First-in-Human Study in Healthy Subjects with the Noncytotoxic Monoclonal Antibody OSE-127, a Strict Antagonist of IL-7Rα.

OSE-127 is a humanized mAb targeting the IL-7Rα-chain (CD127), under development for inflammatory and autoimmune disease treatment. It is a strict antagonist of the IL-7R pathway, is not internalized by target cells, and is noncytotoxic. In this work, a first-in-human, phase I, randomized, double-blind, placebo-controlled, single-center study was carried out to determine the safety, pharmacokinetics, pharmacodynamics, and immunogenicity of OSE-127 administration. Sixty-three healthy subjects were randomly assigned to nine groups: six single ascending dose groups with i.v. administration (0.002-10 mg/kg), a single s.c. treatment group (1 mg/kg), and two double i.v. injection groups (6 or 10 mg/kg). Subjects were followed during <146 d. OSE-127's pharmacokinetic half-life after a single dose increased from 4.6 (1 mg/kg) to 11.7 d (10 mg/kg) and, after a second dose, from 12.5 (6 mg/kg) to 16.25 d (10 mg/kg). Receptor occupancy was ≥95% at doses ≥0.02 mg/kg, and this saturation level was maintained >100 d after two i.v. infusions at 10 mg/kg. IL-7 consumption was inhibited by OSE-127 administration, as demonstrated by a decreased IL-7 pathway gene signature in peripheral blood cells and by ex vivo T lymphocyte restimulation experiments. OSE-127 was well tolerated, with no evidence of cytokine-release syndrome and no significant alteration of blood lymphocyte counts or subset populations. Altogether, the observed lack of significant lymphopenia or serious adverse events, concomitant with the dose-dependent inhibition of IL-7 consumption by target cells, highlights that OSE-127 may show clinical activity in IL-7R pathway-involved diseases.

A Phase I/IIa study of autologous tolerogenic dendritic cells immunotherapy in kidney transplant recipients.

Kidney transplant survival is shortened by chronic rejection and side effects of standard immunosuppressive drugs. Cell-based immunotherapy with tolerogenic dendritic cells has long been recognized as a promising approach to reduce general immunosuppression. Published trials report the safety and the absence of therapy-related adverse reactions in patients treated with tolerogenic dendritic cells suffering from several inflammatory diseases. Here, we present the first phase I clinical trial results using human autologous tolerogenic dendritic cells (ATDC) in kidney transplantation. Eight patients received ATDC the day before transplantation in conjunction with standard steroids, mycophenolate mofetil and tacrolimus immunosuppression with an option to taper mycophenolate mofetil. ATDC preparations were manufactured in a Good Manufacturing Practice-compliant facility and fulfilled cell count, viability, purity and identity criteria for release. A control group of nine patients received the same standard immunosuppression, except basiliximab induction replaced ATDC therapy and mycophenolate tapering was not allowed. During the three-year follow-up, no deaths occurred and there was 100% graft survival. No significant increase of adverse events was associated with ATDC infusion. Episodes of rejection were observed in two patients from the ATDC group and one patient from the control group. However, all rejections were successfully treated by glucocorticoids. Mycophenolate was successfully reduced/stopped in five patients from the ATDC group, allowing tacrolimus monotherapy for two of them. Regarding immune monitoring, reduced CD8 T cell activation markers and increased Foxp3 expression were observed in the ATDC group. Thus, our results demonstrate ATDC administration safety in kidney-transplant recipients.

Non-permissive human conventional CD1c+ dendritic cells enable trans-infection of human primary renal tubular epithelial cells and protect BK polyomavirus from neutralization.

