Differentiation of Human Hematopoietic Progenitor Cells Into Dendritic Cells In Vitro Under Stimulation of PPAR-Gamma

Author(s): Angela Silvano, Sara Paccosi, Maria Ida Bonetti, Astrid Parenti, Alberto Bosi, Paolo Romagnoli

The differentiation of dendritic cells (DCs) in vitro is not yet under full control and although PPAR-γ stimulation may interfere with DC differentiation from cord blood progenitors, the expression of PPAR-γ by different precursors and the effect of PPAR-γ stimulation on DC differentiation are poorly known. To address these issues, CD14+ monocytes, CD34+ progenitors and CD133+ progenitors were isolated from adult healthy donors and cultured with cytokines; rosiglitazone (1 μmol/l) was used to stimulate PPAR-γ. All precursors generated large, HLA-DR+ DCs, a proportion of which, highest when starting from CD133+ precursors expressed the Langerhans cell marker CD207/langerin; many cells expressed the connective tissue DC marker CD209/DC-SIGN, even together with CD207, and some cells contained Birbeck granules. Only CD133+ precursors expressed PPAR-γ mRNA appreciably; the DCs from these precursors contained a higher proportion of Langerhans like cells and caused 25% less stimulation of lymphocyte proliferation when generated in the presence of rosiglitazone. In conclusion, the phenotype of DCs differentiated in vitro does not match exactly that of DCs in vivo; PPAR-γ is expressed by freshly isolated CD133+ precursors; PPAR-γ agonists can direct DC differentiation from CD133+ precursors towards Langerhans type cells and inhibit the lymphocyte stimulating activity of the generated DCs.