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D De Groote

Publications and source records attributed to D De Groote.

At least 73 records · Page 4Linked to original sources
PubMed1994

Induction of soluble tumor necrosis factor receptor (sTNF-R75) release by HIV adsorption on cultured human monocytes.

Soluble tumor necrosis factor (TNF) receptors were recently detected in the circulation of patients with early HIV-induced disease, at significantly higher levels than in control subjects. They were proposed as markers of disease progression and of the degree of immunodeficiency. We report that adsorption of heat-inactivated HIV-1 LAI to isolated human monocytes triggers the release of both TNF-alpha and its natural specific inhibitor, the soluble TNF receptor (sTNF-R)75, but not that of sTNF-R55. Only limited inhibition of sTNF-R release was obtained in the presence of a fully neutralizing anti-TNF-alpha monoclonal antibody, suggesting that stimulation by TNF-alpha was only partially responsible for sTNF-R release. HIV-1 LAI induced a higher sTNF-R/TNF ratio than lipopolysaccharide, a well-known monocyte activator. Monocytes thus represent a cellular source of sTNF-R that can be detected in the circulation of HIV-infected patients from seroconversion onwards. The release of sTNF-R could be of great significance in the control of HIV infection via the cytokine network and especially TNF-alpha.

HIV Infections↗
PubMed1994

Tumor necrosis factor receptor expression in HIV-1-infected CD4+ T cells.

We investigated whether HIV-1 can regulate tumor necrosis factor receptor (TNFR) expression in SupT-1, a CD4+ T-cell line. The cells were infected with HIV-1 containing 1,000 cpm RT activity, as early as day 3 after infection and all along the culture the supernatant level of core protein p24 was > 250 pg/ml, and on days 6 and 9 after infection, p24 was found in 10% of the cells as determined by indirect immunofluorescence assay. The cells were growing without loss of viability. The study of TNFR expression was based on a microassay for measurement of binding of 125I-TNF alpha to cells, in which free and cell-bound ligand separation was performed by centrifugation through oil. Scatchard analysis of TNF alpha binding on days 6 and 9 after infection revealed a 90% increase in the expression of high-affinity membrane receptors in HIV+SupT-1 culture compared with uninfected cells (mean +/- S.D. = 501 +/- 148.5 vs. 263 +/- 77.8 receptors/cell, n = 9, P < 0.001) with no change in dissociation constants (mean +/- S.D. = 4.36 +/- 1.06 vs. 4.00 +/- 1.12 x 10(-10) M).

CD4-Positive T-Lymphocytes↗
PubMed1994

Elevation of soluble CD23 in serum from patients with blood eosinophilia.

The levels of soluble CD23 (sCD23) were evaluated by a two-site immunoradiometric assay in the sera of 41 patients with eosinophilia-associated disorders and 20 normal subjects. We observed that, in the absence of treatment, sCD23 levels were elevated in patients with eosinophilia-associated Gleich's syndrome, IgA deficiency, T lymphoma or hypereosinophilic syndrome (HES), but not in patients with a parasitic infection. A significant reduction in the sCD23 levels was found after treatment, with a parallel decrease in eosinophil counts and in sCD25 levels, a marker of disease activity in HES. The lack of increase in membrane CD23+ B cells in eosinophilic patients together with the detection of sCD23 in eosinophil supernatants suggest that activated eosinophils present in eosinophilia-associated disorders can release soluble molecules cross-reacting with CD23. In conclusion, our results suggest that eosinophils themselves can represent one cellular source of sCD23. These findings are not only basic but also of clinical interest.

Adrenal Cortex Hormones↗
PubMed1993

Novel method for the measurement of cytokine production by a one-stage procedure.