The BK polyomavirus (BKPyV) is a ubiquitous human virus that persists in the renourinary epithelium. Immunosuppression can lead to BKPyV reactivation in the first year post-transplantation in kidney transplant recipients (KTRs) and hematopoietic stem cell transplant recipients. In KTRs, persistent DNAemia has been correlated to the occurrence of polyomavirus-associated nephropathy (PVAN) that can lead to graft loss if not properly controlled. Based on recent observations that conventional dendritic cells (cDCs) specifically infiltrate PVAN lesions, we hypothesized that those cells could play a role in BKPyV infection. We first demonstrated that monocyte-derived dendritic cells (MDDCs), an in vitro model for mDCs, captured BKPyV particles through an unconventional GRAF-1 endocytic pathway. Neither BKPyV particles nor BKPyV-infected cells were shown to activate MDDCs. Endocytosed virions were efficiently transmitted to permissive cells and protected from the antibody-mediated neutralization. Finally, we demonstrated that freshly isolated CD1c+ mDCs from the blood and kidney parenchyma behaved similarly to MDDCs thus extending our results to cells of clinical relevance. This study sheds light on a potential unprecedented CD1c+ mDC involvement in the BKPyV infection as a promoter of viral spreading.

Monocyte Signature Associated with Herpes Simplex Virus Reactivation and Neurological Recovery after Brain Injury.

Rationale: Brain injury induces systemic immunosuppression, increasing the risk of viral reactivations and altering neurological recovery. Objectives: To determine if systemic immune alterations and lung replication of herpesviridae are associated and can help predict outcomes after brain injury. Methods: We collected peripheral blood mononuclear cells in patients with severe brain injury requiring invasive mechanical ventilation. We systematically searched for respiratory herpes simplex virus (HSV) replications in tracheal aspirates. We also performed chromatin immunoprecipitation sequencing, RNA-sequencing, and in vitro functional assays of monocytes and CD4 T cells collected on Day 1 to characterize the immune response to severe acute brain injury. The primary outcome was the Glasgow Outcome Scale Extended at 6 months. Measurements and Main Results: In 344 patients with severe brain injury, lung HSV reactivations were observed in 39% of the 232 patients seropositive for HSV and independently associated with poor neurological recovery at 6 months (hazard ratio, 1.90; 95% confidence interval, 1.08-3.57). Weighted gene coexpression network analyses of the transcriptomic response of monocytes to brain injury defined a module of 721 genes, including PD-L1 and CD80, enriched for the binding DNA motif of the transcriptional factor Zeb2 and whose ontogenic analyses revealed decreased IFN-γ-mediated and antiviral response signaling pathways. This monocyte signature was preserved in a validation cohort and predicted the neurological outcome at 6 months with good accuracy (area under the curve, 0.786; 95% confidence interval, 0.593-0.978). Conclusions: A specific monocyte signature is associated with HSV reactivation and predicts poor recovery after brain injury. The alterations of the immune control of herpesviridae replication are understudied and represent a novel therapeutic target.

Preformed T cell alloimmunity and HLA eplet mismatch to guide immunosuppression minimization with tacrolimus monotherapy in kidney transplantation: Results of the CELLIMIN trial.

Personalizing immunosuppression is a major objective in transplantation. Transplant recipients are heterogeneous regarding their immunological memory and primary alloimmune susceptibility. This biomarker-guided trial investigated whether in low immunological-risk kidney transplants without pretransplant DSA and donor-specific T cells assessed by a standardized IFN-γ ELISPOT, low immunosuppression (LI) with tacrolimus monotherapy would be non-inferior regarding 6-month BPAR than tacrolimus-based standard of care (SOC). Due to low recruitment rates, the trial was terminated when 167 patients were enrolled. ELISPOT negatives (E-) were randomized to LI (n = 48) or SOC (n = 53), E+ received the same SOC. Six- and 12-month BPAR rates were higher among LI than SOC/E- (4/35 [13%] vs. 1/43 [2%], p = .15 and 12/48 [25%] vs. 6/53 [11.3%], p = .073, respectively). E+ patients showed similarly high BPAR rates than LI at 6 and 12 months (12/55 [22%] and 13/66 [20%], respectively). These differences were stronger in per-protocol analyses. Post-hoc analysis revealed that poor class-II eplet matching, especially DQ, discriminated E- patients, notably E-/LI, developing BPAR (4/28 [14%] low risk vs. 8/20 [40%] high risk, p = .043). Eplet mismatch also predicted anti-class-I (p = .05) and anti-DQ (p < .001) de novo DSA. Adverse events were similar, but E-/LI developed fewer viral infections, particularly polyoma-virus-associated nephropathy (p = .021). Preformed T cell alloreactivity and HLA eplet mismatch assessment may refine current baseline immune-risk stratification and guide immunosuppression decision-making in kidney transplantation.

