Respiratory Syncytial Virus Infects Regulatory B Cells in Human Neonates via Chemokine Receptor CX3CR1 and Promotes Lung Disease Severity.

Respiratory syncytial virus (RSV) is the major cause of lower respiratory tract infections in infants and is characterized by pulmonary infiltration of B cells in fatal cases. We analyzed the B cell compartment in human newborns and identified a population of neonatal regulatory B lymphocytes (nBreg cells) that produced interleukin 10 (IL-10) in response to RSV infection. The polyreactive B cell receptor of nBreg cells interacted with RSV protein F and induced upregulation of chemokine receptor CX3CR1. CX3CR1 interacted with RSV glycoprotein G, leading to nBreg cell infection and IL-10 production that dampened T helper 1 (Th1) cytokine production. In the respiratory tract of neonates with severe RSV-induced acute bronchiolitis, RSV-infected nBreg cell frequencies correlated with increased viral load and decreased blood memory Th1 cell frequencies. Thus, the frequency of nBreg cells is predictive of the severity of acute bronchiolitis disease and nBreg cell activity may constitute an early-life host response that favors microbial pathogenesis.

Phagocyte-specific S100A8/A9 is upregulated in primary Sjögren's syndrome and triggers the secretion of pro-inflammatory cytokines in vitro.

OBJECTIVES: To determine the role of S100A8/A9 in the pathogenesis of primary Sjögren's syndrome (pSS). METHODS: The serum levels of S100A8/A9 were determined in pSS patients and healthy controls by ELISA. The expression of S100A8/A9 in salivary glands was assessed by immunohistochemistry. The phenotype of S100A8+ and S100A9+ cells was identified using double immunofluorescence. The effects of S100A8/A9 on cytokine production by peripheral blood mononuclear cells (PBMCs) from pSS patients were determined in vitro by flow cytometry. The effects of pro-inflammatory cytokines on S100A8/A9 secretion were additionally investigated in vitro by ELISA in PBMCs from pSS patients and control subjects. RESULTS: Serum levels of S100A8/A9 were significantly increased in pSS patients compared to healthy controls. The tissular expression of S100A8 and S100A9, identified in professional phagocytes (neutrophils, monocytes and plasmacytoid dendritic cells), was increased in the salivary glands of pSS patients and correlated with focus score. In vitro, recombinant S100A8/A9 increased the production of IL-1ß, IL-6, TNF-α, IFN-γ, IL-10, IL-17A and IL-22 by PBMCs. The S100A8/A9-induced increase in TNF-α production in pSS patients was significant relative to controls. Furthermore, IL-1ß, TNF-α, IL-6, and IL-17A stimulated release of S100A8/A9 from PBMCs in pSS patients. CONCLUSIONS: S100A8/A9 is increased in pSS patients contributing to the in vitro increased production of pro-inflammatory cytokines. As such, S100A8/A9 in concert with other cytokines might contribute to the pathogenesis of pSS.

Potential involvement of the IL-33-ST2 axis in the pathogenesis of primary Sjogren's syndrome.

OBJECTIVES: To investigate the role of the interleukin (IL)-33-ST2 axis in the pathophysiology of primary Sjögren's syndrome (pSS). METHODS: Serum levels of IL-33 and sST2 were determined by ELISA. The expression of IL-33 and ST2 was investigated in salivary glands (SG) by immunohistochemistry. PBMC were isolated and stimulated with IL-33, IL-12 and IL-23 and the cytokine profile response was examined by flow cytometry. Intracellular cytokine detection of IFNγ and IL-17 was performed by flow cytometry. RESULTS: Serum IL-33 and sST2 levels were increased in pSS patients compared with controls and patients with systemic lupus erythematosus. Expression of IL-33 was upregulated in SG with Chisholm scores of 2 and 3 of pSS patients but comparable with controls for SG with Chisholm score of 4. ST2 expression in SG was downregulated in pSS patients. IL-33 at different concentrations did not increase the secretion of pro-inflammatory cytokines but acted synergistically with IL-12 and IL-23 to promote IFNγ production. NK and NKT cells were identified as main producers of IFNγ in vitro and were found in SG of pSS patients. CONCLUSIONS: IL-33 is released in pSS, and acts with IL-12 and IL-23 to favour the secretion of IFNγ by NK and NKT cells.

