The human breast tumor microenvironment can display features of T helper type 2 (Th2) inflammation, and Th2 inflammation can promote tumor development. However, the molecular and cellular mechanisms contributing to Th2 inflammation in breast tumors remain unclear. Here, we show that human breast cancer cells produce thymic stromal lymphopoietin (TSLP). Breast tumor supernatants, in a TSLP-dependent manner, induce expression of OX40L on dendritic cells (DCs). OX40L(+) DCs are found in primary breast tumor infiltrates. OX40L(+) DCs drive development of inflammatory Th2 cells producing interleukin-13 and tumor necrosis factor in vitro. Antibodies neutralizing TSLP or OX40L inhibit breast tumor growth and interleukin-13 production in a xenograft model. Thus, breast cancer cell-derived TSLP contributes to the inflammatory Th2 microenvironment conducive to breast tumor development by inducing OX40L expression on DCs.

Aging is linked to deficiencies in immune responses and increased systemic inflammation. To unravel the regulatory programs behind these changes, we applied systems immunology approaches and profiled chromatin accessibility and the transcriptome in PBMCs and purified monocytes, B cells, and T cells. Analysis of samples from 77 young and elderly donors revealed a novel and robust aging signature in PBMCs, with simultaneous systematic chromatin closing at promoters and enhancers associated with T cell signaling and a potentially stochastic chromatin opening mostly found at quiescent and repressed sites. Combined analyses of chromatin accessibility and the transcriptome uncovered immune molecules activated/inactivated with aging and identified the silencing of the IL7R gene and the IL-7 signaling pathway genes as potential biomarkers. This signature is borne by memory CD8+ T cells, which exhibited an aging-related loss in binding of NF-κB and STAT factors. Thus, our study provides a unique and comprehensive approach to identifying candidate biomarkers and provides mechanistic insights into aging-associated immunodeficiency.

Mantle cell lymphoma (MCL) is a distinct clinical pathologic subtype of B cell non-Hodgkin's lymphoma often associated with poor prognosis. New therapeutic approaches based on boosting anti-tumor immunity are needed. MCL is associated with overexpression of cyclin D1 thus rendering this molecule an interesting target for immunotherapy.

Many vaccines induce protective immunity via antibodies. Systems biology approaches have been used to determine signatures that can be used to predict vaccine-induced immunity in humans, but whether there is a 'universal signature' that can be used to predict antibody responses to any vaccine is unknown. Here we did systems analyses of immune responses to the polysaccharide and conjugate vaccines against meningococcus in healthy adults, in the broader context of published studies of vaccines against yellow fever virus and influenza virus. To achieve this, we did a large-scale network integration of publicly available human blood transcriptomes and systems-scale databases in specific biological contexts and deduced a set of transcription modules in blood. Those modules revealed distinct transcriptional signatures of antibody responses to different classes of vaccines, which provided key insights into primary viral, protein recall and anti-polysaccharide responses. Our results elucidate the early transcriptional programs that orchestrate vaccine immunity in humans and demonstrate the power of integrative network modeling.

Early clinical trials, mostly in the setting of melanoma, have shown that dendritic cells (DCs) expressing tumor antigens induce some immune responses and some clinical responses. A major difficulty is the extension to other tumors, such as breast carcinoma, for which few defined tumor-associated antigens are available. We have demonstrated, using both prostate carcinoma and melanoma as model systems, that DCs loaded with killed allogeneic tumor cell lines can induce CD8+ T cells to differentiate into cytotoxic T lymphocytes (CTLs) specific for shared tumor antigens.

The ability of dendritic cells (DCs) to take up whole tumor cells and process their antigens for presentation to T cells ('cross-priming') is an important mechanism for induction of tumor specific immunity.

