Biomedical subjects
D Emilie
Publications and source records attributed to D Emilie.
[Activation of human B lymphocytes by a particulate antigen].
A specific IgM antibody response toward the trinitrophenol (TNP) hapten can be induced in mononuclear blood cell suspensions upon culture with a particulate antigen: polyacrylamide beads conjugated with the TNP hapten (TNP-PAA). The response, and its specificity, are demonstrated by an increase in the number of TNP binding B lymphocytes (specific rosette forming cells), by the appearance of cells producing anti-TNP antibody at a high rate (haemolytic plaques), (ELISA test). The anti-TNP response requires monocytes, the role of which is to produce interleukin-1 (IL-1) and T lymphocytes (belonging to the T4 helper subset) the role of which is to produce interleukins (the characterization of which is under study). We propose a model or B cell activation based on the following signals: an early specific signal, provided by the particulate antigen; several non specific signals, provided by T derived interleukins. The anti-TNP response is negatively regulated by monocytes, the functional states of which can be modified in certain situations (autoimmunity, aging) or influenced by glucocorticoids. Suppressor T lymphocytes of this response (not exclusively of the T8 phenotype) can be induced and this can allow the evaluation of T suppressor cell function. This was used in adult idiopathic thrombocytopenic purpura treated with high doses of intra-venous gammaglobulins.
Inhibition of in vitro immunosuppressive effects of glucocorticosteroids by a competitive antagonist RU-486.
The 19-nor-steroid RU-486 is an antagonist of glucocorticosteroids acting competitively at the receptor level. Pharmacological and endocrinological studies have already shown that RU-486 is able to reverse glucocorticosteroid effects. The present study shows that RU-486 can counteract the inhibitory effect of glucocorticosteroids in two highly corticoid-sensitive in vitro immune responses: murine in vitro antibody response and human autologous mixed lymphocyte reaction.
Effect of hydrocortisone on the in vitro human antibody response: interaction with monocytes and prostaglandins.
The specific plaque-forming cell response induced by trinitrophenyl polyacrylamide beads in cultures of nonadherent human peripheral blood mononuclear cells (PBM) is resistant to the inhibitory effect of hydrocortisone (HC). Previous results showed that low concentrations (up to 10(-7 M) of HC inhibit the same response in cultures of unfractionated human PBM. It is shown that the addition of 5-10% monocytes to nonadherent PBM renders their response HC-sensitive. One mechanism of the interaction between HC and monocytes is the potentiation of prostaglandin E2-mediated suppression by HC, which can be demonstrated in vitro and after in vivo administration of HC. However, interaction with a non-prostaglandin-mediated suppression by monocytes should be involved, particularly with high (10(-6) M) concentrations of HC.
Prostaglandin E2 regulation of human specific B-cell response: interaction with a monocyte product.
The effect of exogeneous prostaglandin E2 (PGE2) on the specific plaque-forming cell (PFC) response in cultures of non-adherent human peripheral blood mononuclear cells (PBM) was tested. When added on Day 2 of the cultures PGE2 inhibits the induction of the PFC response, and the maximum inhibition (50%) is obtained with 300 nM PGE2. When PBM are cultured during the first 24 hr with the same concentration of PGE2 their PFC response is enhanced and the target of this enhancement is a T cell. When PGE2 is added on Day 0 it does not affect the response, probably because of a balance between these two opposing effects. However, in the latter conditions a prostaglandin-free monocyte supernatant can render PGE2 suppressive. The monocyte supernatant acts by inhibiting the stimulatory effect after the interaction between PGE2 and T cells. Thus the effect of PGE2 depends on its time of action and on the concomitant production of a nondialyzable factor by monocytes.
[Acute post-streptococcal glomerulonephritis during acute articular rheumatism].
Explore the source record for details and available documents.
Cytokines in HIV infection.