A new one-step culture-immunoassay procedure is described for testing cytokine production by immunocompetent cells in whole blood (WB) without the need for an isolation step. Briefly, WB samples or distilled water were added to RPMI medium containing specific anti-cytokine peroxidase-labelled monoclonal antibodies and incubated in micro-well plates coated with specific capture monoclonal antibodies, directed against distinct epitopes of the cytokine, and containing dried polyclonal activators (5.625 micrograms LPS + 1.125 micrograms PHA) or dried standards respectively. The optimalisation of the assay is described for an extended measurement range. The best compromise between sensitivity and linearity was obtained with the addition of 50 ng/well for TNF-alpha and IL-6 or 100 ng/well for IFN-gamma of unconjugate antibodies to the corresponding conjugate. The kinetics of individual production of each cytokine in WB of normal healthy donors showed values entering the standard range following incubation times of between 2 and 8 h for TNF-alpha, 2 and 4 h for IL-6, and 4 and 24 h for IFN-gamma. The sensitivity, the precision (intra-assay CVs) and the reproducibility (interassay CVs) of the assays were as follows: 70 pg/ml, < or = 14% and < or = 11% for TNF-alpha; 25 pg/ml, < or = 11% and < or = 16% for IL-6; 25 pg/ml, < or = 19% and < or = 20% for IFN-gamma. The accuracy (% of recovery) of the assays was in the order of 100% and between 40 and 60% in the absence or presence of polyclonal activators, reflecting the occurrence of an active production/consumption mechanism during the activation.

Adult↗
PubMed1993

Alloactivation induced during mixed-lymphocyte reaction provokes release of tumor necrosis factor alpha and interleukin 6 by macrophages and primes them to lipopolysaccharides.

We tested various factors affecting the production of the CKs IL-6 and TNF-alpha during in vitro alloactivation induced by MLR. Different MLR combinations involving familial and unrelated pairs were evaluated. In family studies, MLRs involving pairs of HLA-identical siblings (n = 6) were characterized by IL-6 and TNF-alpha secretion comparable to the one of autologous controls, in marked contrast with HLA-different combinations (n = 6). These displayed a strong and early (day 3) release of both CKs. In combinations of unrelated individuals involving HLA-A, -B, -C-different but -DR, -DQ-identical pairs (n = 3), low CK release was observed. Addition of LPS (1 micrograms/ml) considerably increased production of IL-6 and TNF-alpha. Clear discrimination of MHC class II differences required a 24-hour preculture followed by addition of LPS for 4 hours, a time relationship compatible with a priming phenomenon due to alloactivation. We conclude that MHC class II alloactivation not only provokes IL-6 and TNF-alpha secretion, but also primes macrophages to LPS so that the production of these CKs is markedly increased and occurs much earlier after LPS addition.

Cytokines↗
PubMed1993

Generation of monoclonal antibodies against HILDA/LIF and their use in the quantitative assay of the cytokine.

An adoptive transfer immunization/fusion protocol in mice has been successfully used to raise a series of monoclonal antibodies directed against the Human Interleukin for DA-1a (HILDA)/Leukemia Inhibitory Factor (LIF) cytokine. These antibodies which were raised using recombinant HILDA/LIF purified from conditioned medium of transfected Chinese Hamster Ovary (CHO) cells also react with natural HILDA/LIF from the HSB2 T lymphoma cell line and unglycosylated HILDA/LIF produced in E. coli. They define four separate epitopes, one of which is involved in receptor binding and induction of biological activity. A sensitive sandwich immunoradiometric assay which is linear up to 5 ng/ml HILDA/LIF and can detect as low as 25 pg/ml of the cytokine has been developed.

Animals↗
PubMed1993

Impaired phagocyte responses to lipopolysaccharide in paroxysmal nocturnal hemoglobinuria.

