Regulation by allergens of chemokine receptor expression on in vitro-generated dendritic cells.

Immature dendritic cells (DCs) derived from CD34+ progenitor cells or peripheral monocytes, are used as in vitro sensitization models in many chemical allergen treatment studies. During the sensitization, DCs follow maturation process and gain the capacity to migrate to lymph nodes where they stimulate T cells. Chemokine receptor allows DCs to migrate along chemotactic gradients. In this work, we used immature DCs from peripheral monocytes to evaluate the influence of allergens on chemokine receptor and surface-marker expression. We tested the sensitizers dinitrochlorobenzene, Bandrowski's base, and coumarin, as well as the tolerogen dichloronitrobenzene, the irritant sodium dodecyl sulfate and the solvent dimethyl sulfoxide. All skin sensitizers up-regulated the co-stimulatory molecule CD86 and increased the CD83+ cell population. No expression of the chemokine receptors CCR2, CCR3, CCR6, or CXCR5 was observed on DCs exposed to the tested chemicals. The strong allergen dinitrochlorobenzene slightly increased CCR7 expression on DCs but down-regulated CCR1 surface expression. CCR1 down-regulation was not mediated by a classical maturation pathway, as it was unaffected by the corticosteroid dexamethasone.

Stimulation of peripheral blood and intestinal mucosa cells by synthetic CpG oligodeoxynucleotides.

The breakdown of tolerance to autologous bacterial flora has been implicated as a major factor contributing to the initiation and perpetuation of chronic inflammation in inflammatory bowel diseases (IBD). To test whether bacterial DNA is at the origin of inflammation in IBD, we have examined the response of lamina propria (LPMC) or peripheral mononuclear cells (PBMC) and purified T cells from IBD patients and control patients to stimulations with a set of oligodeoxynucleotides (ODNs) characterized by the presence or absence of cytosine-guanosine dinucleotides (CpG) and/or 3' poly-guanosine (poly-G) extension. Furthermore we have evaluated the costimulatory activities of these ODNs on T cells activated via CD2 or CD3 pathway. We demonstrated that CpG ODNs induce higher proliferation of LPMC from inflammatory intestinal mucosa compared to healthy mucosa. We confirmed that CpG ODNs do not directly costimulate peripheral blood T cells activated by CD3 pathway. Finally, we revealed that CpG or non-CpG ODNs with 3' poly-G extension inhibit completely CD2 activation of purified PB or LP T-cells whereas only CpG ODNs without poly-G extension enhance proliferation and IFN-gamma production of PB T cells stimulated by CD2 pathway only in presence of NK and NK T cells. Our data suggest that NK T cells may be the primary target of ODNs and play a crucial role in indirect T-cell activation by ODN.