Human immunodeficiency virus infection leads to a deregulated production of a number of cytokines. Some of them (IL-1, IL-6, TNF-alpha, interferon-gamma) are produced in increased amounts in vivo, whereas the production of IL-2 is decreased. This latter abnormality plays a pivotal role in the establishment of the immunodeficiency. Some cytokines (IL-1, IL-6, TNF-alpha) stimulate the in vitro replication of HIV, whereas others (mainly the interferons) inhibit it. The effect of cytokines in vivo in the spreading of HIV remains, however, largely unknown. Cytokines may also be involved in the development of many clinical manifestations associated with HIV infection. IL-1, IL-6 and TNF-alpha may play a role in tissue damages associated with opportunistic infections, in HIV-related encephalopathy and in cachexia. Cytokines, mainly IL-6, IL-10 and IL-13, may stimulate the growth of malignant cells during Kaposi sarcoma or lymphomas. Better knowledge of the role of cytokines during HIV infection should allow new therapeutic approaches based on the use of either recombinant cytokines or specific antagonists, with the aim of limiting both HIV spreading and the clinical manifestations of this infection.
Anti-HIV neutralizing antibodies do not inhibit HIV-induced cell fusion in vitro.
Explore the source record for details and available documents.
Cytokines from lymphoid organs of HIV-infected patients: production and role in the immune disequilibrium of the disease.
Explore the source record for details and available documents.
[Immunopathology of cytomegalovirus pneumopathy and allograft rejection after lung transplantation].
Explore the source record for details and available documents.
IL-6 mRNA expression in CD25 positive malignant lymphomas.
We recently demonstrated that IL-2 is produced by reactive T cells in CD25-positive malignant lymphomas (ML). Using in situ hybridization, we investigated IL-6 mRNA expression in these CD25-positive ML. The ML tested included 9 anaplastic large cell lymphomas and 3 B-diffuse large cell lymphomas. Five CD25-negative ML were studied as controls. We show that IL-6 producing cells are present in all these ML. The density of positive cells was heterogeneous from case to case. However 3 cases of CD25-positive ML showed a dramatically higher density of IL-6 producing cells (70, 50, 43 producing cells per 10,000 cells, respectively) as compared to the other 9 cases of CD25-positive ML (mean 6.03 +/- 2.1 per 10,000). Morphological and topographical data suggested that several types of cells including fibroblasts, lymphocytes, macrophages and endothelial cells may synthesize IL-6. A combination of immunohistochemistry and in situ hybridization showed that reactive T cells and endothelial cells express the IL-6 gene whereas CD30-positive ML cells do not express this gene. Previous studies showed that IL-6 was capable to induce IL-2 receptor expression as well as production of IL-2 and stimulation of lymphomatous cells growth. Our present results indicate that the paracrine production of this cytokine may play a role in the proliferation of malignant lymphomas.
In vivo expression of IL-1 beta and IL-6 genes during viral infections in human.
Macrophage infiltration is a constant feature of human virus-infected tissues. However, the in situ functional status of these cells remains undetermined. In order to document an activation of macrophages in virus-infected tissues, the expression of IL-1 beta and IL-6 genes was analyzed using in situ hybridization. Several tissues were studied, as well as infections induced by different viruses: lymph nodes infected by HIV-1 (9 cases) or EBV (one case), lungs infected by CMV (5 cases) or adenovirus (1 case), livers infected by HBV, either chronically (2 cases) or acutely (7 cases presenting a fulminant hepatitis). With the exception of fulminant HBV hepatitis, IL-1 beta and IL-6 genes were expressed in all cases. IL-1 beta and IL-6 genes were usually coordinately regulated, as cells containing IL-1 beta or IL-6 mRNA were present in identical amounts and displayed a similar distribution. Analysis of the location and the morphology of monokine gene-expressing cells indicated that both small macrophages and endothelial cells expressed IL-1 beta and IL-6 genes. However, neither tingible body macrophages present in lymph node follicles nor Kupffer cells expressed these genes at a detectable level. Infected cells themselves were also negative for monokine gene expression. These findings indicate that expression of IL-1 beta and IL-6 genes by reactive cells may play a role in viral spreading limitation as well as virus-induced tissue damage.
Spontaneous production of interleukin-10 by B lymphocytes and monocytes in systemic lupus erythematosus.
