Altered phenotype and functionality of circulating immune cells characterize adult patients with nonalcoholic steatohepatitis

Nonalcoholic steatohepatitis (NASH) is a chronic inflammatory liver disease associated with insulin resistance and its metabolic consequences. Leukocyte mobilization, intrahepatic activation, and an exacerbated production of reactive oxygen species (ROS) and cytokines contribute to the development of NASH. Though alterations in peripheral blood (PB) T cell proportions and functionality remain unidentified, they might play a main role in NASH progression. We have compared the phenotype and Th1/Th2 commitment of peripheral immune cell reservoirs in adult patients and controls as well as the ability of neutrophils and monocytes to handle an ex vivo challenge. Also, we correlated those parameters with the main histological characteristics in NASH. Compared with controls, patients showed increased numbers of CD4⁺ cells and both CD4⁺ and CD8⁺ CD45RO subsets together with a higher frequency of IFN-γ-producing CD4⁺ and CD8⁺ T cells. We also found a decreased number of CD4⁺ and CD8⁺ CD45RA subsets. The distinctive production of IFN-γ highlights the significance of the observed skewed frequencies of PB T cells. Whereas ROS production by monocytes from NASH patients did not differ from controls, circulating neutrophils displayed a particularly higher phorbol myristate acetate-induced production of ROS. A negative correlation between oxidative burst and fibrosis grade was observed. This study reveals the presence of a characteristic profile of peripheral immune cells in NASH. We also discuss the probable influence of obesity on some of our present findings.     

Etanercept Downregulates the Th17 Pathway and Decreases the IL-17+/IL-10+ Cell Ratio in Patients with Psoriasis Vulgaris

Purpose

To evaluate circulating and lesional CD4⁺ and CD8⁺ cells belonging to Th1, Th2, and Th17 patterns as well as IL-10⁺ cells before and after a 12-week lasting course with etanercept or acitretin in patients with psoriasis.

Methods

15 patients were given etanercept 50 mg twice weekly and 15 patients acitretin 0,4 mg/kg/day, both for 12 weeks. At the baseline and at the end of the treatment, blood and skin samples were taken to investigate IL-4, IL-8, IL-10, IL-17, and IFN-γ-producing CD4⁺ and CD8⁺ cells. As controls, 10 healthy controls (HC) and 6 atopic dermatitis (AD) patients were included into the study.

Results

Psoriasis patients showed augmented IL-17- and IL-8-producing CD4⁺ cells in the blood than HC and AD patients. In the skin lesions, IL-17⁺ cells were more represented in psoriasis than in AD, while the number of IL-4-producing cells was reduced in psoriasis patients than in AD ones. Etanercept was able to significantly reduce the number of IL-17- and IL-8-producing CD4⁺ and CD8⁺ cells both in skin and blood, as well as to augment the proportion of IL-10-producing CD4⁺ cells in the skin of psoriatic patients, while acitretin was not.

Conclusions

Our results confirmed the role of Th17 cells in the pathogenesis of psoriasis. Etanercept, but not acitretin, was able to downregulate the Th17 pathway and to increase the percentages of IL-10-producing cells in the skin.     

SV-IV Peptide1–16 reduces coagulant power in normal Factor V and Factor V Leiden

Background

Alefacept (anti-CD2) biological therapy selectively targets effector memory T cells (Tem) in psoriasis vulgaris, a model Type 1 autoimmune disease.

Methods

Circulating leukocytes were phenotyped in patients receiving alefacept for moderate to severe psoriasis.

Results

In all patients, this treatment caused a preferential decrease in effector memory T cells (CCR7^- CD45RA^-) (mean 63% reduction) for both CD4⁺ and CD8⁺ Tem, while central memory T cells (Tcm) (CCR7⁺CD45RA^-) were less affected, and naïve T cells (CCR7⁺CD45RA⁺) were relatively spared. Circulating CD8⁺ effector T cells and Type 1 T cells (IFN-γ-producing) were also significantly reduced.

Conclusion

Alefacept causes a selective reduction in circulating effector memory T cells (Tem) and relative preservation of central memory T cells (Tcm) in psoriasis.     