Bone marrow-derived cells from patients suffering from paroxysmal nocturnal hemoglobinuria (PNH) show a defect in the expression of phosphatidylinositol-anchored membrane proteins, including the CD14 molecule. Blocking experiments with anti-CD14 monoclonal antibodies have shown that lipopolysaccharide (LPS)-induced tumor necrosis factor alpha production by monocytes depends on the interaction between CD14 and a complex formed by LPS and LPS-binding protein. We used a whole-blood model to examine the LPS-induced production of tumor necrosis factor alpha and interleukin-6 in PNH patients and healthy volunteers. At low endotoxin concentrations (1 ng/ml), PNH patients displayed a marked defect in the production of both cytokines, whereas at high LPS concentrations (100 ng/ml), cytokine production was similar to that in healthy volunteers. Using flow cytometry, we also studied the expression of the adhesion molecules Mac-1 (CD11b/CD18) and ICAM-1 (CD54) by monocytes and granulocytes after LPS stimulation. Compared with phagocytes from healthy volunteers, CD14-deficient cells showed poor Mac-1 and ICAM-1 upregulation when whole blood was stimulated with LPS (1 ng/ml), whereas their response to higher LPS doses (100 and 1,000 ng/ml) was essentially normal. The importance of the CD14 molecule in the activation of phagocytes by low LPS concentrations was confirmed by the inhibitory effect of an anti-CD14 antibody both in healthy volunteers and in PNH patients. Since these patients produce the soluble form of the CD14 molecule, these data suggest that soluble CD14 could play a role in phagocyte responses to LPS. We conclude that, in whole blood, phagocytes from PNH patients show impaired responsiveness to LPS and this phenomenon is most probably related to their defect in expression of membrane CD14.

Antigens, CD↗
PubMed1993

Soluble CD23 and other receptors (CD4, CD8, CD25, CD71) in serum of patients with chronic lymphocytic leukemia.

We measured the soluble (s) receptors CD23, CD8, CD4, interleukin-2 receptor (IL-2R, CD25), and transferrin receptor (TfR, CD71), in normal serum and in patients with chronic lymphocytic leukemia (CLL) and evaluated them in relation to clinical and biological parameters of the disease, as well as serum immunoglobulin E (IgE). Compared to 31 normal individuals, 42 CLL patients had increased levels of sCD23 (98.4 +/- 127.7 versus 0.9 +/- 0.3 U/ml, p < 0.001), sIL-2R (6080 +/- 7030 versus 1420 +/- 640 pg/ml, p < 0.001), sTfR (12,100 +/- 11,250 versus 5000 +/- 1050 ng/ml, p < 0.001), and sCD8 (510 +/- 191 versus 234 +/- 89 U/ml, p < 0.001), but normal sCD4 levels. Mean sCD23 levels remained normal in patients with non-Hodgkin's lymphoma (other than small lymphocytic), Hodgkin's disease, hairy cell leukemia, acute lymphoblastic leukemia (ALL), acute myelogenous leukemia (AML), chronic myelogenous leukemia (CML), multiple myeloma, or solid tumors. Advancing Rai clinical stage was associated with a progressive elevation of sCD23 (p < 0.001), while sCD8 (p < 0.05), sIL-2R (p < 0.001), and sTfR (p < 0.005) were highest in stage 2 patients. Discriminant analysis confirmed the value of soluble receptor determinations in the clinical evaluation of CLL patients. sCD23 correlated with sIL-2R (p < 0.001) and sTfR (p < 0.05) but not with sCD4 or sCD8, and displayed an inverse relationship with serum IgE (NS) and total gamma-globulin (p < 0.05). sIL-2R correlated with sCD23 (p < 0.001), sTfR (p < 0.001), sCD4 (p < 0.01), and sCD8 (p < 0.01). The lymphocyte count correlated with serum lactate dehydrogenase (LDH) (p < 0.05), sCD23 (p < 0.001) and sIL-2R (p < 0.01) but not sTfR, sCD8, or sCD4. Chemotherapy produced consistent reductions of sCD23 levels in two responding patients. We conclude that: (i) sCD23 is considerably elevated in CLL, correlates with the tumor mass and clinical stage, and could be helpful in monitoring these patients; and (ii) sIL-2R, sCD8, and sTfR levels are less specifically increased and could be influenced by other factors such as immune activation and erythropoiesis.

