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R Debets

Publications and source records attributed to R Debets.

27 records · Page 2Linked to original sources
PubMed1996

CD1a+ and CD1a- accessory cells from human bronchoalveolar lavage differ in allostimulatory potential and cytokine production.

Recently, we described the isolation through fluorescent-activated cell sorting (FACS) of low autofluorescent (LAF) cells from human bronchoalveolar lavage (BAL). These LAF cells displayed an immunophenotype comparable with that of dendritic cells (DC), and showed a high potency to stimulate naive T cells. In the study reported here we investigated the capability of LAF cells to produce interleukin-1 (IL-1), IL-6, and tumor necrosis factor alpha (TNF-alpha), and the role of these cytokines in allogeneic T-cell stimulation by LAF cells. Lipopolysaccharide (LPS)-stimulated LAF cells released biologically active IL-1, IL-6, and TNF, and also showed intracellular immunoreactivity for IL-1, IL-6, and TNF-alpha. A neutralizing antibody against IL-1 slightly but statistically significantly (P < 0.05, Wilcoxon's test) inhibited the ability of the LAF cells to stimulate allogeneic T-cell proliferation (89% of stimulation in the absence of the antibody). Neutralizing antibodies against IL-6 and TNF-alpha had no effect. An antibody to granulocyte-macrophage colony-stimulating factor (GM-CSF) also interfered with the accessory function of the LAF cells (79% of stimulation in the absence of the antibody, P < 0.05). We also investigated whether subsets of LAF cells (i.e., positive or negative for CD1a and purified by FACS sorting) differed in T-cell stimulatory capacity and in the ability to produce IL-1, IL-6, TNF-alpha, and S100. CD1a+ LAF cells were positive for and produced S100, CD1a- LAF cells were negative in this respect. The CD1a+ subset exhibited a clearly higher and very strong accessory capability as compared with the CD1a- subset. Despite this, CD1a+ LAF cells were poor producers of IL-1, IL-6, and TNF-alpha. The neutralizing antibody to IL-1, however, inhibited the ability of CD1a+ cells to stimulate allogeneic T-cell proliferation (43% of stimulation in the absence of the antibody, P < 0.01). Anti-IL-6 and alpha-GM-CSF had no effects. CD1a- LAF cells were potent producers of IL-1, IL-6, and TNF-alpha, and antibodies to IL-1, IL-6, and GM-CSF strongly interfered with their weaker accessory capability. In conclusion, two different subsets of LAF cells could be identified on the basis of accessory capability and cytokine profile. CD1a+ LAF cells (S100+; very potent T-cell stimulators, poor cytokine producers) are the "Langerhans cells" of the lung. CD1a- LAF cells (S100-; lower T-cell stimulatory capability, potent producers of IL-1, IL-6, and TNF-alpha) displayed a marker pattern intermediate between that of monocytes and monocyte-derived DC.

Adolescent↗
PubMed1996

Increased expression of interleukin-4 receptors on psoriatic epidermal cells.

Abnormal keratinocyte proliferation and differentiation, the main characteristics of psoriasis, may be induced and maintained by cytokines produced by activated resident and recruited inflammatory cells in lesional skin. As the epidermal cytokine profile is clearly altered in psoriasis and because increased expression of interleukin-4 receptor (IL-4R) has been reported in some epithelial proliferative diseases, we investigated the expression of IL-4R on psoriatic epidermal cells (ECs). The expression of IL-4R on freshly isolated ECs from healthy skin and untreated psoriatic lesions was studied by immunostaining using an IL-4R-specific antibody and by examining their capacity to bind biotinylated recombinant human IL-4 using flow cytometry. The number of IL-4R+ ECs and the number of binding sites per cell were significantly increased on psoriatic ECs as compared with healthy control ECs. Immunostaining confirmed these results, whereby staining was mainly observed in the lower epidermal layers. In addition, an increased IL-4R mRNA expression was also observed in psoriatic epidermis using a digoxigenin-labeled IL-4R RNA probe. In short-term in vitro cultures, lipopolysaccharide/phorbol-myristate-acetate-stimulated and unstimulated psoriatic ECs did not produce any immunoreactive IL-4. The results of this study together with the reported increased expression of IL-4R in epithelial neoplasias suggest an association between overexpression of IL-4R and abnormal keratinocyte activation and proliferation.

Adult↗
PubMed1995

Enhanced production of biologically active interleukin-1 alpha and interleukin-1 beta by psoriatic epidermal cells ex vivo: evidence of increased cytosolic interleukin-1 beta levels and facilitated interleukin-1 release.