Regulatory cell therapy in kidney transplantation (The ONE Study): a harmonised design and analysis of seven non-randomised, single-arm, phase 1/2A trials.

BACKGROUND: Use of cell-based medicinal products (CBMPs) represents a state-of-the-art approach for reducing general immunosuppression in organ transplantation. We tested multiple regulatory CBMPs in kidney transplant trials to establish the safety of regulatory CBMPs when combined with reduced immunosuppressive treatment. METHODS: The ONE Study consisted of seven investigator-led, single-arm trials done internationally at eight hospitals in France, Germany, Italy, the UK, and the USA (60 week follow-up). Included patients were living-donor kidney transplant recipients aged 18 years and older. The reference group trial (RGT) was a standard-of-care group given basiliximab, tapered steroids, mycophenolate mofetil, and tacrolimus. Six non-randomised phase 1/2A cell therapy group (CTG) trials were pooled and analysed, in which patients received one of six CBMPs containing regulatory T cells, dendritic cells, or macrophages; patient selection and immunosuppression mirrored the RGT, except basiliximab induction was substituted with CBMPs and mycophenolate mofetil tapering was allowed. None of the trials were randomised and none of the individuals involved were masked. The primary endpoint was biopsy-confirmed acute rejection (BCAR) within 60 weeks after transplantation; adverse event coding was centralised. The RTG and CTG trials are registered with ClinicalTrials.gov, NCT01656135, NCT02252055, NCT02085629, NCT02244801, NCT02371434, NCT02129881, and NCT02091232. FINDINGS: The seven trials took place between Dec 11, 2012, and Nov 14, 2018. Of 782 patients assessed for eligibility, 130 (17%) patients were enrolled and 104 were treated and included in the analysis. The 66 patients who were treated in the RGT were 73% male and had a median age of 47 years. The 38 patients who were treated across six CTG trials were 71% male and had a median age of 45 years. Standard-of-care immunosuppression in the recipients in the RGT resulted in a 12% BCAR rate (expected range 3·2-18·0). The overall BCAR rate for the six parallel CTG trials was 16%. 15 (40%) patients given CBMPs were successfully weaned from mycophenolate mofetil and maintained on tacrolimus monotherapy. Combined adverse event data and BCAR episodes from all six CTG trials revealed no safety concerns when compared with the RGT. Fewer episodes of infections were registered in CTG trials versus the RGT. INTERPRETATION: Regulatory cell therapy is achievable and safe in living-donor kidney transplant recipients, and is associated with fewer infectious complications, but similar rejection rates in the first year. Therefore, immune cell therapy is a potentially useful therapeutic approach in recipients of kidney transplant to minimise the burden of general immunosuppression. FUNDING: The 7th EU Framework Programme.

First-in-Human Study in Healthy Subjects with FR104, a Pegylated Monoclonal Antibody Fragment Antagonist of CD28.

