Clones T chez des patients atteints du syndrome hyperéosinophilique idiopathique: Implications pronostiques et thérapeutiques

Interleukin-5 produced by Th2 lymphocytes is involved in the pathogenesis of a number of hypereosinophilic disorders. We and others have identified phenotypically abnormal clonal Th2 cells in peripheral blood of certain patients presenting the idiopathic hypereosinophilic syndrome (IHS). The premalignant nature of the aberrant lymphocytes is suggested by the occasional development of a peripheral T cell lymphoma bearing the same phenotype. In our series of five patients, the T cell clones all bore a CD3- CD4+ phenotype. The production of type-2 cytokines and the proliferation of these cells in response to dendritic cells in vitro were dependent on engagement of CD2 and CD28 molecules and on an IL-2/IL-2R autocrine loop. The high-level spontaneous apoptosis displayed by these cells in vitro was drastically inhibited by IL-2 and IFN-α, suggesting that administration of IFN-α to such patients could favour further expansion and eventual malignant transformation of the T cell clone. The hypereosinophilic syndrome may represent an unexpected application of new immunomodulatory molecules such as CTLA4-Ig and anti-IL-2R-α. © 2001 Éditions scientifiques et médicales Elsevier SAS.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Interferon alpha prevents spontaneous apoptosis of clonal Th2 cells associated with chronic hypereosinophilia

A recent study identified a clonal expansion of CD3(-)CD4(+)cells secreting Th2-type cytokines in 4 patients with chronic hypereosinophilia. Because interferon alpha (IFN-alpha) is used in the therapy of the idiopathic hypereosinophilic syndrome, the effects of this cytokine on the survival of clonal Th2 cells isolated from the blood of 2 patients were determined. First, these cells displayed a high rate of spontaneous apoptosis on culture in cytokine-free medium and were also sensitive to Fas-mediated apoptosis induced by soluble Fas ligand. Addition of IFN-alpha or interleukin-2 (IL-2) to culture medium resulted in significant protection against spontaneous but not Fas-induced apoptosis. Although spontaneous apoptosis of the clonal Th2 cells was clearly associated with down-regulation of both bcl-2 and bcl-x(L) levels, IFN-alpha had no significant effect on the expression of these antiapoptotic proteins, whereas addition of IL-2 resulted in higher levels of bcl-2. On the other hand, IFN-alpha decreased the numbers of cells with disrupted mitochondrial transmembrane potential both during spontaneous apoptosis and after exposure to protoporphyrin IX. Thus, IFN-alpha might promote the survival of clonal Th2 cells, an effect that could be relevant to the therapeutic approach for patients with chronic hypereosinophilia caused by clonal expansion of Th2-type cells. (Blood. 2000;96:4285-4292)Journal ArticleResearch Support, Non-U.S. Gov'tinfo:eu-repo/semantics/publishe

CD40 engagement on endothelial cells promotes tissue factor-dependent procoagulant activity.

The CD40 molecule expressed on endothelial cells has been shown to transduce activation signals resulting in upregulation of adhesion molecules. Herein, we studied the impact of CD40 engagement on the induction of tissue factor (TF)-dependent procoagulant activity (PCA) at the surface of human umbilical vein endothelial cells (HUVECs). First, we found that co-incubation of HUVECs with 3T6 fibroblasts transfected with the CD40L gene (3T6-CD40L) resulted in a clear induction of PCA which was not observed with control untransfected fibroblasts. The specificity of this finding was established by inhibition experiments using monoclonal antibodies (mAbs) blocking CD40 or CD40L. PCA induced by CD40 ligation was TF-related as it was not observed in factor VII-deficient plasma and was associated with the accumulation of TF mRNA. To investigate the role of CD40/CD40L interactions in the induction of endothelial cell PCA by lymphocytes, interferon (IFN)-gamma-stimulated EC were incubated with T cells in the absence or presence of anti-CD40 or anti-CD40L mAb. The 60-70% inhibition of PCA induced by these mAbs but not their isotype-matched control indicated that the CD40 pathway is involved in the induction of PCA resulting from interactions between activated HUVECs and T cells. We conclude that activation signals elicited by CD40 engagement on endothelial cells result in the induction of TF-dependent PCA. The CD40/CD40L pathway might therefore be involved in the development of prothrombic states during diseases associated with endothelial cell and T cell activation.Journal ArticleSCOPUS: ar.jinfo:eu-repo/semantics/publishe

Erratum: Cytokine mRNA quantification by real-time PCR (Journal Immunological Methods (2002) 259 (55-64) PII: S0022175901004896)

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High serum thymus and activation-regulated chemokine levels in the lymphocytic variant of the hypereosinophilic syndrome

The idiopathic hypereosinophilic syndrome is associated with expansion of an IL-5-producing T-cell subset in a subgroup of patients. Identification of such patients is critical to adequate management because there is some evidence that they present an increased risk for development of T-cell lymphoma. Although the T(H)2-like cells often bear an aberrant surface phenotype and can readily be detected with flow cytometry, we now show that lymphocyte phenotyping might be normal in some cases. In contrast, serum thymus and activation-regulated chemokine levels are consistently increased in such patients compared with others with persistent idiopathic hyper-eosinophilia and could therefore represent a useful diagnostic tool.Case ReportsJournal ArticleResearch Support, Non-U.S. Gov'tinfo:eu-repo/semantics/publishe

Cytokine mRNA quantification by real-time PCR.