The expression of interleukin (IL)-1 is altered in psoriatic lesions. However, little is known about the actual production of IL-1 alpha and IL-1 beta by psoriatic epidermal cells (EC). We monitored IL-1 in the extracellular, the membrane and the intracellular compartment of freshly isolated EC from untreated lesional psoriatic (PP) and normal healthy (NN) skin during non-stimulated short-term cultures, representing a psoriasis model ex vivo. Cytokines were measured using bioassays combined with neutralizing antibodies and enzyme-linked immunosorbent assay in parallel. PP EC released significantly increased amounts of biologically active IL-1 alpha and IL-1 beta in a ratio of 3:1, whereas NN EC only released IL-1 alpha. Also, the release of IL-6, but not of TNF-alpha, by PP EC was significantly increased. Membrane-associated IL-1 activity, analyzed using glutaraldehyde-fixed EC, was low and not unique to PP EC. The cytosol of PP EC contained significantly increased levels of immunoreactive IL-1 beta. Furthermore, PP EC displayed loss of membrane integrity, as determined by trypan blue exclusion and release of cytosolic lactate dehydrogenase. This facilitated release of intracellular IL-1. Depletion of CD45+ cells showed that intraepidermal leukocytes did not contribute to the production of IL-1. Our observations show that resident PP EC express enhanced IL-1 production ex vivo, which is due to an increased cytosolic IL-1 beta content and facilitated IL-1 release. This study provides the first evidence that PP EC can produce bioactive IL-1 beta.

Cells, Cultured↗
PubMed1994

PET studies of patients with partial epilepsy: visual interpretation vs. semi-quantification/quantification.

One of the advantages of PET is to allow for precise regional measurements of radioactive tracers in slices of brain. Furthermore, complex compartment modelling methods have been designed to transform the regional radioactive concentrations into biological units. The question is often raised whether quantification of PET studies is necessary in clinical practice. In epileptology, the regional biochemical changes associated with temporal lobe epilepsy are easily detected by experienced eyes and quantification is not required for diagnosis purposes. By contrast, inter-patient or inter-population comparisons can only be performed if regional measures have been obtained; if the PET method has been previously validated, simple measurements (regional activity) are sufficient and (kinetic) compartmental modelling is not necessary in routine.

Brain↗
PubMedDate not supplied

Carp macrophages and neutrophilic granulocytes secrete an interleukin-1-like factor.

Carp, Cyprinus carpio L, macrophages and neutrophilic granulocytes obtained from pronephros were cultured. Supernatant was harvested after 48 h and tested for interleukin-1 (IL-1) bioactivity. A concentration-dependent stimulation of proliferation was found of carp Ig- lymphocytes as well as of the murine IL-1 dependent D10 (N4) M cell line. A 4 h treatment of cells with phorbol myristate acetate prior to culture gave a two- to fourfold enhancement of the bioactivity in the supernatant. Antibodies raised in sheep against human recombinant IL-1 alpha or IL-1 beta added to the supernatant annulled the IL-1 bioactivity. Western blot analysis of supernatants with sheep or rabbit polyclonal antisera against human IL-1s revealed 22 kDa and 15 kDa protein species. The predominant newly synthesized protein that was immunoprecipitated with these antisera was a 15 kDa molecular species. We conclude that carp macrophages and neutrophilic granulocytes produce an IL-1-like molecule with T-cell proliferating potency that shares structural similarities with mammalian IL-1. This is the first evidence for the IL-1 signal protein in carp immunocompetent cells.

Animals↗
PubMedDate not supplied

Adoptive immuno-gene therapy of cancer with single chain antibody [scFv(Ig)] gene modified T lymphocytes.

Adoptive transfer of antigen-specific T cells has recently shown therapeutic successes in the treatment of viral infections and tumors. T cells specific for the antigen of interest can be generated in vitro, and adoptively transferred back to provide patients with large numbers of immune-competent T cells. Adoptive T cell therapy, however, is a patient-tailored treatment that unfortunately is not universally applicable to treat viral infections and tumors. We and others have demonstrated that the transfer of genes encoding antigen-specific receptors into T cells (i.e., genetic retargeting) represents an attractive alternative to induce antigen-specific immunity. Currently, we evaluate this concept in a clinical protocol to treat patients with metastatic renal cell cancer (RCC) using autologous RCC-specific gene-modified T lymphocytes.

Animals↗