Aged↗
PubMed1992

Intraoperative cytokines production during orthotopic liver transplantation.

In summary, we established that a significant production of the monokines interleukin-6, tumor necrosis factor apha, and interleukin-1 occurred during orthotopic liver transplantation whereas the lymphokines interferon gamma and interleukin-2 were not detected. Levels of interleukin-6 reached their maximum values before and especially at the end of the anhepatic phase. They remained high after the anhepatic phase, i. e. after reperfusion of the new livers. Tumor necrosis factor alpha and interleukin-1 reached their maximum values after the anhepatic phase. Not only were interleukin-6, tumor necrosis factor alpha, and interleukin-1 present in the serum but they could also be detected in the bile produced by these new livers. Mechanisms of monokine production during orthotopic liver transplantation is multifactorial in origin and further studies will have to evaluate the relative contribution of the various factors involved. The possibility of an association between peroperative monokines and transplant outcome and their potential clinical implication will have to be elucidated.

Cytokines↗
PubMed1992

Immunochemical characterization of antigenic domains on human IL-2: spatially distinct epitopes are associated with binding to the p55 and p70 subunits of IL-2 receptor.

We have isolated and characterized 8 mAb against human rIL-2. All recognize nonglycosylated rIL-2 in liquid phase with similar affinities (Kd approximately 1 nM). Based on the epitopes of the IL-2 molecule that they recognize and their pattern of reactivity against glycosylated and non-glycosylated IL-2, they have been classified into four groups. The first group of anti-IL-2 mAb (2C4, 19B11 and 12C2) inhibits IL-2 binding to p70 IL-2R, while the second one (16F11, 18E1 and 2A4) prevents its binding to p55 IL-2R. These two groups neutralize IL-2 activity in a T cell proliferation assay equally well, due to their similar inhibition of IL-2 binding to high affinity IL-2R. Two mAb, 3H9 and 17F4, recognize separate epitopes on IL-2 molecule, are poor inhibitors of IL-2 binding, and they are inefficient in the neutralization of its biological activity; they have been assigned to the third and fourth groups, respectively. These results show that mAb from the first and second group recognize two epitopes of the human IL-2 molecule which probably overlap the p70 IL-2R and p55 IL-2R binding sites, respectively. In addition, these areas together form the high affinity IL-2R binding site. The two mAb from the third and fourth group recognized epitopes of IL-2 not directly involved in IL-2 binding to its receptor. All eight mAb anti-human IL-2 recognize murine IL-2 and with the exception of one, 17F4 mAb are also able to neutralize it in a T cell proliferation assay. The relationship between the structure and the function of the IL-2 molecule is discussed.

Animals↗
PubMed1992

Direct stimulation of cytokines (IL-1 beta, TNF-alpha, IL-6, IL-2, IFN-gamma and GM-CSF) in whole blood: II. Application to rheumatoid arthritis and osteoarthritis.

Rheumatoid arthritis (RA) is an immune disease in which the pathological immune reaction is thought to be initiated by the presentation of an (auto) antigen or superantigen by MHC class II positive cells to CD4 T cells. These successive immunological events can be studied by the cytokines produced at the different stages. Cytokine secretion by stimulated cells in autologous diluted whole blood has allowed the study of the immune profile characteristic of rheumatoid arthritis. The pattern of RA patient whole blood cells cultured in autologous blood is characterized by hyperactivity of the mononuclear cells with high secretion of IL-1 beta, TNF-alpha and IL-6 and low production of IFN-gamma, in comparison with the normal (N) and osteoarthrosis (OA) populations. The IL-2 secretion pattern is unique, arising from production followed by consumption. This production-consumption turnover is the most elevated in the RA group. The T cells are indeed activated in rheumatoid arthritis but regulatory events suppress some of their functions. A correlation was found between the inflammatory proteins and mediators of cellular immunity and macrophagic function: IL-1 beta and the sedimentation rate; IL-6 and fibrinogen; TNF-alpha and the number of blood monocytes. The secretion of OA-stimulated whole blood cells was similar to RA for two monokines (overproduction of TNF-alpha and IL-6) and different for IL-1 beta, not different from normal in OA. Stimulated whole blood cell cytokine secretion profile from RA and OA groups, was the same as previously observed in synovial fluid.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Direct stimulation of cytokines (IL-1 beta, TNF-alpha, IL-6, IL-2, IFN-gamma and GM-CSF) in whole blood. I. Comparison with isolated PBMC stimulation.

