IL-4 supports the generation of a dendritic cell subset from murine bone marrow with altered endocytosis capacity.

Dendritic cells (DC) of myeloid origin can be generated from mouse bone marrow (BM) using granulocyte macrophage-colony stimulating factor (GM-CSF). Immature major histocompatibility complex (MHC) II(low) DC are known to bear a high endocytosis capacity, in contrast to DC precursors and mature DC. Now we found that a subset of MHC II(low) DC in BM-DC cultures is unable to exert mannose receptor-mediated endocytosis of fluorescein isothiocyanate (FITC)-dextran (DX) and resembles immature Langerhans cells (LC). The FITC-DX endocytosis activity of LC-like cells occurs at an earlier stage of development, where the surface MHC II expression is absent or very weak. This LC-like subset expresses higher levels of E-cadherin but lower amounts of the markers Gr-1, scavenger receptor 2F8, and CD11b, when compared with the highly endocytic DC subset. The latter myeloid DC resemble monocyte-derived DC (MoDC). The sorted LC-like population develops completely and exclusively into mature MHC IIhigh DC, and the MoDC-like cells remain immature MHC II(low) DC or develop into adherent MHC IIneg macrophages or mature into MHC IIhigh DC. The development of LC-like cells is promoted by interleukin-4. Thus, we show here that the simultaneous development of LC-like and MoDC-like DC subsets occurs in standard bulk cultures with GM-CSF, suggesting the existence of two different precursors for LC and MoDC in BM.