Antibody deficiency due to a missense mutation in CD19 demonstrates the importance of the conserved tryptophan 41 in immunoglobulin superfamily domain formation.

Immunoglobulin superfamily (IgSF) domains are conserved structures present in many proteins in eukaryotes and prokaryotes. These domains are well-capable of facilitating sequence variation, which is most clearly illustrated by the variable regions in immunoglobulins (Igs) and T cell receptors (TRs). We studied an antibody-deficient patient suffering from recurrent respiratory infections and with impaired antibody responses to vaccinations. Patient's B cells showed impaired Ca(2+) influx upon stimulation with anti-IgM and lacked detectable CD19 membrane expression. CD19 sequence analysis revealed a homozygous missense mutation resulting in a tryptophan to cystein (W52C) amino acid change. The affected tryptophan is CONSERVED-TRP 41 located on the C-strand of the first extracellular IgSF domain of CD19 and was found to be highly conserved, not only in mammalian CD19 proteins, but in nearly all characterized IgSF domains. Furthermore, the tryptophan is present in all variable domains in Ig and TR and was not mutated in 117 Ig class-switched transcripts of B cells from controls, despite an overall 10% amino acid change frequency. In vitro complementation studies and CD19 western blotting of patient's B cells demonstrated that the mutated protein remained immaturely glycosylated. This first missense mutation resulting in a CD19 deficiency demonstrates the crucial role of a highly conserved tryptophan in proper folding or stability of IgSF domains.

IL-12Rß1 deficiency and disseminated Mycobacterium tilburgii disease.

Mycobacterium tilburgii rarely causes disseminated disease. We describe a case of M. tilburgii infection in an otherwise healthy 33-year-old woman, who was found to carry bi-allelic mutations of the gene encoding the ß1 chain of the IL-12 receptor.

Eosinophils affect functions of in vitro-activated human CD3-CD4+ T cells.

BACKGROUND: The recent development of eosinophil-targeting agents has raised enthusiasm for management of patients with hypereosinophilic syndromes. Roughly half of anti-IL-5-treated patients with corticosteroid-responsive lymphocytic (L-HES) and idiopathic disease variants can be tapered off corticosteroids. Potential consequences of corticosteroid-withdrawal on clonal expansion of pre-malignant CD3⁻CD4⁺ T-cells associated with L-HES are a subject of concern. Indeed, corticosteroid treatment inhibits T-cell activation and may lower blood CD3⁻CD4⁺ cell counts. On the other hand, previous studies have shown that eosinophils support CD4 T-cell activation, suggesting that targeted eosinophil depletion may negatively regulate these cells. OBJECTIVES: Effects of eosinophils on CD4 T-cell activation in vitro were investigated as an indirect means of exploring whether treatment-induced eosinophil depletion may affect pathogenic T-cells driving L-HES. METHODS: Helper (CD4) T-cells and CD3⁻CD4⁺ cells from healthy controls and L-HES patients, respectively, were cultured in vitro in presence of anti-CD3/CD28 or dendritic cells. Effects of eosinophils on T-cell proliferation and cytokine production were investigated. RESULTS: Eosinophils enhanced CD3-driven proliferation of CD4 T-cells from healthy subjects in vitro, while inhibiting TCR-independent proliferation and IL-5 production by CD3⁻CD4⁺ T-cells. CONCLUSIONS: While this study confirms previous work showing that eosinophils support activation of normal helper T-cells, our in vitro findings with CD3⁻CD4⁺ T-cells suggest that eosinophil-depletion may favor activation and expansion of this pathogenic lymphocyte subset. With the ongoing development of eosinophil-targeted therapy for various eosinophilic conditions, the indirect consequences of treatment on the underlying immune mechanisms of disease should be investigated in detail in the setting of translational research programs.

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.

CD3-CD4+ Lymphocytic Variant Hypereosinophilic Syndrome: Diagnostic Tools Revisited.

