dendritic cell, HLA system, immunostimulation, langerhans cell, monocyte, t lymphocyte activation
A procedure has been developed to isolate dendritic cells to a high degree of purity from fresh blood. Prior enrichment methods have relied upon an initial 1-2-d culture period. Purified fresh isolates lack the characteristic morphology, phenotype, and immunostimulatory function of dendritic cells. The purified cells have the appearance of medium sized lymphocytes and express substantial levels of CD4, but lack the T cell molecules CD3, CDS, and T cell receptor. When placed in culture, the cells mature in a manner resembling the previously described, cytokine-dependent maturation of epidermal dendritic cells (Langerhans cells). The ceils enlarge and exhibit many cell processes, express much higher levels of major histocompatibility complex class II and a panel of accessory molecules for T cell activation, and become potent stimulators of the mixed leukocyte reaction. Among the many changes during this maturation process are a fall in CD4 and the appearance of high levels of B7/BB1, the costimulator for enhanced interleukin 2 production in T cells. These changes are not associated with cell proliferation, but are dependent upon the addition of monocyte-conditioned medium. We suggest that the freshly isolated CD4-positive blood dendritic cells are recent migrants from the bone marrow, and that subsequent maturation of the lineage occurs in tissues in situ upon appropriate exposure to cytokines.
O’doherty, U., R. M. Steinman, M. Peng, P. U. Cameron, S. Gezelter, I. Kopeloff, W. J. Swiggard, M. Pope, and N. Bhardwaj. 1993. "Dendritic Cells Freshly Isolated from Human Blood Express CD4 and Mature into Typical Immtmostimulatory Dendritic Cells After Culture in Monocyte-Conditioned Medium." Journal of Experimental Medicine 178 (3): 1067-1078