GENERATION OF IMMUNOSTIMULATORY DENDRITIC CELLS FROM HUMAN CD34-MARROW AND PERIPHERAL-BLOOD( HEMATOPOIETIC PROGENITOR CELLS OF THE BONE)

Dendritic antigen-presenting cells are considered to be the most effec tive stimulators of T cell immunity. The use of dendritic cells has be en proposed to generate therapeutic T cell responses to tumor antigens in cancer patients. One limitation is that the number of dendritic ce lls in peripheral blood is exceedingly low. Dendritic cells originate from CD34(+) hematopoietic progenitor cells (HPC) which are present in the bone marrow and in small numbers in peripheral blood. CD34(+) HPC can be mobilized into the peripheral blood by in vivo administration of granulocyte-colony-stimulating factor. The aim of the current study was to determine whether functional dendritic cells could be elicited and grown in vitro from CD34(+) HPC derived from bone marrow or granu locyte-colony-stimulating factor-mobilized peripheral blood. Culture o f CD34(+) HPC with granulocyte-macrophage-colony-stimulation factor an d tumor necrosis factor alpha yielded a heterogeneous cell population containing cells with typical dendritic morphology. Phenotypic studies demonstrated a loss of the CD34 molecule over 1 week and an increase in cells expressing surface markers associated with dendritic cells, C D1a, CD80 (B7/BB1), CD4, CD14, HLA-DR, and CD64 (Fc gamma RI). Functio n was validated in experiments showing that cultured cells could stimu late proliferation of allogeneic CD4(+) and CD8(+) T lymphocytes. Anti gen-presenting capacity was further confirmed in experiments showing t hat cultured cells could effectively stimulate tetanus toxoid-specific responses and HER-2/neu peptide-specific responses. The derivation an d expansion of dendritic cells from cultured bone marrow or granulocyt e-colony-stimulating factor-mobilized CD34+ HPC may provide adequate n umbers for testing of dendritic cells in clinical studies, such as vac cine and T cell therapy trials.