Production of interleukin 1 beta (IL-1 beta), interleukin 6 (IL-6), tumor necrosis factor alpha (TNF-alpha), interleukin 2 (IL-2), interferon gamma (IFN-gamma) and granulocyte-macrophage colony-stimulating factor (GM-CSF) after stimulation by lipopolysaccharide (LPS) and phytohemagglutinin (PHA) was studied in 1/10 diluted whole blood (WB) culture and in peripheral blood mononuclear cell (PBMC) culture. Cytokines IL-1 beta, TNF-alpha and IL-6 are preferentially stimulated by LPS whereas IL-2, IFN-gamma and GM-CSF are stimulated by PHA. Combination of 5 micrograms/ml PHA and 25 micrograms/ml LPS gave the most reliable production of the six cytokines studied. IL-1 beta, TNF-alpha and IL-6 represent a homogeneous group of early-produced cytokines positively correlated among themselves and with the number of monocytes in the culture (LeuM3). Furthermore, IL-1 beta was negatively correlated with the number of T8 lymphocytes. IL-2, IFN-gamma and GM-CSF represent a group of late-produced cytokines. Kinetics and production levels of IL-6 and GM-CSF are similar in WB and PBMC cultures. In contrast, production levels of TNF-alpha and IFN-gamma are higher in WB than in PBMC whereas production levels of IL-6 and IL-2 are lower in WB than in PBMC. Individual variation in responses to PHA + LPS was always higher in PBMC cultures than in WB cultures. The capacity of cytokine production in relation to the number of mononuclear cells is higher in WB, or in PBMC having the same mononuclear cell concentration as WB, than in conventional cultures of concentrated PBMC (10(6)/ml). Because it mimics the natural environment, diluted WB culture may be the most appropriate milieu in which to study cytokine production in vitro.

Adult↗
PubMed1992

Metabolic and respiratory changes after cholecystectomy performed via laparotomy or laparoscopy.

We have compared metabolic and respiratory changes after laparoscopic cholecystectomy (n = 15) with those after open cholecystectomy (n = 15). The durations of postoperative i.v. therapy, fasting and hospital stay were significantly shorter in the laparoscopy group. During the first and second days after operation, analgesic consumption but not pain scores (visual analogue scale) were significantly smaller after laparoscopy, while vital capacity, forced expiratory volume in 1 s, and PaO2 were significantly greater. The metabolic and acute phase responses (glucose, leucocytosis, C-reactive protein) were less after laparoscopy compared with laparotomy. Although plasma cortisol and catecholamine concentrations were not significantly different between the two groups, after surgery interleukin-6 concentrations were less in the laparoscopy group.

Acute-Phase Reaction↗
PubMed1992

Cytokine serum level during severe sepsis in human IL-6 as a marker of severity.

