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Mixed Leucocyte Reaction (mixed + leucocyte_reaction)

Distribution by Scientific Domains

Medical Sciences	100%

Selected Abstracts

Paradoxical effects of interleukin-10 on the maturation of murine myeloid dendritic cells

IMMUNOLOGY, Issue 2 2003
Dianne L. Commeren
Summary The immunoregulatory cytokine, interleukin-10 (IL-10), has been shown to inhibit the maturation of human myeloid dendritic cells (DC). In the present study, we demonstrate that IL-10 has paradoxical effects on the maturation of murine myeloid bone marrow-derived DC. On the one hand, IL-10 inhibits the maturation of murine myeloid DC. The addition of IL-10 to granulocyte,macrophage colony-stimulating factor (GM-CSF)-supported murine BM-derived DC cultures reduced the frequency of major histocompatibility complex (MHC) class IIbright cells. These IL-10-pretreated DC have a reduced capacity to stimulate T cells in an allogeneic mixed leucocyte reaction. On the other hand, however, and in contrast to the effects of IL-10 on human DC, we found that the addition of IL-10 from the initiation of the culture onwards induced an up-regulation of the expression of the costimulatory molecules CD40, CD80 and CD86 on murine myeloid DC, as compared to DC generated with GM-CSF only. Moreover, a subpopulation of IL-10-pretreated MHC class IIdim DC lacked the capacity to take up dextran-fluorescein isothiocyanate (FITC), a feature of DC maturation. Taken together, our data demonstrate that the generation of murine myeloid DC in the presence of IL-10 results in a population of incompletely matured MHC class IIdim CD80+ CD86+ DC. These DC lack T-cell stimulatory capacity, suggesting a role for IL-10 in conferring tolerogenic properties on murine myeloid DC. [source]

Cilomilast, tacrolimus and rapamycin modulate dendritic cell function in the elicitation phase of allergic contact dermatitis

BRITISH JOURNAL OF DERMATOLOGY, Issue 1 2005
W. Bäumer
Summary Background, Cilomilast and tacrolimus as well as rapamycin are potential drugs for the treatment of allergic skin diseases like atopic dermatitis and allergic contact dermatitis. Objectives, To compare the in vitro and in vivo immunomodulatory effects of the phosphodiesterase 4 inhibitor cilomilast with those of tacrolimus and rapamycin. Methods, The in vitro action of cilomilast, tacrolimus and rapamycin were tested in a mixed leucocyte reaction (MLR). In vivo, the inhibitory action of the immunomodulatory drugs was compared in the toluene-2,4-diisocyanate (TDI)-induced allergic inflammatory response with particular focus on dendritic cell (DC) function. Results, Cilomilast, tacrolimus and rapamycin were all able to inhibit DC-mediated T-cell activation in a MLR. But it was demonstrated for cilomilast that the target cells are T cells rather than DC. In vivo, a combination of systemic and topical administration of each of these three substances significantly inhibited swelling in the murine ear 16 h after TDI challenge. There was also a reduction in the weight of the draining auricular lymph node, in lymphocyte cell count, and in the number of emigrated DC. The density of Langerhans cells in the epidermis was correspondingly higher in mice treated with cilomilast, tacrolimus and rapamycin than in those treated with vehicle. All three substances were found to inhibit DC migration ex vivo in a skin DC migration assay performed on ear tissue after TDI challenge. Conclusions, DC migration into the draining lymph node also takes place in the elicitation phase of allergic contact dermatitis and this migration can be influenced by tacrolimus and rapamycin, and, to a lesser extent, by cilomilast. [source]

Human cytomegalovirus induces a direct inhibitory effect on antigen presentation by monocyte-derived immature dendritic cells

BRITISH JOURNAL OF HAEMATOLOGY, Issue 1 2002
Ulrich Grigoleit
Summary. The hypothesis that productive infection of monocyte-derived immature dendritic cells (DCs) by the human cytomegalovirus (HCMV) is associated with decreased immunostimulatory capacity was tested in this study. DCs were infected with 60,80% efficiency by HCMV strain TB40/E. Infected versus uninfected cells were analysed by fluorescence-activated cell sorting and by immunocytochemistry for surface expression of major histocompatibility complex (MHC) and co-stimulatory molecules as well as cytokine secretion during the 3 d after infection. The immunostimulatory capacity of these cells was measured by mixed leucocyte reaction. In spite of the fact that HCMV infection of DCs induced an increased release of tumour necrosis factor-, (TNF-,) and a decreased interleukin 10 (IL-10) production, expression of MHC class I and II, as well as CD40 and CD80 molecules, were downregulated on infected DCs. The mixed leucocyte reaction showed significantly reduced immunostimulatory capacity of infected DC cultures. Simultaneous detection of MHC antigens and virus antigens by double immunofluorescence revealed that downregulation occurred only on infected cells, but not on uninfected bystander cells. These findings demonstrate on a single cell level, together with the marked downregulation of MHC and co-stimulatory molecules in the presence of high TNF-, and low IL-10 levels, a direct inhibitory effect of HCMV on antigen presentation by immature DCs independent of soluble mediators. [source]

Altered phenotype and function of dendritic cells in children with type 1 diabetes

CLINICAL & EXPERIMENTAL IMMUNOLOGY, Issue 2 2005
F. Angelini
Summary The importance of dendritic cells (DC) in the activation of T cells and in the maintenance of self-tolerance is well known. We investigated whether alterations in phenotype and function of DC may contribute to the pathogenesis of Type 1 diabetes (T1DM). Mature DC (mDC) from 18 children with T1DM and 10 age-matched healthy children were tested. mDC, derived from peripheral blood monocytes cultured for 6 days in presence of interleukin (IL)-4 and granulocyte-macrophage colony stimulating factor (GM-CSF) and stimulated with lipopolysaccharide (LPS) for the last 24 h, were phenotyped for the expression of the co-stimulatory molecules B7·1 and B7·2. In six patients and six controls allogenic mixed leucocyte reaction (AMLR) was performed using mDC and cord blood-derived naive T cells at a DC/T naive ratio of 1 : 200. Proliferation was assessed on day 7 by [3H]-thymidine incorporation assay. Mature DC derived from patients showed, compared with controls, a reduced expression of B7·1 [mean of fluorescence intensity (MFI): 36·2 ± 14·3 versus 72·9 ± 34·5; P = 0·004] and B7·2 (MFI: 122·7 ± 67·5 versus 259·6 ± 154·1; P = 0·02). We did not find differences in the HLA-DR expression (P = 0·07). Moreover, proliferative response of allogenic naive T cells cultured with mDC was impaired in the patients (13471 ± 9917·2 versus 40976 ± 24527·2 cpm, P = 0·04). We also measured IL-10 and IL-12 concentration in the supernatant of DC cultures. Interestingly, we observed in the patients a sevenfold higher level of IL-10 (P = 0·07) and a ninefold lower level of IL-12 (P = 0·01). Our data show a defect in the expression of the co-stimulatory molecules and an impairment of DC priming function, events that might contribute to T1DM pathogenesis. [source]