Dendritic cells (DC) are recruited to sites of inflammation for the initiation of immune responses. After addition of TNF- to the culture medium, the majority of the CD1a+ cells expressed CD83+. These cells C expressing a phenotype of mature DC C down-regulated the expression of the anaphylatoxin receptors and lost their reactivity to the respective ligands. Our results demonstrate the expression of the anaphylatoxin receptors C5aR and C3aR on human skin-derived DC and blood-derived cells expressing the DC-associated membrane molecule, CD1a. Furthermore, the expression of anaphylatoxin receptors on CD83+ dermal DC is indicative of BTZ043 an intermediate stage of maturation of these cells, which was not observed on for 30 min. The cells from the interface were washed twice and cultured for 2 days in RPMI +10% FCS. Dermal tissue was incubated in Hank’s solution (4 hr at 37) containing 01% collagenase, 20 g/ml of DNAse, 12 U/ml of dispase, 01% hyaluronidase and 10% FCS. The cell suspension was filtered through nylon gauze. The cells were washed three times and cultured for 2 days in RPMI +10% FCS. Preparation of monocyte-derived DCPeripheral blood mononuclear cells (PBMC) were isolated by Lymphoprep density-gradient centrifugation of heparinized leucocyte-enriched buffy coats. Highly purified monocytes were obtained by elutriation, using a Beckmann E-6B centrifuge equipped with an elutriation rotor. The flow rate of the elution medium was adjusted to 18 ml/min. The centrifugation speed was reduced BTZ043 step-by-step from 975 to 344 and the cells were collected in 200-ml fractions. Cells collected as such were analysed by flow cytometry (Becton-Dickinson, Heidelberg, Germany). Most of the monocytes were enriched in the fraction obtained at 381 Platelets were obtained at 694 or slower, small lymphocytes at 548 and a monocyte/lymphocyte mixture at 440 maturation of epidermal SRSF2 Langerhans’ cells after a short-term culture together with keratinocytes in the presence of GM-CSF. The authors, however, did not investigate CD83+ dermal DC, which we found to also BTZ043 express C5aR+. In our experiments, skin-derived DC, which were further treated with TNF- (although they express CD83, the marker for mature DCs) represent an interconverting population in the skin and that the final differentiation depends upon the prevailing cytokine environment. The reason for the differential expression of C5aR on dermal CD83+ DC and monocyte-derived CD83+ cells is unknown at present. Immature DC, identified by the expression of CD1a and defined by the lack of CD83, have the capacity to produce a large number of cytokines that contribute to T-cell priming (IL-1a, IL-6, IL-15, TNF-) or to T-cell maturation (IL-12, IL-18, IL-7).47 Lore maturation.52 Immature DC express a number of receptors for inflammatory cytokines or chemokines, which may attract the cells to sites of inflammation.12 Upon further maturation by stimulation with TNF-, dermal DC regulate these receptors. This may allow them to emigrate from the inflammatory site. It seems to be that the CD83+ dermal DC are probably immature cells rather than terminal mature cells. BTZ043 The expression of C5aR and the calcium fluxes observed upon stimulation with C5a indicate a specific response of dermal CD83+ cells to the anaphylatoxin C5a. This is of considerable biological interest because, in experimental models using blood-derived mononuclear cells, C5a has been shown to have immunoregulatory properties. The stimulation of mononuclear cells with lipopolysaccharide (LPS) or IL-1, together with C5a, leads to an increased synthesis of IL-1, IL-6 and TNF.22,53,54 Furthermore, C5a has been described as a chemoattractant for myeloid cells (such as neutrophils, eosinophils, basophils and monocytes) and for DC generated by treatment of PBMC with GM-CSF + IL-4.9,19 Another important effect of C5a is the degranulation of monocytes and granulocytes, which liberates many enzymes and rapidly changes the cell.