Dendritic cells (DCs) are the initiators and regulators of both innate and adaptive immunity. They are the most potent professional antigen-presenting cells (APCs).

There are various subtypes of DCs with distinct functional characteristics. CD141⁺ DCs are the most promising for anti-tumour purposes as they excel at recognition of intracellular and necrotic cell antigens, and are also superior at cross-presenting antigens to Cytotoxic T-cell Lymphocytes (CTLs). However, the underlying mechanisms of activation and stimulation are still not fully elucidated due to the rarity of these cells (about 0.03% of the circulating peripheral blood mono-nuclear cells).

To overcome this limitation, we have established a culture model to generate rare CD141⁺ DCs from human CD34⁺ cord blood haematopoietic stem cells using a 2 step expansion and differentiation process in a cocktail of cytokines. In this system, CD34⁺ cell numbers expand over 50 fold in the course of one week. We were also able to differentiate these cells into CD141⁺ DCs with a yield of about 40 CD141⁺ DC from each CD34⁺ cell. In vitro derived CD141⁺ DCs expressed known markers for this subset including CLEC9A and CADM1. Following ligation of the TLR3 ligand, poly I:C, in vitro generated CD141⁺ DC upregulated expression of costimulatory molecules CD40, CD80, CD83 and CD86, and produced large quantities of hallmark cytokine IFN-λ.

These data demonstrate that large numbers of functional CD141⁺ DC can be differentiated in vitro, making this a practical and robust model to further explore the biology of this rare cell population.