Real-time PCR represents a new methodology that accurately quantifies nucleic acids. This has been made possible by the use of fluorogenic probes, which are presented in two forms, namely hydrolysis probes (also called TaqMan probes) and hybridisation probes. We decided to apply this methodology to cytokine mRNA quantification and this led us to the development of a protocol that provides an easy way to develop and perform rapidly real-time PCR on a Lightcycler instrument. It was made possible by the use of freely available software that permits a choice of both the hydrolysis probe and the primers. We firstly demonstrated that the reproducibility of the method using hydrolysis probes compares favourably with that obtained with hybridisation probes. We then applied this technique to determine the kinetics of IL-1ra, IL-1beta, IL-5, IL-13, TNF-alpha and IFN-gamma induction upon stimulation of human peripheral blood mononuclear cells (PBMC) by phytohaemagglutinin (PHA). Finally, the method was also used successfully to demonstrate that IFN-alpha induces IL-10 mRNA accumulation in human monocytes.Journal ArticleResearch Support, Non-U.S. Gov'tinfo:eu-repo/semantics/publishe

Mepolizumab as a corticosteroid-sparing agent in lymphocytic variant hypereosinophilic syndrome

Background: Mepolizumab, a monoclonal anti-IL-5 antibody, is an effective corticosteroid-sparing agent for patients with Fip1-like 1/platelet-derived growth factor receptor α fusion (F/P)-negative hypereosinophilic syndrome (HES). Lymphocytic variant hypereosinophilic syndrome (L-HES) is characterized by marked overproduction of IL-5 by dysregulated T cells. Objective: To determine whether patients with L-HES respond to mepolizumab in terms of corticosteroid tapering and eosinophil depletion to the same extent as corticosteroid-responsive F/P-negative patients with HES and a normal T-cell profile. Methods: Patients enrolled in the mepolizumab trial were evaluated for L-HES on the basis of T-cell phenotyping and T-cell receptor gene rearrangement patterns, and their serum thymus-and-activation-regulated chemokine (TARC) levels were measured. Response to treatment was compared in patient subgroups based on results of these analyses. Results: Lymphocytic variant HES was diagnosed in 13 of 63 patients with HES with complete T-cell assessments. The ability to taper corticosteroids on mepolizumab was similar in patients with L-HES and those with a normal T-cell profile, although a lower proportion of patients with L-HES maintained eosinophil levels below 600/μL. Increased serum TARC levels (>1000 pg/mL) had no significant impact on the ability to reduce corticosteroid doses, but a lower proportion of patients with elevated TARC achieved eosinophil control on mepolizumab. Conclusion: Mepolizumab is an effective corticosteroid-sparing agent for patients with L-HES. In some cases however, eosinophil levels remain above 600/μL, suggesting incomplete neutralization of overproduced IL-5 or involvement of other eosinophilopoietic factors. © 2010 American Academy of Allergy, Asthma & Immunology.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Regulatory role of host CD8+ T lymphocytes in experimental graft-versus-host disease across a single major histocompatibility complex class II incompatibility.

BACKGROUND: CD8+ T cells are known to regulate type 2 helper T cell (Th2) alloreactive immune responses but their mode of activation is unclear. We investigated the role of host CD8+ T cells in experimental Th2-type graft-versus-host disease (GVHD) where donor/recipient disparity is restricted to a single major histocompatibility complex (MHC) class II antigen. METHODS: Immunoglobulin (Ig) E serum levels, eosinophilia and lymphoid tissue hyperplasia were compared after injection of bm12 CD4+ T cells in either wild-type or CD8+ T cell-deficient (CD8-/-) C57BL/6 mice. In vitro, we explored effects of the addition of CD8+ T cells from wild-type or IFN-gamma-/- mice in mixed leukocyte cultures prepared with beta2 microglobulin-deficient (beta2m-/-) CD4+ T cells as responders or beta2m dendritic cells as stimulators. RESULTS: HyperIgE resolved after 3 weeks in wild-type hosts whereas it persisted for 6 weeks in CD8-/- hosts. Eosinophil infiltrates in lymph nodes were significantly enhanced in CD8-/- hosts. Increased serum levels of IL-5 and IL-13 in CD8-/- hosts confirmed the enhancement of Th2-type responses in the context of recipient CD8+ T cell deficiency. Hyperplasia of lymph nodes and spleen were similar in both groups, as well as in vivo proliferation of donor CD4+ T cells. In vitro, CD8+ T cell regulation of the alloreactive Th2 response depended on their production of IFN-gamma and did not require expression of beta2m on CD4+ T cells or antigen-presenting cells. CONCLUSIONS: Host CD8+ T cells regulate alloreactive Th2 responses during graft-versus-host disease through an IFN-gamma dependent pathway, independently of the recognition of beta2m-associated MHC class I molecules.Journal ArticleResearch Support, Non-U.S. Gov'tinfo:eu-repo/semantics/publishe

Soluble CD30 binds to CD153 with high affinity and blocks transmembrane signaling by CD30

CD30 is an unusual member of the TNF receptor superfamily with a duplicated segment within its extracellular domain that may function as an additional ligand binding site. The extracellular domain of CD30 is shed from cells and soluble CD30 levels are elevated in certain disease states. Soluble CD30 may bind to its ligand, CD153, with high affinity and block its interaction with membrane-bound CD30. We have generated soluble recombinant forms of CD30 and CD153 in order to characterize their interaction and assess their biological activity. Soluble trimeric CD153 bound to membrane-anchored CD30 with a relatively high affinity (KD=23 nM) and was effective in triggering cell death and TNF- production in the presence of cross-linking antibodies. The affinity and kinetics of the interaction between soluble CD30 and CD153 were determined using the BIAcore biosensor. In contrast to other members of the TNF receptor superfamily, soluble monomeric CD30 bound to itsligand with high affinity (KD=4.5 nM) and prevented the interaction of cellular CD153 with immobilized CD30. Furthermore, soluble CD30 blocked cell death signals generated by cell surface-expressed CD30 effectively. These data suggest that soluble CD30 may have biological functions in vivo