We previously reported (Bell, D., P. Chomarat, D. Broyles, G. Netto, G.M. Harb, S. Lebecque, J. Valladeau, J. Davoust, K.A. Palucka, and J. Banchereau. 1999. J. Exp. Med. 190: 1417-1426) that breast cancer tumors are infiltrated with mature dendritic cells (DCs), which cluster with CD4(+) T cells. We now show that CD4(+) T cells infiltrating breast cancer tumors secrete type 1 (interferon gamma) as well as high levels of type 2 (interleukin [IL] 4 and IL-13) cytokines. Immunofluorescence staining of tissue sections revealed intense IL-13 staining on breast cancer cells. The expression of phosphorylated signal transducer and activator of transcription 6 in breast cancer cells suggests that IL-13 actually delivers signals to cancer cells. To determine the link between breast cancer, DCs, and CD4(+) T cells, we implanted human breast cancer cell lines in nonobese diabetic/LtSz-scid/scid beta2 microglobulin-deficient mice engrafted with human CD34(+) hematopoietic progenitor cells and autologous T cells. There, CD4(+) T cells promote early tumor development. This is dependent on DCs and can be partially prevented by administration of IL-13 antagonists. Thus, breast cancer targets DCs to facilitate its development.

Mice repopulated with human hematopoietic cells are a powerful tool for the study of human hematopoiesis and immune function in vivo. However, existing humanized mouse models cannot support development of human innate immune cells, including myeloid cells and natural killer (NK) cells. Here we describe two mouse strains called MITRG and MISTRG, in which human versions of four genes encoding cytokines important for innate immune cell development are knocked into their respective mouse loci. The human cytokines support the development and function of monocytes, macrophages and NK cells derived from human fetal liver or adult CD34(+) progenitor cells injected into the mice. Human macrophages infiltrated a human tumor xenograft in MITRG and MISTRG mice in a manner resembling that observed in tumors obtained from human patients. This humanized mouse model may be used to model the human immune system in scenarios of health and pathology, and may enable evaluation of therapeutic candidates in an in vivo setting relevant to human physiology.

Dendritic cells (DCs) initiate and control immune responses. Plasmacytoid DCs (pDCs) represent a unique DC subset able to promptly release large amounts of type I interferon (IFN-alphabeta) upon viral encounter. Here we report that depletion of pDCs from human blood mononuclear cells abrogates the secretion of specific and polyclonal IgGs in response to influenza virus. Furthermore, purified pDCs triggered with virus induce CD40-activated B cells to differentiate into plasma cells. Two pDC cytokines act sequentially, with IFN-alphabeta generating non-Ig-secreting plasma blasts and IL-6 inducing their differentiation into Ig-secreting plasma cells. These plasma cells display the high levels of CD38 found on tissue plasma cells. Thus, pDCs are critical for the generation of plasma cells and antibody responses.

Cancer vaccines aim at inducing (a) tumor-specific effector T cells able to reduce/eliminate the tumor mass, and (b) long-lasting tumor-specific memory T cells able to control tumor relapse. We have shown earlier, in 18 human histocompatibility leukocyte antigen (HLA)-A*0201 patients with metastatic melanoma, that vaccination with peptide-loaded CD34-dendritic cells (DCs) leads to expansion of melanoma-specific interferon gamma-producing CD8+ T cells in the blood. Here, we show in 9 out of 12 analyzed patients the expansion of cytolytic CD8+ T cell precursors specific for melanoma differentiation antigens. These precursors yield, upon single restimulation with melanoma peptide-pulsed DCs, cytotoxic T lymphocytes (CTLs) able to kill melanoma cells. Melanoma-specific CTLs can be grown in vitro and can be detected in three assays: (a) melanoma tetramer binding, (b) killing of melanoma peptide-pulsed T2 cells, and (c) killing of HLA-A*0201 melanoma cells. The cytolytic activity of expanded CTLs correlates with the frequency of melanoma tetramer binding CD8+ T cells. Thus, CD34-DC vaccines can expand melanoma-specific CTL precursors that can kill melanoma antigen-expressing targets. These results justify the design of larger follow-up studies to assess the immunological and clinical response to peptide-pulsed CD34-DC vaccines.