targeting via the DEC-205 receptor increases the efficiency of vaccination for T cell immunity, including systemic and mucosal resistance in disease models.
Patients with multiple myeloma (MM) suffer from a general impaired immunity comprising deficiencies in humoral responses, T‐cell responses as well as dendritic cell (DC) function. Thus, to achieve control of tumour growth through immune therapy constitutes a challenge. Careful evaluation of the immune status in patients with MM seems crucial prior to active immune therapy. We evaluated the proportion of both, DC, Treg cells and myeloid‐derived suppressor cells (MDSC) in peripheral blood from patients with MM at diagnosis and in remission as well as patients with monoclonal gammopathy of undetermined significance (MGUS). We found that the proportion of both myeloid (m) DC and plasmacytoid (p) DC in patients at diagnosis was lowered compared to control donors, while only the proportion of pDC in patients in remission and with MGUS was significantly lower than in controls. The proportion of CD4+FOXP3+ Treg cells was increased in patients at diagnosis and not in patients in remission or with MGUS. Also, Treg cells from patients with MM were functionally intact as they were able to inhibit proliferation of both CD4 and CD8 T cells. Finally, we observed an increase in the proportion of CD14+HLA‐DR−/low MDSC in patients with MM at diagnosis, illustrating that this cell fraction is also distorted in patients with MM. Taken together, our results illustrate that, both mDC, pDC, Treg cells and MDSC are affected in patients with MM underlining the fact that the immune system is dysregulated as a consequence of the disease.
We evaluated the proposal that during microbial infection, dendritic cells (DCs) undergo maturation and present a mixture of peptides derived from the microbe as well as harmless environmental antigens. Mice were exposed to an aerosol of endotoxin free ovalbumin (OVA) in the absence or presence of influenza virus. In its absence, OVA failed to induce B and T cell responses and even tolerized, but with influenza, OVA-specific antibodies and CD8+ cytolytic T lymphocytes developed. With or without infection, OVA was presented selectively in the draining mediastinal lymph nodes, as assessed by the comparable proliferation of infused, CD8+ and CD4+, TCR transgenic T cells. In the absence of influenza, these OVA-specific T cells produced little IL-2, IL-4, IL-10, and IFN-γ, but with infection, both CD4+ and CD8+ T cells made high levels of IL-2 and IFN-γ. The OVA plus influenza-treated mice also showed accelerated recovery to a challenge with recombinant vaccinia OVA virus. CD11c+ DCs from the mediastinal lymph nodes of infected mice selectively stimulated both OVA- and influenza-specific T cells and underwent maturation, with higher levels of MHC class II, CD80, and CD86 molecules. The relatively slow (2–3 d) kinetics of maturation correlated closely to the time at which OVA inhalation elicited specific antibodies. Therefore respiratory infection can induce DC maturation and simultaneously B and T cell immunity to an innocuous antigen inhaled concurrently.
SummaryMultiple myeloma (MM) is a B cell cancer characterized by clonal proliferation in the bone marrow and impaired immunity. Because MM is an incurable malignancy, efficient consolidation is needed urgently. Targeting clonotypic B cells by idiotype vaccination has proved the principle to be effective and indicated that future strategies, including dendritic cell-based vaccination, could be a suitable approach. However, as MM patients suffer from a general impaired immunity, which may include dendritic cells (DCs), a careful evaluation of phenotypic traits and functionality of DCs from MM patients is necessary before an efficient vaccine can be developed. This study determined the number, phenotypic profile and functionality of myeloid and plasmacytoid DCs purified directly from blood from MM patients at diagnosis. A reduced number and lower expression of human leucocyte antigen (HLA) molecules was observed on both myeloid and plasmacytoid DCs in MM patients compared to healthy controls. Also, the expression of CCR5, CCR7 and DEC205 was lower in MM patients compared to normal donors. In addition, the capacity to stimulate allogeneic T cell proliferation and to stimulate cytokine production was decreased, suggesting that DCs from these patients are functionally impaired. Finally, the analysis of samples following chemotherapy and transplantation demonstrated an increased expression of HLA molecules, suggesting that this time-point is optimal for harvest and use in vaccination.
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