BACKGROUND: Identification of patients with lymphocytic variant hypereosinophilic syndrome (L-HES) is challenging, and has important prognostic and therapeutic implications. OBJECTIVE: This study was undertaken to assess diagnostic tools for L-HES and to develop evidence-based diagnostic recommendations. METHODS: Biomarkers of T-cell-driven disease were compared between patients with L-HES versus idiopathic HES (I-HES) variants. Those performed routinely (serum immunoglobulin levels, T-cell phenotyping, T-cell receptor [TCR] gene rearrangement patterns) were collected from medical files, whereas others were prospectively assessed on stored blood samples (serum CCL17/thymus and activation regulated chemokine [TARC] levels, in vitro cytokine production). RESULTS: This study included 48 patients with I-HES and 20 with L-HES associated with a CD3-CD4+ T-cell subset, including 7 with less than 5% aberrant cells. Neither increased serum immunoglobulin levels nor clonal TCR gene rearrangements were sufficiently sensitive or specific for L-HES. In contrast, systematically enhanced expression of the T-cell surface antigens CD2, CD5, CD45RO, and CD95 by these cells allowed for accurate detection by flow cytometry. Serum CCL17/TARC levels were significantly higher in patients with L-HES compared with those with I-HES, and a threshold of 3000 pg/mL allowed for detection of all subjects with L-HES with 75% specificity. Quantification of intracytoplasmic cytokine production by flow cytometry is the most reliable method for detection of enhanced type 2 cytokine expression, most notably for IL-4 and IL-13. CONCLUSION: Adapting the standard of procedure for T-cell phenotyping in patients with unexplained hypereosinophilia is currently the most reliable means of identifying those with CD3-CD4+ L-HES.

Eosinophilia Associated With CD3-CD4+ T Cells: Characterization and Outcome of a Single-Center Cohort of 26 Patients.

Background: Lymphocytic variant hypereosinophilic syndrome is characterized by marked over-production of eosinophilopoietic factor(s) by dysregulated T cells leading to eosinophil expansion. In most cases, these T cells are clonal and express a CD3-CD4+ phenotype. As this is a rare disorder, presenting manifestations, disease course, treatment responses, and outcome are not well-characterized. Materials and Methods: In this retrospective single-center observational study, we reviewed medical files of all patients with persistent hypereosinophilia seen between 1994 and 2019 in whom CD3-CD4+ T cells were detected. Data collection included clinical and biological findings at presentation, treatment responses, disease course, and serial CD3-CD4+ T cell counts. Results: Our cohort comprises 26 patients, including 2 with hypereosinophilia of undetermined significance. All 24 symptomatic patients had cutaneous lesions and/or angioedema, and fasciitis was present in several cases. The aberrant T cell subset represented 2% or less total lymphocytes in 11 subjects. TCR gene rearrangement patterns on whole blood were polyclonal in these cases, while they all had serum CCL17/TARC levels above 1,500 pg/ml. Disease manifestations were mild and did not require maintenance therapy in roughly one third of the cohort, while two thirds required long-term oral corticosteroids and/or second-line agents. Among these, interferon-alpha was the most effective treatment option with a response observed in 8/8 patients, one of whom was cured of disease. Treatment had to be interrupted in most cases however due to poor tolerance and/or development of secondary resistance. Anti-interleukin-5 antibodies reduced blood eosinophilia in 5/5 patients, but clinical responses were disappointing. A sub-group of 5 patients had severe treatment-refractory disease, and experienced significant disease- and treatment-related morbidity and mortality, including progression to T cell lymphoma in three. Conclusions: This retrospective longitudinal analysis of the largest monocentric cohort of CD3-CD4+ T cell associated lymphocytic variant hypereosinophilic syndrome published so far provides clinicians confronted with this rare disorder with relevant new data on patient presentation and outcome that should help tailor therapy and follow-up to different levels of disease severity. It highlights the need for novel therapeutic options, especially for the subset of patients with severe treatment-refractory disease. Future research efforts should be made toward understanding CD3-CD4+ T cell biology in order to develop new treatments that target primary pathogenic mechanisms.