FR104 is a monovalent pegylated Fab' Ab, antagonist of CD28, under development for treatment of transplant rejection and autoimmune diseases. In contrast to CD80/86 antagonists (CTLA4-Ig), FR104 selectively blunts CD28 costimulation while sparing CTLA-4 and PD-L1 coinhibitory signals. In the present work, FR104 has been evaluated in a first-in-human study to evaluate the safety, pharmacokinetics, pharmacodynamics, and potency of i.v. administrations in healthy subjects. Sixty-four subjects were randomly assigned to four single ascending dose groups, two double dose groups and four single ascending dose groups challenged with keyhole limpet hemocyanin. Subjects were followed up over a maximum of 113 d. Overall, the pharmacokinetics of FR104 after a single and double infusions was approximately linear at doses ≥0.200 mg/kg. CD28 receptor occupancy by FR104 was saturated at the first sampling time point (0.5 h) at doses above 0.02 mg/kg and returned to 50% in a dose-dependent manner, by day 15 (0.020 mg/kg) to 85 (1.500 mg/kg). FR104 was well tolerated, with no evidence of cytokine-release syndrome and no impact on blood lymphocyte subsets. Inhibition of anti-keyhole limpet hemocyanin Ab response was dose-dependent in FR104 recipients and was already apparent at a dose of 0.02 mg/kg. Abs to FR104 were detected in 22/46 (48%) of FR104 recipients and only 1/46 (2.2%) was detected during drug exposure. In conclusion, selective blockade of CD28 with FR104 was safe and well tolerated at the doses tested. The observed immunosuppressive activity indicated that FR104 has potential to show clinical activity in the treatment of immune-mediated diseases.

Standardized whole blood stimulation improves immunomonitoring of induced immune responses in multi-center study.

Functional immune responses are increasingly important for clinical studies, providing in depth biomarker information to assess immunotherapy or vaccination. Incorporating functional immune assays into routine clinical practice has remained limited due to challenges in standardizing sample preparation. We recently described the use of a whole blood syringe-based system, TruCulture®, which permits point-of-care standardized immune stimulation. Here, we report on a multi-center clinical study in seven FOCIS Centers of Excellence to directly compare TruCulture to conventional PBMC methods. Whole blood and PBMCs from healthy donors were exposed to LPS, anti-CD3 anti-CD28 antibodies, or media alone. 55 protein analytes were analyzed centrally by Luminex multi-analyte profiling in a CLIA-certified laboratory. TruCulture responses showed greater reproducibility and improved the statistical power for monitoring differential immune response activation. The use of TruCulture addresses a major unmet need through a robust and flexible method for immunomonitoring that can be reproducibly applied in multi-center clinical studies. ONE SENTENCE SUMMARY: A multi-center study revealed greater reproducibility from whole blood stimulation systems as compared to PBMC stimulation for studying induced immune responses.

Persistent deficiency of circulating mucosal-associated invariant T (MAIT) cells in ANCA-associated vasculitis.

OBJECTIVE: Mucosal associated invariant T cells (MAIT) and innate lymphoid cells (ILCs) have immunoregulatory functions at mucosal sites and have been involved in various inflammatory and autoimmune diseases. The aim of this study was to assess their frequencies in blood in ANCA-associated vasculitis (AAV). METHODS: The frequencies and function of MAIT cells, ILCs, γδT, iNKT, NK cells were analyzed by flow cytometry on PBMC of patients with granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA) without any treatment, in acute (AP) and remission phase (RP) and compared with healthy controls (HC). RESULTS: The frequencies of MAIT cells were strongly decreased in GPA and MPA in AP compared to HC, both in never treated and in relapsing patients and independently of patient age. This was associated with an activated phenotype of patient MAIT cells, as shown by increased expression of CD69 and IFNγ. MAIT cells remained decreased during RP in AAV patients. The frequencies of iNKT and γδT cells were unaffected compared to HC, whereas those of NK cells were slightly reduced during AP in MPA. We also observed a significant decrease in frequencies of total ILCs with decreased ILC2 and ILC3 and increased ILC1 during AP in both GPA and MPA compared to HC. These frequencies normalized during RP. Interestingly, we observed a significant correlation between the frequency of total ILCs and BVAS. CONCLUSION: We show for the first time that AAV are associated with a major decrease and an activated phenotype of blood MAIT cell. These features persisted during remission suggesting a role for MAIT cells in the pathogenesis of AAV.

Hydrocortisone prevents immunosuppression by interleukin-10+ natural killer cells after trauma-hemorrhage.