Interleukin-10 (IL-10) production by B lymphocytes has previously been demonstrated for malignant cells and for in vitro activated normal B cells. Spontaneous in vivo production of IL-10 by normal B lymphocytes has only been demonstrated in mice, in which autoreactive Ly 1 + B cells are involved. In the present study, spontaneous expression of the IL-10 gene by peripheral blood mononuclear cells was investigated in systemic lupus erythematosus (SLE), a human disease involving autoreactive B cells. Of the 47 SLE patients tested by coupled reverse transcriptase-polymerase chain reaction, 34 scored positive, contrasting with only 1 positive out of 34 normal subjects (p < 0.001). Spontaneous in vitro production of IL-10 by PBMC, determined using an ELISA assay, was 33 times higher in SLE than in controls (2623 +/- 728 pg/ml vs 79.3 +/- 34.5 pg/ml, respectively) (p < 0.001). The level of production of IL-10 in SLE was unrelated to either clinical or biological markers of disease activity. Among PBMC, monocytes and B lymphocytes both contributed to IL-10 production, whereas T cells did not. IL-10 overproduction in SLE suggests that this Th2-type interleukin plays a role in the production of autoantibodies through pathways involving both paracrine production by monocytes and autocrine IL-10 production by autoreactive B cells.
Interleukin-6 overproduction by cultured thymic epithelial cells from patients with myasthenia gravis is potentially involved in thymic hyperplasia.
Most patients with Myasthenia Gravis (MG) present a thymic hyperplasia characterized by the presence of lymphoid follicles. The acetylcholine receptor autoantigen, as well as autoantigen specific activated T and B cells found in the thymus, strongly suggest that auto-sensitization could take place in this organ. Since IL-6 is involved in T and B cell growth and differentiation, we thought that abnormal IL-6 expression by thymic epithelial cells (TEC) could be related to thymic hyperplasia in MG. In this paper, IL-6 protein and gene expression by cultured TEC from patients with MG were examined. TEC from patients presented a dramatic IL-6 hyperproduction phenotype as compared to controls when stimulated by exogenous signals such as LPS and cytokines (IL-1 beta, TNF-alpha) alone or in combination. Moreover, we observed a similar effect with a physiological signal such as the syngeneic lympho-epithelial cell contact. Autologous thymocytes stimulated normal and MG TEC IL-6 production in a time- and dose- dependent way, and with a higher magnitude in MG TEC compared to controls. In all stimulation conditions, induction of IL-6 production required protein synthesis and was associated with increased IL-6 mRNA level expression as assessed by computer-aided quantification after in situ mRNA hybridization. In addition, recombinant IL-6 induced in vitro growth of TEC, demonstrating that IL-6 is a possible autocrine growth factor for these cells. This deregulated IL-6 production as well as the ability of TEC to use it as a growth factor may be of pathophysiological relevance in MG. It provides an explanation for morphological changes of the thymus and may have a key role in initiation, exacerbation and ongoing of the autoimmune response in MG. Therefore this study extends our current understanding of the molecular pathophysiology of MG.
Quantification of cytokine gene expression by competitive PCR using a colorimetric assay.
Competitive reverse transcription-polymerase chain reaction (RT-PCR) is a new technique allowing quantification of cytokine gene expression from either experimental or clinical samples. In this assay, a time-consuming step is the quantification of amplified products. To improve this step, we set up a colorimetric assay in which the amplified product from either the cDNA or the competitor can be reliably quantified. Using this approach, which can be completely automatized, up to 320 PCR products can be quantified each day. In this report, we describe the quantification of IL-10 mRNA molecules as compared to that of beta-actin mRNA molecules. The sensitivity of the quantification was 7.7 x 10(7) molecules for the amplified beta-actin cDNA and the amplified IL-10 cDNA, corresponding to approximately 9.6 pg amplified beta-actin cDNA and 11 pg amplified IL-10 cDNA, respectively. The intra-assay variation coefficient was < 12%. This technique can be readily extended to all cytokines, and it thus allows routine monitoring of cytokine gene expression, either from experimental samples or from clinical trials.
[The production of IL-10 in HIV-positive patients with lymphoma].
Explore the source record for details and available documents.