Potent Presentation of Soluble Protein Antigens by In Vitro-Generated Dendritic Cells from Peripheral Blood CD34⁺ Progenitor Cells

Abstract

Dendritic cells (DC) are potent antigen-presenting cells (APC) and thus are specifically involved in the initiation of antigen-specific immune responses. Due to their potent costimulatory activity, they are well suited to prime naive T cells to various antigens (Ag), such as viral peptides, tumor-, or allo-antigens. In line with their crucial role in the host defense system, they are located in the epithelial borders of the body, where they take up Ag and then migrate into the lymph nodes to recruit T cells [1]. DCs originate from hematopoietic progenitor cells, and it has been shown recently that they can be generated from cord blood and peripheral blood progenitor cells (PBPC) in vitro by using granulocyte-macrophage colony-stimulating factor (GM-CSF) in conjunction with interleukin-4 (IL-4; [3]) or tumor necrosis factor-α (TNF—α [2]). By adding GM-CSF and IL-4 to a combination of early acting hematopoietic growth factors we observed a ten-fold increase in the number of DCs derived from CD34⁺ PBPCs compared with GM-CSF plus IL-4 or TNF-α alone [3]. In addition, large numbers of Birbeck-granule-positive “Langerhans-like” cells (LC) which are thought to be the immediate precursors of mature DCs, emerged under these conditions. Here we have analyzed the functional capacity of these cells to take up, process, and present a soluble protein antigen.