OBJECTIVE: Trauma induces a state of immunosuppression, which is responsible for the development of nosocomial infections. Hydrocortisone reduces the rate of pneumonia in patients with trauma. Because alterations of dendritic cells and natural killer cells play a central role in trauma-induced immunosuppression, we investigated whether hydrocortisone modulates the dendritic cell/natural killer cell cross talk in the context of posttraumatic pneumonia. DESIGN: Experimental study. SETTINGS: Research laboratory from an university hospital. SUBJECTS: Bagg Albino/cJ mice (weight, 20-24 g). INTERVENTIONS: First, in an a priori substudy of a multicenter, randomized, double-blind, placebo-controlled trial of hydrocortisone (200 mg/d for 7 d) in patients with severe trauma, we have measured the blood levels of five cytokines (tumor necrosis factor-α, interleukin-6, interleukin-10, interleukin-12, interleukin-17) at day 1 and day 8. In a second step, the effects of hydrocortisone on dendritic cell/natural killer cell cross talk were studied in a mouse model of posttraumatic pneumonia. Hydrocortisone (0.6 mg/mice i.p.) was administered immediately after hemorrhage. Twenty-four hours later, the mice were challenged with Staphylococcus aureus (7 × 10 colony-forming units). MEASUREMENTS AND MAIN RESULTS: Using sera collected during a multicenter study in patients with trauma, we found that hydrocortisone decreased the blood level of interleukin-10, a cytokine centrally involved in the regulation of dendritic cell/natural killer cell cluster. In a mouse model of trauma-hemorrhage-induced immunosuppression, splenic natural killer cells induced an interleukin-10-dependent elimination of splenic dendritic cell. Hydrocortisone treatment reduced this suppressive function of natural killer cells and increased survival of mice with posthemorrhage pneumonia. The reduction of the interleukin-10 level in natural killer cells by hydrocortisone was partially dependent on the up-regulation of glucocorticoid-induced tumor necrosis factor receptor-ligand (TNFsf18) on dendritic cell. CONCLUSIONS: These data demonstrate that trauma-induced immunosuppression is characterized by an interleukin-10-dependent elimination of dendritic cell by natural killer cells and that hydrocortisone improves outcome by limiting this immunosuppressive feedback loop.

Confocal laser endomicroscopy as predictive biomarker of clinical and endoscopic efficacy of vedolizumab in ulcerative colitis: The DETECT study.

AIMS: In patients with ulcerative colitis (UC), no biomarker is available to help the physician to choose the most suitable biotherapy. The primary objective of this pilot study was to assess the feasibility of identification of α4ß7- and TNF-expressing cells, to predict the response to vedolizumab using confocal laser endoscopy (CLE). METHODS: Patients with moderate-to-severe UC, naïve of biotherapy, received vedolizumab. Clinical evaluation was performed at each infusion. Endoscopic evaluation was performed before inclusion and at week 22. Fresh colonic biopsies were stained using FITC-labelled vedolizumab and Alexa fluor-labelled adalimumab and ex vivo dual-band CLE images were acquired. Blood samples were collected to measure trough concentrations of vedolizumab and to determine absolute counts of T and B cells subpopulations, NK cells and monocytes. RESULTS: Nineteen patients were enrolled in the study and received at least one dose of vedolizumab. Clinical remission and endoscopic improvement were observed in 58% of whom 5 patients (45%) had an endoscopic subscore of 0. In terms of clinical response and remission, endoscopic improvement and histologic response, FITC-conjugated vedolizumab staining tended to be higher in responder patients compared to non-responders at week 22. A threshold value of 6 positive FITC-vedolizumab staining areas detected by CLE seemed informative to discriminate the responders and non-responders. The results were similar in terms of clinical remission and endoscopic improvement with a sensitivity of 78% and a specificity of 85% (p = 0.05). Trough concentrations and blood immune cells were not associated with responses to vedolizumab. CONCLUSION: This pilot study demonstrate that dual-band CLE is feasible to detect α4ß7- and TNF-expressing cells. Positive α4ß7 staining seems to be associated with clinical and endoscopic remission in UC patients treated by anti-α4ß7-integrin, subject to validation by larger-scale studies. Clinical-trial.gov: NCT02878083.