Proportions of interferon-γ-producing ascites lymphocytes in response to mycobacterial antigens: A help for early diagnosis of peritoneal tuberculosis in a low TB incidence country.

BACKGROUND: Peritoneal tuberculosis (TB) remains difficult to diagnose because of its non-specific clinical features and the lack of efficient microbiological tests. As delayed diagnosis is associated with high mortality rates, new diagnostic tools are needed. METHODS AND FINDINGS: We investigated for 24 patients prospectively enrolled with a possible diagnosis of peritoneal TB, the diagnostic value of the analysis of IFN-γ production by peritoneal fluid lymphocytes in response to a short in vitro stimulation with mycobacterial antigens. The patients were classified in two groups: non-TB and confirmed or highly probable TB. Diagnosis of TB was based on microbiological and histopathological criteria and/or a favorable response to anti-TB treatment. The IFN-γ production by peritoneal CD4+ T lymphocytes was analyzed by flow cytometry after an overnight in vitro stimulation with three different mycobacterial antigens, purified protein derivative (PPD), heparin-binding haemagglutinin (HBHA) or early-secreted-antigen-target-6 (ESAT-6). The percentages of PPD-, HBHA- or ESAT-6-induced IFN-γ-producing peritoneal fluid CD4+ T lymphocytes were higher in the TB group than in the non-TB group (p = 0.0007, p = 0.0004, and p = 0.0002 respectively). Based on cut-off values determined by ROC curve analysis of the results from TB and highly probable TB compared to those of non-TB patients, the sensitivity of these three tests was 100% with a specificity of 92%. CONCLUSIONS: The analysis of mycobacterial-induced IFN-γ production by peritoneal lymphocytes is a promising tool to reliably and rapidly diagnose peritoneal TB. Further studies should be performed on larger cohorts of patients in high-TB-incidence countries to confirm the clinical value of this new diagnostic approach for peritoneal TB.

Insulin needs after CD3-antibody therapy in new-onset type 1 diabetes.

BACKGROUND: Type 1 diabetes mellitus is a T-cell-mediated autoimmune disease that leads to a major loss of insulin-secreting beta cells. The further decline of beta-cell function after clinical onset might be prevented by treatment with CD3 monoclonal antibodies, as suggested by the results of a phase 1 study. To provide proof of this therapeutic principle at the metabolic level, we initiated a phase 2 placebo-controlled trial with a humanized antibody, an aglycosylated human IgG1 antibody directed against CD3 (ChAglyCD3). METHODS: In a multicenter study, 80 patients with new-onset type 1 diabetes were randomly assigned to receive placebo or ChAglyCD3 for six consecutive days. Patients were followed for 18 months, during which their daily insulin needs and residual beta-cell function were assessed according to glucose-clamp-induced C-peptide release before and after the administration of glucagon. RESULTS: At 6, 12, and 18 months, residual beta-cell function was better maintained with ChAglyCD3 than with placebo. The insulin dose increased in the placebo group but not in the ChAglyCD3 group. This effect of ChAglyCD3 was most pronounced among patients with initial residual beta-cell function at or above the 50th percentile of the 80 patients. In this subgroup, the mean insulin dose at 18 months was 0.22 IU per kilogram of body weight per day with ChAglyCD3, as compared with 0.61 IU per kilogram with placebo (P<0.001). In this subgroup, 12 of 16 patients who received ChAglyCD3 (75 percent) received minimal doses of insulin (< or =0.25 IU per kilogram per day) as compared with none of the 21 patients who received placebo. Administration of ChAglyCD3 was associated with a moderate "flu-like" syndrome and transient symptoms of Epstein-Barr viral mononucleosis. CONCLUSIONS: Short-term treatment with CD3 antibody preserves residual beta-cell function for at least 18 months in patients with recent-onset type 1 diabetes.

Flow cytometry for basophil activation markers: the measurement of CD203c up-regulation is as reliable as CD63 expression in the diagnosis of cat allergy.