Forty critically ill surgical patients with documented infections were studied during their stay in an intensive care unit. Among these patients, 19 developed septic shock and 16 died, 9 of them from septic shock. Interleukin 1 beta (IL-1 beta), tumor necrosis factor (TNF alpha), and interleukin 6 (IL-6) were measured each day and every 1 or 2 hours when septic shock occurred. Although IL-1 beta was never found, TNF alpha was most often observed in the serum at a level under 100 pg/mL except during septic shock. During these acute episodes TNF alpha level reached several hundred pg/mL, but only for a few hours. In contrast, IL-6 was always increased in the serum of acutely ill patients (peak to 500,000 pg/mL). There was a direct correlation between IL-6 peak serum level and TNF alpha peak serum level during septic shock and between IL-6 serum level and temperature or C-reactive protein serum level. Moreover, IL-6 correlated well with APACHE II score, and the mortality rate increased significantly in the group of patients who presented with IL-6 serum level above 1000 pg/mL. Thus, IL-6 appears to be a good marker of severity during bacterial infection.

Adult↗
PubMed1992

Immunomodulatory properties of cyclic hexapeptide oxytocin antagonists.

The thymic repertoire of neuroendocrine 'self' antigens has been previously described on the basis of the intrathymic expression of neurohypophysial (NHP)- and tachykinin-related peptide signals and receptors. According to that model, the cryptocrine signalling between thymic epithelial/nurse cells and thymocytes through NHP-related signals and receptors constitutes one accessory pathway in the process of T-cell differentiation and/or activation. A pharmacological manipulation of that novel type of cell-to-cell signalling was tested by the investigation of the immunomodulatory properties of novel cyclic hexapeptide oxytocin (OT) antagonists (MSD Research Laboratories). These compounds were found to significantly inhibit the productions of cytokines (mainly IL-1 beta and IL-6) elicited by anti-CD3 treatment of human whole blood cell cultures. Cytokine productions were more significantly reduced by OT antagonists in whole blood cell cultures derived from female volunteers than in those obtained from male donors, suggesting an influence of the gonadal steroid environment on the expression of NHP peptide receptors by immune cells. These observations support the concept of novel immunomodulating approaches through immune-specific neuropeptide antagonists, as well as the pharmacological value of such strategies in selective immunotherapy.

Adjuvants, Immunologic↗
PubMed1991

Colocalization of immunoreactive oxytocin, vasopressin and interleukin-1 in human thymic epithelial neuroendocrine cells.

Monoclonal antibodies to oxytocin (OT) and vasopressin (VP) revealed some positively staining stromal cells in the subcapsular cortex and in the medulla of the human thymus. We further demonstrated that these cells are a subset of epithelial endocrine cells and also contain immunoreactive interleukin-1 together with the neuropeptides. In addition, the thymic cells stained by monoclonal antibodies directed to the cyclic part of oxytocin or vasopressin also contained some immunoreactive neurophysins. These data support the concept of intrathymic synthesis of neurohypophyseal-like peptides fitting the hypothalamic model. However, we observed that, contrary to the situation in the brain, OT- and VP-like peptides colocalized in the same thymic cells. Furthermore, one monoclonal antibody, specific for the tail part of oxytocin, did not label thymic cells. Therefore, thymic neuropeptide(s) could be related to, but distinct from, authentic OT and VP. These observations suggest some molecular differences between hypothalamic and thymic oxytocin biosynthetic pathways which need to be further investigated.

Antibodies, Monoclonal↗
PubMed1991

Prevention of human TNF-induced cutaneous Shwartzmann reaction and acute mortality in mice treated with anti-human TNF monoclonal antibodies.

We studied monoclonal antibodies (MoAbs) directed against human tumour necrosis factor (TNF) for their capacity to prevent toxic or lethal effects of TNF. Two experimental models involving recombinant human TNF (rhTNF) in mice were used: the Shwartzmann reaction, and the lethality after D-galactosamine sensitization. Two MoAbs were found to be protective in both models. These MoAbs prevented mortality when given 6 h, 4 h, or 15 min before rhTNF injection but were not effective if given after TNF. In addition, our results point out that in vitro binding and even neutralizing capacities of anti-hTNF MoAbs do not necessarily reflect their protective efficacy in vivo. Therefore, the models studied here might be useful to evaluate anti-h TNF MoAbs before clinical use.

Animals↗