Altered innate function of plasmacytoid dendritic cells restored by enzyme replacement therapy in Gaucher disease.

BACKGROUND: Gaucher disease (GD) is caused by an autosomal-recessive deficiency of ß-glucocerebrosidase leading to an accumulation of glucosylceramide in monocytes/macrophage lineage. We analyzed immune cells and especially the function of dendritic cells to evaluate the potential impact of glucosylceramide accumulation in these cells and its possible role in infections and malignancies usually described in this pathology. These analyses were performed for each patient without and under enzyme replacement therapy. METHODS: Seven GD patients were studied and compared with healthy volunteers. Immune cells (B cells, T cells, NK, dendritic cells), were analyzed by flow cytometry directly on whole blood. Cytokine production by blood dendritic cells was assessed after stimulation by toll-like receptor ligands. Cytokines in sera were measured using a multiplex assay. RESULTS: GD patients displayed decreased numbers of NK cells, γδ2 T cells and increased frequency of memory CD4(+)CD45RO(+) T cells, when compared to healthy controls. Numbers of dendritic cells (myeloid (mDC) and plasmacytoid (pDC) dendritic cells) were also decreased. We demonstrated that pDC from GD patients exhibited a decrease in IFNα production after TLR9 stimulation compared to controls. Importantly, enzyme replacement therapy restored pDC function. Finally, we observed an increase of IL-8 and IL-18 in GD patient sera, which were reduced under enzyme replacement therapy. CONCLUSIONS: Our data confirm that patients with GD exhibit altered numbers of innate and T lymphocytes and show for the first time that pDC from GD patients exhibit altered responsiveness to TLR9. These alterations could contribute to a decreased response to pathogens and could favor the development of malignancies.

The risk of COVID-19 in IBD patients is increased by urban living and is not influenced by disease activity or intravenous biologics.

Background: Patients with inflammatory bowel disease (IBD) may have a modified immune response to SARS-CoV-2. The objectives were to evaluate the prevalence of COVID-19 in patients treated with infliximab or vedolizumab, to analyze the factors associated with the infection, the impact of treatments and trough levels. Methods: Patients with IBD treated with intravenous biologics in 14 French centers were included between March and June 2020 and followed-up for 6 months. Blood samples were collected for serologies and trough levels. The analysis of factors associated with COVID-19 was conducted in a matched 1:1 case-control sub-study with positive patients. Results: In total, 1026 patients were included (74.9% infliximab). Over the follow-up period, 420 patients reported the occurrence of COVID-19 symptoms; 342 had been tested of whom 18 were positive. At the end of follow-up, 38 patients had a positive serology. Considering both nasal tests and serologies together, 46 patients (4.5%) had been infected. The risk of COVID-19 was related neither to the use of treatments (whatever the trough levels) nor to disease activity. Infections were more frequent when using public transport or living in flats in urban areas. Conclusions: The prevalence rate of COVID-19 in this IBD population treated with intravenous infliximab or vedolizumab was the same as the one in the French population before the start of the vaccination campaign. The risk was increased by urban living and was not influenced by disease activity or biologics. Sanitary barrier measures remain the best way to protect against SARS-CoV-2 in patients with IBD in biological therapy.

IL-22BP production is heterogeneously distributed in Crohn's disease.

