Abstract: The present invention relates generally to methods for activating and expanding cells, and more particularly, to a novel method to activate and/or stimulate cells that maximizes the expansion of such cells to achieve dramatically high densities. In the various embodiments, cells are activated and expanded to very high densities in a short period of time. In certain embodiments, cells are activated and expanded to very high numbers of cells in a short period of time. Compositions of cells activated and expanded by the methods herein are further provided.

Abstract: The present invention relates generally to methods for stimulating, activating, and maintaining or increasing the polyclonality of expressed TCRs in a population of T cells. In the various embodiments, cells are stimulated with a surface, wherein the surface has attached thereto one or more agents that ligate a cell surface moiety of at least a portion of the T cells and stimulates at least a portion of the T cells, yielding enhanced proliferation, cell signal transduction, and/or cell surface moiety aggregation. In certain aspects methods for stimulating a population of cells such as T-cells, by cell surface moiety ligation are provided by contacting the population of cells with a surface, that has attached thereto one or more agents that ligate a cell surface moiety thereby inducing cell stimulation, cell surface moiety aggregation, and/or receptor signaling enhancement.

Abstract: Methods for increasing the number of human hematopoietic precursor cells in vitro are provided. The methods generally comprise (a) separating human hematopoietic precursor cells from mature hematopoietic cells present in a blood product; (b) inoculating the separated precursor cells into a culture vessel containing a culture medium comprising a nutritive medium and a source of growth factors at a density of between 1.times.10.sup.3 cells/ml and 4.times.10.sup.6 cells/ml; and (c) culturing the cells under conditions and for a time sufficient to increase the number of precursor cells relative to the number of such cells present in the blood product. The culture medium may also include a suitable amount of microcarrier beads. Suitable blood products include bone marrow, umbilical cord blood, and peripheral blood. A device for carrying out such methods is also provided.

Abstract: A method is provided for removing a second ligand from a particle surface without substantially affecting the particle surface, comprising the step of exposing the particle to a first ligand immobilized onto a support, wherein the particle is exposed under conditions and for a residence time sufficient to allow the second ligand to desorb from the particle surface, and wherein the first ligand has an affinity for the second ligand that is at least two orders of magnitude greater than the affinity of the second ligand for the particle surface, such that the second ligand is removed from the particle surface without substantially affecting the particle surface.

Abstract: The selectivity of immunoselection systems employing insolubilized avidin and biotinylated specific antibody is amplified, and nonspecific recovery is improved, by employing an indirect sandwich technique using a biotin-conjugated antispecies immunoglobulin that is directed to one or more nonbiotinylated specific antibodies in conjunction with insolubilized avidin. Specific cell populations can be removed and recovered from bone marrow, providing excellent recovery of bone marrow and preservation of hematopoietic stem cells for transplantation. Mixed populations of T cells or of tumor cells can be conveniently and simultaneously removed with minimal manipulation of the marrow cells. An improved positive immunoselection method provides viable and functional recovered cells, e.g., hematopoietic stem cells or activated killer cells, that can be clinically employed.

Abstract: The selectivity of immunoselection systems employing insolubilized avidin and biotinylated specific antibody is amplified, and nonspecific recovery is improved, by employing an indirect sandwich technique using a biotin-conjugated antispecies immunoglobulin that is directed to one or more nonbiotinylated specific antibodies in conjunction with insolubilized avidin. Specific cell populations can be removed and recovered from bone marrow, providing excellent recovery of bone marrow and preservation of hematopoietic stem cells for transplantation. Mixed populations of T cells or of tumor cells can be conveniently and simultaneously removed with minimal manipulation of the marrow cells. An improved positive immunoselection method provides viable and functional recovered cells, e.g., hematopoietic stem cells or activated killer cells, that can be clinically employed.

Abstract: The selectivity of immunoselection systems employing insolubilized avidin and biotinylated specific antibody is amplified, and nonspecific recovery is improved, by employing an indirect sandwich technique using a biotin-conjugated antispecies immunoglobulin that is directed to one or more nonbiotinylated specific antibodies in conjunction with insolubilized avidin. Specific cell populations can be removed and recovered from bone marrow, providing excellent recovery of bone marrow and preservation of hematopoietic stem cells for transplantation. Mixed populations of T cells or of tumor cells can be conveniently and simultaneously removed with minimal manipulation of the marrow cells. An improved positive immunoselection method provides viable and functional recovered cells, e.g., hematopoietic stem cells or activated killer cells, that can be clinically employed.