Myeloid blood dendritic cells and monocyte-derived dendritic cells differ in their endocytosing capability.

Human dendritic cells (DCs) constitute a heterogeneous population of antigen-presenting cells characterized by a unique capacity to stimulate naïve T cells. The functions of DCs depend on the particular subset and in this study we compare two types of myeloid DCs: freshly isolated blood mDCs and in vitro generated monocyte-derived DCs (MoDCs), in their ability to accomplish endocytosis. In our hands, these two DC subtypes showed similarities in the expression of surface markers, but displayed clear differences in endocytic capacity. Freshly isolated blood mDCs showed a high propensity to capture and endocytose particles compared to in vitro generated MoDCs. The blood mDCs also showed a clear receptor-enhanced endocytosis when zeolite particles were co-adsorbed with IgG. On the other hand, the MoDCs differed remarkably compared to blood mDCs in the capture of ovalbumin and immune complexes. Interestingly, the MoDCs showed low endocytosis of IgG-coated particles but an efficient capture of immune complexes. The MoDCs also showed a high capacity to capture ovalbumin although with a relatively low degree of internalization. These data indicate distinct differences in the early process of endocytosis featured by mDCs and MoDCs, which is important to consider when choosing DC populations for future functional or clinical applications.