Crohn's disease (CD), a form of inflammatory bowel disease (IBD), is characterized by impaired epithelial barrier functions and dysregulated mucosal immune responses. IL-22 binding protein (IL-22BP) is a soluble inhibitor regulating IL-22 bioactivity, a cytokine proposed to play protective roles during CD. We and others have shown that IL-22BP is produced in IBD inflamed tissues, hence suggesting a role in CD. In this work, we extended the characterization of IL-22BP production and distribution in CD tissues by applying enzyme-linked immunosorbent assays to supernatants obtained from the culture of endoscopic biopsies of patients, and reverse transcription-quantitative polymerase chain reaction on sorted immune cell subsets. We reveal that IL-22BP levels are higher in inflamed ileums than colons. We observe that in a cell-intrinsic fashion, populations of mononuclear phagocytes and eosinophils express IL-22BP at the highest levels in comparison to other sources of T cells. We suggest the enrichment of intestinal eosinophils could explain higher IL-22BP levels in the ileum. In inflamed colon, we reveal the presence of increased IL-22/IL22BP ratios compared to controls, and a strong correlation between IL-22BP and CCL24. We identify monocyte-derived dendritic cells (moDC) as a cellular subtype co-expressing both cytokines and validate our finding using in vitro culture systems. We also show that retinoic acid induces the secretion of both IL-22BP and CCL24 by moDC. Finally, we report on higher IL-22BP levels in active smokers. In conclusion, our work provides new information relevant to therapeutic strategies modulating IL-22 bioactivity in CD, especially in the context of disease location.

Transfusion-Related Renal Dysfunction After Cardiac Surgery: The Role of Myeloid-Related Protein_14 in Neutrophil-Mediated Tubular Damage.

Transfusion is a specific cause of acute kidney injury (AKI) after cardiac surgery. Whether there is an association between the composition of blood products and the onset of AKI is unknown. The present study suggests that the transfusion of packed red blood cells containing a high amount of myeloid-related protein 14 (MRP_14) could increase the incidence of AKI after cardiac surgery. In a mouse model, MRP_14 increased the influx of neutrophils in the kidney after ischemia-reperfusion and their ability to damage tubular cells. Higher concentrations of MRP_14 were found in packed red blood cells from female donors or prepared by whole blood filtration.

Patients with relapsing-remitting multiple sclerosis have normal Treg function when cells expressing IL-7 receptor alpha-chain are excluded from the analysis.

Multiple sclerosis (MS) is a chronic inflammatory disease that results in demyelination in the central nervous system, and a defect in the regulatory function of CD4+CD25high T cells has been implicated in the pathogenesis of the disease. Here, we reanalyzed the function of this T cell subset in patients with MS, but we depleted cells expressing IL-7 receptor alpha-chain (CD127), a marker recently described as present on activated T cells but not Tregs. Similar to other studies, we observed a marked defect in the suppressive function of unseparated CD4+CD25high T cells isolated from MS patients. However, when CD127(high) cells were removed from the CD4+CD25high population, patient and control cells inhibited T cell proliferation and cytokine production equally. Likewise, when the CD25 gate used to sort the cells was stringent enough to eliminate CD127high cells, CD4+CD25high T cells from patients with MS and healthy individuals had similar regulatory function. Additional analysis indicated that the CD127high cells within the CD4+CD25high T cell population from patients with MS appeared more proliferative and secreted more IFN-gamma and IL-2 than the same cells from healthy individuals. Taken together, we conclude that CD4+CD25highCD127low Tregs from MS patients and healthy individuals exhibit similar suppressive functions. The decreased inhibitory function of unfractioned CD4+CD25high cells previously observed might be due to abnormal activation of CD127high T cells in patients with MS.

Analysis of the peripheral T-cell repertoire in kidney transplant patients.