Elevated Double Negative T Cells in Pediatric Autoimmunity

Purpose

Autoimmune diseases are thought to be caused by a loss of self-tolerance of the immune system. One candidate marker of immune dysregulation in autoimmune disease is the presence of increased double negative T cells (DNTs) in the periphery. DNTs are characteristically elevated in autoimmune lymphoproliferative syndrome, a systemic autoimmune disease caused by defective lymphocyte apoptosis due to Fas pathway defects. DNTs have also been found in the peripheral blood of adult patients with systemic lupus erythematosus (SLE), where they may be pathogenic. DNTs in children with autoimmune disease have not been investigated.

Methods

We evaluated DNTs in pediatric patients with SLE, mixed connective tissue disease (MCTD), juvenile idiopathic arthritis (JIA), or elevated antinuclear antibody (ANA) but no systemic disease. DNTs (CD3⁺CD56^?TCRαβ⁺CD4^?CD8^?) from peripheral blood mononuclear cells were analyzed by flow cytometry from 54 pediatric patients including: 23 SLE, 15 JIA, 11 ANA and 5 MCTD compared to 28 healthy controls.

Results

Sixteen cases (29.6 %) had elevated DNTs (≥2.5 % of CD3⁺CD56^?TCRαβ⁺ cells) compared to 1 (3.6 %) control. Medication usage including cytotoxic drugs and absolute lymphocyte count were not associated with DNT levels, and percentages of DNTs were stable over time. Analysis of multiple phenotypic and activation markers showed increased CD45RA expression on DNTs from patients with autoimmune disease compared to controls.

Conclusion

DNTs are elevated in a subset of pediatric patients with autoimmune disease and additional investigations are required to determine their precise role in autoimmunity.     

B-Cell and T-Cell Phenotypes in CVID Patients Correlate with the Clinical Phenotype of the Disease

Background

Common variable immunodeficiency (CVID) is a heterogeneous disorder characterized by recurrent infections and defective immunoglobulin production.

Methods

The DEFI French national prospective study investigated peripheral T-cell and B-cell compartments in 313 CVID patients grouped according to their clinical phenotype, using flow cytometry.

Results

In patients developing infection only (IO), the main B-cell or T-cell abnormalities were a defect in switched memory B cells and a decrease in naive CD4⁺ T cells associated with an increase in CD4⁺CD95⁺ cells. These abnormalities were more pronounced in patients developing lymphoproliferation (LP), autoimmune cytopenia (AC), or chronic enteropathy (CE). Moreover, LP and AC patients presented an increase in CD21^low B cells and CD4⁺HLA-DR⁺ T cells and a decrease in regulatory T cells.

Conclusion

In these large series of CVID patients, the major abnormalities of the B-cell and T-cell compartments, although a hallmark of CVID, were only observed in half of the IO patients and were more frequent and severe in patients with additional lymphoproliferative, autoimmune, and digestive complications.     

Age-related accumulation of T cells with markers of relatively stronger autoreactivity leads to functional erosion of T cells

Background

Although it is known that regulatory T cells (Tregs) can suppress the function of effector T cells, and may contribute to impaired immune response, the precise role of Tregs during the course of hepatitis B virus (HBV) infection remains to be elucidated. A newly identified subset of the CD4⁺Foxp3⁺ Tregs, the CD39⁺ Tregs, has been associated with viral infections and autoimmune diseases. Therefore, we hypothesized that this discrete Treg subset may contribute to the chronic infection of HBV.

Results

Initial characterization studies of healthy peripheral CD39⁺FoxP3⁺CD4⁺ T cells revealed that the majority were CD45RA^- Treg cells. Subsequent analysis of HBV-infected patients (38 asymptomatic HBV carriers (AsCs), 37 chronic active hepatitis B (CAH), 29 HBV-associated acute-on-chronic liver failure (ACLF)) and healthy individuals (25 controls) was conducted to assess association with HBV copy number and the liver injury marker alanine aminotransferase (ALT). A higher percentage of CD39⁺ Tregs was detected within the population of FoxP3⁺CD4⁺ T cells in peripheral blood of AsCs patients. Moreover, the percentage of CD39⁺ Tregs was significantly less in CAH and ACLF patients. The increased proportions of circulating CD39⁺ Tregs were positively correlated with serum viral load, but inversely correlated with serum ALT level.