The flow cytometric basophil activation test (BAT), based on the detection of allergen-induced CD63 expression, has been proved effective in the diagnosis of various IgE-mediated allergies. However, there is not yet consensus about the suitability of CD203c expression as a specific basophil activation marker and its diagnostic reliability. The goal of the present study was to compare measurement of CD63 and CD203c expression using BAT in a model of cat allergy and to determine optimal experimental conditions for both markers. Heparinized whole blood samples from 20 cat allergic patients and 19 controls were incubated with Fel d1 (relevant allergen) or anti-FcepsilonRI (positive control) either in IL-3 or IL-3-free conditions. An optimal gating of basophils was achieved in triple staining protocols: anti-IgE PE/anti-CD45 PerCP/anti-CD63 FITC or anti-IgE FITC/anti-CD45 PerCP/anti-CD203c PE. We demonstrated that IL-3 significantly enhanced CD63-induced expression by basophils obtained from cat allergic patients in response to Fel d1. Sensitivity was found to be 100%. The CD203c protocol, when performed under IL-3-free conditions, also demonstrated 100% sensitivity. Only one of the control subjects was positive in both tests. In conclusion, using well-defined experimental conditions, the measurement of CD203c up-regulation on basophils in response to specific allergens is as reliable as CD63-BAT for the in vitro diagnosis of patients with IgE-mediated allergy.

6q- is an early and persistent chromosomal aberration in CD3-CD4+ T-cell clones associated with the lymphocytic variant of hypereosinophilic syndrome.

BACKGROUND AND OBJECTIVES: The lymphocytic variant of hypereosinophilic syndrome (LV-HES) is an underrated disease defined by the monoclonal proliferation of interleukin-5 secreting T-cells. This disease is distinguished by a period of chronic lymphoproliferation without clinical transformation, which is frequently a precursor to T-cell lymphoma. In this study, LV-HES was used as a model of pre-malignancy to identify specific marker(s) predictive of the potential for malignant transformation. DESIGN AND METHODS: The karyotypic abnormalities detected in the abnormal CD3-CD4+ T cells were further characterized by fluorescent in situ hybridization. A multi-step retrospective analysis was performed on successive blood samples during a six-year follow up to correlate the evolution of cytogenetic changes with clinical progression. Expression array analysis was used to investigate the effect of these chromosomal aberrations on gene expression. RESULTS: A 6q deletion was detected in the two LV-HES patients during their chronic disease phase. An additional 10p deletion was found alone or in association with the 6q defect in one patient prior to the development of a CD3-CD4+ T-cell lymphoma six years after diagnosis. We show that the 6q but not the 10p deletion is both stable and persistent throughout the chronic disease, finally emerging as the predominant aberration in the lymphoma cells. Six genes mapped to the 6q-deleted region displayed altered gene expression profiles both in the chronic and malignant disease phases. INTERPRETATION AND CONCLUSIONS: Our data suggest that the 6q deletion represents an early cytogenetic marker for T-cell transformation.

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.

Anaphylactic shock caused by immunoglobulin E sensitization after retreatment with the chimeric anti-interleukin-2 receptor monoclonal antibody basiliximab.

BACKGROUND: Repeated administration of chimeric or humanized monoclonal antibodies is generally well tolerated. Anti-idiotypic sensitization is rare and is considered to be of no clinical significance. We observed a child who experienced anaphylactic shock when he received a second course of basiliximab at the time of his second renal transplantation. We therefore searched for the presence of anti-basiliximab immunoglobulin (Ig) E in this patient. METHODS: Serum levels of anti-basiliximab IgE, assay of the anti-murine reactivity of circulating anti-basiliximab IgE, and assays for serum anti-mouse antibodies and global anti-basiliximab anti-idiotypic antibodies were carried out by enzyme-linked immunosorbent assay. Anti-basiliximab IgE antibodies on circulating basophils were evaluated by the ability of the patient's blood to produce leukotrienes in vitro after exposure to basiliximab. RESULTS: Sequential assays of serum samples by enzyme-linked immunosorbent assay indicated that anti-basiliximab IgE antibodies appeared after the second basiliximab course. There was no IgE reactivity toward a control murine IgG2a monoclonal antibody (mAb), indicating that the IgE response was directed exclusively against basiliximab idiotypes. There was no IgE reactivity against the humanized anti-interleukin-2 receptor mAb daclizumab, which was derived from a distinct parental murine mAb. Patient basophils harvested months after the anaphylactic shock produced leukotrienes in vitro on exposure to basiliximab. CONCLUSIONS: Patients exposed to chimeric antibodies may develop an anti-idiotypic IgE response that can trigger anaphylactic shock on further exposure. Specific anti-idiotypic IgE may be bound to basophils even in the absence of circulating IgE.

