In Vitro Generation of Functional Human and Murine Dendritic Cells

Dendritic cells (DC) that reside in tissues such as the epidermis, lung, or spleen, and those that circulate in the blood, are functionally and phenotypi-cally immature (1 ,2 ). In this immature or precursor state, DCs can process protein antigens (Ags), and phagocytose and process particulate matter efficiently; however, they are poor stimulators of T-lymphocytes. As DCs migrate from the epidermis to the lymphoid organs, several phenotypic and functional changes occur: they acquire several co-stimulatory molecules; upregulate major histocompatibility complex class II (MHC-II), DEC-205 Ag receptor, and granule Ag M342; become less phagocytic; lose their protein-processing capabilities; and eventually become potent stimulators of T-lymphocytes. Similar to their in vivo properties, DCs freshly isolated from the blood, skin, or spleen are functionally and phenotypically immature, but after 1-2 d in culture,