Conclusion

These findings not only suggest that CD39⁺ Treg cells may be involved in HBV disease progression but also identify CD39⁺ Tregs as a dynamic immune regulatory cell population that may represent a new target of immunomodulatory therapeutic interventions.     

Combined use of etanercept and MTX restores CD4+/CD8+ ratio and Tregs in spleen and thymus in collagen-induced arthritis

Objective

To further explore the mechanism of etanercept (ENT, rhTNFR:Fc) and methotrexate (MTX) in the combined treatment of rheumatoid arthritis (RA), we investigated whether thymic and splenic T-cell subsets and their related cytokines imbalance could be restored by ETN/MTX treatment.

Methods

The effect of ETN/MTX on collagen-induced arthritis (CIA) was evaluated by arthritis scores, joint and spleen histopathology, as well as indices of thymus and spleen. T lymphocytes proliferation was determined by [³H]-TdR incorporation. Levels of TNF-α, LT-α, IL-1β, RANKL, IL-10, IL-17, IFN-γ and IL-6 were detected by enzyme linked immunosorbent assay. The subsets of T lymphocytes including CD4⁺, CD8⁺, CD3⁺CD4⁺, CD4⁺CD25⁺, CD4⁺CD62L⁺ and CD4⁺CD25⁺Foxp3⁺ cells were quantified using flow cytometry.

Results

Combined administration of ETN/MTX significantly inhibited the proliferation of T lymphocytes, decreased serum IL-6, TNF-α, IL-1β, RANKL and macrophage supernatant IL-17, LT-α, increased serum IFN-γ and macrophage supernatant IL-10. Moreover, the combined administration could restore CD4⁺/CD8⁺ ratio and Treg cells of CIA thymus and spleen.

Conclusion

Taken together, our findings suggest that ENT/MTX may modify the abnormal T lymphocytes balance from central to peripheral lymphoid organs, which may partially, explained the mechanism of the combined administration.     

Transient T cell depletion causes regression of melanoma metastases

Background

Cognate immunity against neoplastic cells depends on a balance between effector T cells and regulatory T (Treg) cells. Treg cells prevent immune attack against normal and neoplastic cells by directly suppressing the activation of effector CD4⁺ and CD8⁺ T cells. We postulated that a recombinant interleukin 2/diphtheria toxin conjugate (DAB/IL2; Denileukin Diftitox; Ontak) may serve as a useful strategy to deplete Treg cells and break tolerance against neoplastic tumors in humans.

Methods

We administered DAB/IL2 (12 μg/kg; four daily doses; 21 day cycles) to 16 patients with metastatic melanoma and measured the effects on the peripheral blood concentration of several T cell subsets and on tumor burden.

Results

We found that DAB/IL2 caused a transient depletion of Treg cells as well as total CD4⁺ and CD8⁺ T cells (< 21 days). T cell repopulation coincided with the de novo appearance of melanoma antigen-specific CD8⁺ T cells in several patients as determined by flow cytometry using tetrameric MART-1, tyrosinase and gp100 peptide/MHC conjugates. Sixteen patients received at least one cycle of DAB/IL2 and five of these patients experienced regressions of melanoma metastases as measured by CT and/or PET imaging. One patient experienced a near complete response with the regression of several hepatic and pulmonary metastases coupled to the de novo appearance of MART-1-specific CD8⁺ T cells. A single metastatic tumor remained in this patient and, after surgical resection, immunohistochemical analysis revealed MART1⁺ melanoma cells surrounded by CD8⁺ T cells.

Conclusion

Taken together, these data indicate that transient depletion of T cells in cancer patients may disrupt the homeostatic control of cognate immunity and allow for the expansion of effector T cells with specificity against neoplastic cells. Several T cell depleting agents are clinically available and this study provides strong rationale for an examination of their efficacy in cancer patients.

Trial registration

NCT00299689 (ClinicalTrials.gov Identifier).     