Increased production of interleukin-10 and interleukin-1 receptor antagonist after extracorporeal photochemotherapy in chronic graft-versus-host disease.

BACKGROUND: Mechanisms of action of extracorporeal photochemotherapy (ECP) in graft-versus-host disease are incompletely understood. It has been proposed that phagocytosis of apoptotic bodies by monocytes and macrophages induces their activation, a process that increases production of immunosuppressive cytokines. We analyzed apoptosis and cytokine secretion in an autologous coculture system combining peripheral blood lymphocytes (PBL) obtained after ex vivo ECP treatment and nonirradiated peripheral blood mononuclear cells (PBMC). METHODS: We studied 11 leukapheresis products treated by ECP from six patients with resistant limited or extensive chronic graft-versus-host disease. Purified PBL obtained by monocyte depletion of the buffy coat from leukapheresis products were mixed with nonirradiated PBMC. Nonirradiated PBL were used as control. Cytokine production was tested at the mRNA level by real-time reverse transcriptase-polymerase chain reaction for interleukin (IL)-10, IL-1 receptor antagonist (IL-1Ra), IL-1beta, tumor necrosis factor-alpha, and IL-12p40. RESULTS: Morphologic analysis and flow cytometry displayed important lymphocyte apoptotic features culminating at 24 to 48 hr. Coculture of patient's PBMC with ultraviolet-irradiated PBL as compared with nonirradiated PBL resulted in significant increase of IL-10 mRNA (3418+/-1015 versus 10596+/-3402 mRNA copy numbers; P=0.001) and IL-1Ra mRNA (23890+/-6166 versus 41767+/-10181 mRNA copy numbers; P=0.001). Incubation with a neutralizing anti-IL-10 monoclonal antibody resulted in a marked decrease of IL-1Ra mRNA levels. CONCLUSION: Our findings are consistent with the fact that ECP modifies patient's autologous lymphocytes by inducing a process of apoptosis that activates monocytes and macrophages, leading to increased synthesis of IL-10 and IL-1Ra mRNAs. The induction of this latter mediator is dependent on IL-10.

Age-related immune reconstitution during highly active antiretroviral therapy in human immunodeficiency virus type 1-infected children.

OBJECTIVES: To evaluate the immune reconstitution in HIV-1-infected children in whom highly active antiretroviral therapy (HAART) controlled viral replication and to assess the existence of a relation between the magnitude of this restoration and age. METHODS: All HIV-1-infected children in whom a new HAART decreased plasma viral load below 400 copies/ml after 3 months of therapy were prospectively enrolled in a study of their immune reconstitution. Viral load, lymphocyte phenotyping, determination of CD4+ and CD8+ T cell receptor repertoires and proliferative responses to mitogens and recall antigens were assessed every 3 months during 1 year. RESULTS: Nineteen children were evaluated. Naive and memory CD4+ percentages were already significantly increased after 3 months of HAART. In contrast to memory CD4+ percentages, naive CD4+ percentages continued to rise until 12 months. Age at baseline was inversely correlated with the magnitude of the rise in naive CD4+ cells after 3, 6 and 9 months of therapy but not after 12 months. Although memory and activated CD8+ cells were already decreasing after 3 months, abnormalities of the CD8 T cell receptor repertoire and activation of CD8+ cells persisted at 1 year. HAART increased the response to mitogens as early as 3 months after starting therapy. CONCLUSIONS: In children the recovery of naive CD4+ cells occurs more rapidly if treatment is started at a younger age, but after 1 year of viral replication control, patients of all ages have achieved the same level of restoration. Markers of chronic activation in CD8+ cells persist after 1 year of HAART.

