De Smedt, A., Van Den Heuvel, R., Schoeters, G., and B. Zwi. Phenotypic and Functional Characterisation of Dendritic Cells Derived from Human Cord Blood CD34⁺ Haematopoietic Progenitor Cells: an In Vitro Model for Skin Sensitisation? ATLA. 1999. 27: 360.

dinitrochlorobenzene - 25567-67-3; 2,4,6-trinitrobenzenesulphonic acid - 2508-19-2; sodium dodecyl sulphate - 00151-21-3;

Dendritic cells (DC) are highly specialised antigen-presenting cells of the immune system. DC pick up and process antigen, with high efficiency in peripheral tissues (for example, the skin) and migrate to lymphoid organs to present these antigens to specific T-cells. DC preferentially induce the development of T helper cells type 1 (Th1), after processing sensitising antigens, and therefore are regarded as important initiators of primary Th1 specific immune responses such as skin contact dermatitis. This study was focused on the generation of dendritic cells starting from human cord blood-derived CD34⁺ progenitor cells. We examined the conditions under which human cord blood derived CD34⁺ cells, proliferated and differentiated into dendritic cells. Primitive stem cells were isolated from mononuclear cells, by positive selection using immunomagnetic microbeads. A two-stage culture system was used (as described by Lardon et al. Immunology 91, 553-559, 1997). During the first 5 days, CD34⁺ cells (10⁵ cells/ml) were cultured in the presence of 500ng/ml GM-SCF, 2.5ng/ml TNF-α and 50ng/ml SCF. 1000IU/ml interleukin-4 was added during the second stage of the culture period for 5-9 days. The definition of DC was based on: the typical dendritic morphology; the low surface expression of CD14, the high surface expression of CD1a and HLA-DR and co-stimulary molecules such as CD80, CD83 and CD86; the stimulatory capacity for naïve T-cells in the autologous mixed lymphocyte reaction (MLR); and the potency to produce cytokines such a Il-1ß and Il-12 (ELISA and RT-PCR). Preliminary research evaluated the capacity of this culture system to be used as an in vitro model to discriminate between the sensitising and irritant potential of a substance. Phenotypical and functional alterations of DC under the influence of sublethal concentrations of contact sensitisers (NiCl₂, dinitrochlorobenzene, 2, 4, 6-trinitrobenzenesulphonic acid), and the irritant, sodium dodecyl sulphate, were studied.