This invention provides methods to prepare and use immunostimulatory cells for enhancing an immune response. The invention provides a method for preparing mature dendritic cells (DCs), comprising the sequential steps of: (a) signaling isolated immature dendritic cells (iDCs) with a first signal comprising an interferon gamma receptor (IFN-γR) agonist and/or a tumor necrosis factor alpha receptor (TNF-αR) agonist to produce signaled dendritic cells; and (b) signaling said signaled dendritic cells with a second transient signal comprising an effective amount of a CD40 agonist to produce CCR7.sup.+ mature dendritic cells. Also provided by this invention are enriched populations of dendritic cells prepared by the methods of the invention. Such dendritic cells have enhanced immunostimulatory properties and increased IL-12 secretion and/or decreased IL-10 secretion. CD40 signaling can be initiated by one or more of polypeptide translated from an exogenous polynucleotide encoding CD40L (e.g., mRNA or DNA), an agonistic antibody to CD40 receptor or by CD40 ligand polypeptide. The enriched populations can be further modified by the administration of an immunogen to the DC. The DC will take up and process the immunogen on its cell surface.

The invention relates in certain embodiments to a method for generating dendritic cells by employing temperatures below 37° C. during the development of progenitor cells and immature dendritic cells. In some embodiments the invention relates to populations of dendritic cells and its use.

Disclosed herein are new methods of producing a novel line of dendritic cells. The method comprises subjecting a sample of hematopoietic stem/precursor cells to a first feeder culture system that is supplemented with a first set of factors and a second feeder culture system supplemented with a second group of factors. The disclosure also pertains to new cell types that may be used as cancer immunotherapy.

The invention provides a quiescent stem cell having the capacity to differentiate into ectoderm, mesoderm and endoderm, and which does not express cell surface markers including MHC class I, MHC class II, CD44, CD45, CD13, CD34, CD49c, CD73, CD105 and CD90. The invention further provides a proliferative stem cell, which expresses genes including Oct-4, Nanog, Sox2, GDF3, P16INK4, BMI, Notch, HDAC4, TERT, Rex-1 and TWIST but does not express cell surface markers including MHC class I, MHC class II, CD44, CD45, CD13, CD34, CD49c, CD73, CD105 and CD90. The cells of the invention can be isolated from adult mammals, have embryonic cell characteristics, and can form embryoid bodies. Methods for obtaining the stem cells, as well as methods of treating diseases and the differentiated stem cells, are also provided.

The present invention provides methods of preparing a population of activated T cells by co-culturing T cells with dendritic cells loaded with a plurality of tumor antigen peptides. Also provided are methods of treating cancer in an individual using the activated T cells, pharmaceutical compositions and kits for cell-based cancer immunotherapy.

Compositions comprising dendritic cells pulsed with tumor lysate and at least one toll-like receptor (TLR) ligand which may be used for eliciting a specific immune response in a mammal in need thereof for treating diseases including a tumor are disclosed. Also disclose are methods of activating dendritic cells, comprising providing at least one toll-like receptor (TLR) ligand; and pulsing a dendritic cell with the at least one TLR ligand. A method further comprises pulsing the dendritic cell with a tumor lysate.

The invention pertains to a cell population for use in treating cancer in a patient, comprising CD1c (BDCA-1).sup.+/CD19.sup.− dendritic cells, wherein CD1c(BDCA-1).sup.+/CD19.sup.− dendritic cells are depleted for CD1c (BDCA-1).sup.+/CD197CD14.sup.+ cells.

The present invention provides methods of preparing a population of activated T cells by co-culturing T cells with dendritic cells loaded with a plurality of tumor antigen peptides. Also provided are methods of treating cancer in an individual using the activated T cells, pharmaceutical compositions and kits for cell-based cancer immunotherapy.

Disclosed are means, methods, and compositions of matter useful for enhancement of dendritic cell activity. In one embodiment the invention provides the use of GABA agonists such as homotaurine for stimulation of dendritic cell activity. In one embodiment said dendritic cell activity is enhancement of natural killer cell activity and/or of T cell activity. In one embodiment NK cell activity is ability to induce cytotoxicity in neoplastically transformed cells, whereas T cell activity is either cytokine production for CD4 cells or cytotoxicity for CD8 cells.

Provided herein are various engineered antigen presenting cells, methods of making them and methods of using them.