blood and hemopoietic system, cell separation, Langerhans cell, leukocyte
Previous studies demonstrated that lymphoid tissues of mice and rats contain small numbers (<1% of nucleated cells) of dendritic cells (DC) with special cytologic surface, and functional properties. We show here that similar DC represent 0.1-0.5% of human peripheral blood mononuclear cells. DC can be enriched to 20-60% purity by a multistep procedure analogous to that used in mice. Adherent peripheral blood mononuclear cells are cultured overnight, and the released cells are depleted of monocytes and B cells by readherence to plastic, rosetting with erythrocytes coated with anti-human IgG, and centrifugation in dense albumin columns. Enriched DC have similar cytologic features to rodent DC by light and electron microscopy. DC express HLA, and HLA-DR and the leukocyte-common antigens. They lack phagocytic capacity, receptors for antibody-coated and neuraminidase-treated erythrocytes, surface and intracellular Ig, esterase, peroxidase, and azurophilic granules. DC do not react with several monoclonal antibodies directed to phagocytes (OKM 1, 'mac-1,' 63D3, and 61D3) and T cells (OKT 3, 6, 8). Unlike the mouse, human DC express complement receptors. When maintained in culture for 4 d, human DC did not give rise to either B cells or monocytes. Therefore, DC identified by cytologic criteria are distinct from other leukocytes. Enriched populations of DC have been compared to fractions enriched in monocytes, B cells, and T cells in three functional assays: stimulation of the primary allogeneic mixed leukocyte reaction, stimulation of the primary syngeneic MLR, and accessory function for the proliferation of periodate-modified T cells. In each case, the DC fraction was 10-fold or more active than other cell fractions. We conclude that DC circulate in man, and represent the principal cell type-required for the initiation of several immune responses.
Van Voorhis, W. C., L. S. Hair, R. M. Steinman, and G. Kaplan. 1982. "Human Dendritic Cells. Enrichment and Characterization from Peripheral Blood." Journal of Experimental Medicine 155 (4): 1172-1187