Changes of Treg-Associated Molecules on CD4+CD25+Treg Cells in Myasthenia Gravis and Effects of Immunosuppressants

Objective

Myasthenia gravis (MG) is a CD4⁺ T cell-dependent autoimmune disease, and close attention has been paid to the role of CD4⁺CD25⁺Treg cells (Tregs). Previous results regarding Tregs in MG patients have been conflicting. The discrepancy was partly ascribed to selecting different Treg-associated molecules in defining Tregs. Therefore, we considered it necessary to find a reliable index for assessing the immunologic state in MG patients and explore the effect of IS on them.

Methods

We adopted flow cytometric techniques to measure the numbers and frequencies of Tregs in peripheral blood taken from 57 patients and 91 age-matched healthy donors, and we also analyzed FOXP3 mean fluorescence intensity on Tregs.

Results

The number and frequency of Tregs in peripheral blood of MG patients significantly decreased, together with down-regulation of FOXP3 expression. There was dynamic change of Treg cell level and the inverse relationship with clinical symptom, suggesting that the immunologic disorder in MG patients was related to peripheral Tregs population. Meanwhile, CD4⁺CD25⁺FOXP3⁺Helios⁺T cells might be activated Tregs, rather than nTregs. Moreover, the number and frequency of CD4⁺CD25⁺FOXP3⁺Helios⁺T cells significantly decreased in MG patients, indicating that the reduction of the activated Tregs population might be a critical contributor to the pathogenesis of MG.

Conclusions

The significant reduction of the peripheral Tregs population in MG patients might be responsible for the immunologic disorders in MG patients. IS such as GC took its effect possible by increasing the population size, and the underlying mechanism should be further investigated.     

Persistence of a Large Population of Exhausted Monoclonal B cells in Mixed Cryoglobuliemia After the Eradication of Hepatitis C Virus Infection

Purpose

Functionally exhausted and mostly autoreactive B-cells with a peculiar CD21^lowCD11c⁺ phenotype accumulate in several human immunological disorders including common variable immunodeficiency, HIV infection and rheumatoid arthritis. In HCV-associated mixed cryoglobulinemia (MC) there is accumulation of exhausted clonal B cells expressing a V_H1-69-encoded cross-reactive idiotype; these cells are phenotypically heterogeneous, displaying either a CD21^lowCD11c⁺ or a marginal zone (MZ)-like (IgM⁺CD27⁺CD21⁺CD11c^-) phenotype. Irrespective of their phenotype, V_H1-69⁺ B-cells are unresponsive to the stimulation of Toll-like receptor 9 (TLR9). We investigated the fate of these cells after the eradication of HCV.

Methods

Fourteen MC patients were studied before and after antiviral therapy. V_H1-69⁺ B-cells were identified using the G6 monoclonal antibody and their phenotype and responsiveness to the stimulation of TLR9 were investigated.

Results

In seven virological non-responders, cryoglobulin levels and the number and phenotype of V_H1-69⁺ B cells remained substantially unchanged. By contrast, in sustained viral responders cryoglobulinemia subsided and the number of V_H1-69⁺ B cells declined. However, high proportions of MZ-like V_H1-69⁺ B cells retaining unresponsiveness to TLR9 stimulation persisted for several months in these patients.

Conclusions

Clonal expansion of CD21^low V_H1-69⁺ B cells may depend on continual stimulation by HCV, whereas their MZ-like counterparts may persist for years after the eradication of infection. Prolonged survival of exhausted MZ-like B cells after withdrawal of the initial inciting stimulus may contribute to the accumulation of autoreactive B cells in immunological disorders.     

Maturation of CD4+ Regulatory T Lymphocytes and of Cytokine Secretions in Infants Born Prematurely

Purpose

To characterize the maturation of CD4⁺ regulatory T lymphocytes (Treg) and of cytokine productions in preterm infants during their first 16 months of life.

Methods

The proportions of CD4⁺ Treg cells, their phenotypic characteristics, and the mitogen-induced cytokine productions by peripheral blood mononuclear cells (PBMC) were analysed in 26 very-preterm infants from 2 to 16 months of age, and compared to results obtained for 17 cord blood mononuclear cells (CBMC) from very-preterm infants, 12 from term infants and to blood samples from 40 adults.