The long-term stability of renal grafts depends on the absence of chronic rejection. As T cells play a key role in rejection processes, analyzing the T-cell repertoire may be useful for understanding graft function outcomes. We have therefore investigated the power of a new statistical tool, used to analyze the peripheral blood TCR repertoire, for determining immunological differences in a group of 229 stable renal transplant patients undergoing immunosuppression. Despite selecting the patients according to stringent criteria, the patients displayed heterogeneous T-cell repertoire usage, ranging from unbiased to highly selected TCR repertoires; a skewed TCR repertoire correlating with an increase in the CD8(+) /CD4(+) T-cell ratio. T-cell repertoire patterns were compared in patients with clinically opposing outcomes i.e. stable drug-free operationally tolerant recipients and patients with the "suspicious" form of humoral chronic rejection and were found significantly different, from polyclonal to highly selected TCR repertoires, respectively. Moreover, a selected TCR repertoire was found to positively correlate with the Banff score grade. Collectively, these data suggest that TCR repertoire categorization might be included in the calculation of a composite score for the follow-up of patients after kidney transplantation.

An easy and reliable whole blood freezing method for flow cytometry immuno-phenotyping and functional analyses.

BACKGROUND: Immune profiling by flow cytometry is not always possible on fresh blood samples due to time and/or transport constraints. Furthermore, the cryopreservation of peripheral blood mononuclear cells (PBMC) requires on-site specialized lab facilities, thus severely restricting the extent to which blood immune monitoring can be applied to multicenter clinical studies. These major limitations can be addressed through the development of simplified whole blood freezing methods. METHODS: In this report, we describe an optimized easy protocol for rapid whole blood freezing with the CryoStor® CS10 solution. Using flow cytometry, we compared cellular viability and composition on cryopreserved whole blood samples to matched fresh blood, as well as fresh and frozen PBMC. RESULTS: Though partial loss of neutrophils was observed, leucocyte viability was routinely >75% and we verified the preservation of viable T cells, NK cells, monocytes, dendritic cells, and eosinophils in frequencies similar to those observed in fresh samples. A moderate decrease in B cell frequencies was observed. Importantly, we validated the possibility to analyze major intracellular markers, such as FOXP3 and Helios in regulatory T cells. Finally, we demonstrated good functional preservation of CS10-cryopreserved cells through the analysis of intracellular cytokine production in ex vivo stimulated T cells (IFNg, IL-4, IL-17A,) and monocytes (IL-1b, IL-6, TNFa). CONCLUSIONS: In conclusion, our protocol provides a robust method to apply reliable immune monitoring studies to cryopreserved whole blood samples, hence offering new important opportunities for the design of future multicenter clinical trials.

Monocytic Human Leukocyte Antigen DR Expression in Young Infants Undergoing Cardiopulmonary Bypass.

BACKGROUND: Monocytic human leukocyte antigen DR (mHLA-DR) expression levels have been reported to be a marker of immunosuppression and a predictor of sepsis and mortality. There are, however, scant data regarding mHLA-DR monitoring in young infants after cardiopulmonary bypass. Our objectives were to investigate the kinetics of mHLA-DR expression and to determine whether mHLA-DR levels are associated with healthcare-associated infection (HAI) after cardiopulmonary bypass in young infants. METHODS: mHLA-DR levels were analyzed by flow cytometry using a standardized method in 49 infants (<3 months old) with congenital heart disease before and after cardiopulmonary bypass. Results are expressed as the number of anti-HLA-DR antibodies per cell (AB/c). RESULTS: Postoperative mHLA-DR expression was reduced in all infants. Eleven patients (22%) developed HAI, and 4 patients (8%) died during the 30-day follow-up. mHLA-DR expression was significantly lower on postoperative day 4 in the HAI group compared with those who without HAI (3768 AB/c [range, 1938-6144] vs 13,230 AB/c [range, 6152-19,130], P = .014). Although mHLA-DR expression was associated with postoperative severity, mHLA-DR ≤4500 AB/c in the first 72 hours among patients with higher postoperative severity (extracorporeal membrane oxygenation and/or corticoids and/or delayed closure of sternum) was associated with occurrence of HAI in the univariate analysis (odds ratio, 6.3; 95% confidence interval, 1.0-38.7; P = .037). CONCLUSIONS: Cardiopulmonary bypass induces a profound decrease in mHLA-DR expression in young infants. Among patients with higher postoperative severity, low level of mHLA-DR in the early postoperative period is associated with the development of HAI.