Donor stem cell infusion after non-myeloablative conditioning for tolerance induction to HLA mismatched adult living-donor liver graft.

BACKGROUND AND AIM OF THE STUDY: The induction of transplantation tolerance, defined as the survival of a functioning allograft in the absence of continuing immunosuppressive therapy, would be a major advance. Clinical and experimental data have shown that transplantation tolerance could be induced by pre-transplant myeloconditioning and infusion of donor hematopoietic cells. We investigated the feasibility and safety of a protocol to induce tolerance to HLA mismatched living-donor liver graft by pre-transplant non-myeloablative conditioning followed by donor stem cells (SC) infusion, in patients with advanced liver cancers. PATIENTS AND METHODS: Two patients with intrahepatic cancers who did not fulfill criteria for cadaver liver transplantation were included in the study. Preparative regimen consisted in cyclophosphamide and anti-thymocyte globulin, followed by infusion of purified donor CD34(+) stem cells. Living-donor liver transplantation (LDLT) using the liver right lobe was performed after hematological reconstitution, respectively 40 and 55 days after donor stem cell infusion. Immunosuppressive therapies were discontinued when liver graft function returned to normal. RESULTS: The procedure could be completed in the two patients. No severe toxicity of the preparative regimen was observed. Neither patient presented graft versus host reaction after donor stem cell infusion. A transient macrochimerism was observed in the first case, while no chimerism could be detected in the second. Immunosuppression was discontinued, respectively 90 and 28 days, after liver transplantation, without subsequent rejection episode. In the two cases, liver function remained normal for the study period. In both patients, the period of immune reconstitution was prolonged, as illustrated by persisting low CD4(+) cell counts. Mixed lymphocyte cultures, performed after immunosuppression withdrawal, demonstrated donor specific hyporesponsiveness in the first case, but in a context of global hyporeactivity in the two patients. The first patient died from tumor recurrence 370 days after liver transplantation. The second patient is alive, 270 days after liver transplantation, but with a suspicion of tumor relapse as indicated by the reappearance of tumor marker in blood. CONCLUSION: In the two cases, acceptance of HLA mismatched living-donor liver graft was obtained after non-myeloablative conditioning and donor stem cell infusion. Improving the rate of immune reconstitution appears as a priority to reduce the risk of tumor recurrence in such patients.

Trapidil inhibits monocyte CD40 expression by preventing IFN-gamma-induced STAT1 S727 phosphorylation.

Trapidil is a triazolopyrimidine that has been found to prevent restenosis after vascular injury. Although its precise mode of action is still unclear, several biological effects have been described including inhibition of IFN-gamma-induced CD40 expression on monocytes. Herein, we investigated the molecular mechanisms by which Trapidil exerts this inhibitory action. First, we observed that the inhibition of CD40 expression is associated with the suppression of CD40 gene transcription, as demonstrated by a clear decrease of CD40 nuclear RNA (nRNA) levels and unchanged CD40 mRNA half-life. IFN-gamma-induced CD40 transcription has been shown to be mediated by STAT1alpha dimers (p91/p84) which, after nuclear translocation, bind to GAS elements present in the promoter of IFN-gamma responsive genes. Electrophoresis mobility shift assay (EMSA) with both STAT1 consensus and CD40 mGAS probes showed that Trapidil did not affect the DNA binding ability of STAT1 dimers. STAT1 dimerization and activation are conferred by upstream phosphorylation of two amino acid residues of the STAT1 protein. The subsequent studies on these two potential STAT1 phosphorylation sites (Tyr701, Ser727) revealed that Trapidil attenuated IFN-gamma-induced Ser727 but not Tyr701 phosphorylation. The inhibition of CD40 transcription by Trapidil could at least partially owing to the impaired Ser727 phosphorylation of STAT1, since IFN-gamma failed to trigger CD40 expression in U3A S727A cells, a cell line displaying a point mutation at the Ser727 site. Collectively, our results indicate that phosphorylation of STAT1 at the Ser727 site enhances CD40 transcription and that Trapidil might be used as a selective inhibitor that could differentially modulate STAT1 target genes.