Results

High proportion of CD25^+/highCD4⁺ Treg cells was found at birth in preterm CB with a gradual decreased afterwards. However, their percentage at 16 months of age was still higher than in term CB. In contrast to adults, preterm infants were characterized by excellent linear correlations between the proportions of CD25^+/highCD4⁺ and CD25^+/highFoxP3⁺ CD4⁺ or CD25^+/highCD127^low CD4⁺ or CD25^+/highFoxP3⁺CD127^low CD4⁺T lymphocytes. CD45RO⁺ and HLA-DR⁺ expressions were very low on preterm Treg and progressively increased with age. Functionally, preterm compared to term CBMC secreted in response to phytohaemagglutinin lower IFN-γ, higher IL-5 and similar IL-12p70, IL-10, IL-2 and IL-13 concentrations. IFN-γ, IL-12p70 and IL-10 productions were at 16 months still lower than those obtained for adults

Conclusion

Preterm differed from term CBMC both by their proportion and phenotype of CD4⁺ Treg lymphocytes and by their cytokine secretions. Maturation occurred during infancy with similar IFN-γ secretion but with persistently higher proportion of CD4⁺ Treg cells in 1 year preterm infants compared to term neonates.     

T cell Activation does not drive CD4 decline in longitudinally followed HIV-infected Elite Controllers

Background

Elite controllers (EC) are a rare subset of HIV infected individuals who control viral load below 50 copies/ml of plasma without treatment.

Methods

Thirty four EC were studied. The slope of CD4 count change was available for 25 of these subjects. We assessed immune activation by measuring the percent of CD38⁺HLA-DR⁺CD8⁺ T cells in the EC group and comparing it with that in 24 treatment-naïve HIV disease progressors and 13 HIV uninfected healthy controls.

Results

Compared to HIV uninfected subjects, EC had higher percentages of CD38⁺HLA-DR⁺CD8⁺ T cells (p < 0.001) that was lower than that observed in progressors (p < 0.01). Fifteen of 25 EC had a slope of CD4 count change that was not significantly different from 0 while 3 had a positive and 7 a negative CD4 count slope. Immune activation did not distinguish EC subsets with stable/increasing versus declining CD4 counts.

Conclusions

Elevated immune activation in ECs is not associated with a faster rate of CD4 decline     

Associations of T helper 1, 2, 17 and regulatory T lymphocytes with mortality in severe sepsis

Objective and design

T helper 17 (Th17) and regulatory T (T_reg) lymphocytes might play important roles in patients with severe sepsis. The association of Th17 or T_reg lymphocytes with survival is also unclear.

Methods

Eighty-seven patients with severe sepsis were enrolled from our intensive care units between August 2008 and July 2010. Leukocyte antigens and clinical data were determined on day 1 in all patients and on day 7 in first-year patients.

Results

The percentages in peripheral blood mononuclear cells (PBMCs) and circulatory counts of CD4⁺ and CD8⁺ lymphocytes in survivors were higher than those in non-survivors. Th1/CD4⁺ ratios and circulatory Th1 lymphocyte counts in survivors were higher than in non-survivors. Absolute counts of Th17 and T_reg lymphocytes in survivors were higher than in non-survivors. The percentages of CD4⁺ and CD8⁺ in survivors’ PBMCs were increased after 6 days. Th17/CD4⁺ ratios and circulatory Th17 lymphocyte counts in survivors were increased after 6 days.

Conclusions

Higher Th1 differentiation and total CD4⁺ T lymphocyte counts were associated with higher survival. The association of circulatory Th17 and T_reg lymphocytes with mortality in severe sepsis may be due to the change in total CD4⁺ T lymphocytes. In survivors, Th17 differentiation and counts were restored.     

Phenotype, functions and fate of adoptively transferred tumor draining lymphocytes activated ex vivo in mice with an aggressive weakly immunogenic mammary carcinoma

Background

Regression of established tumors can be induced by adoptive immunotherapy with tumor draining lymph node lymphocytes activated with bryostatin and ionomycin. We hypothesized that tumor regression is mediated by a subset of the transferred T lymphocytes, which selectively infiltrate the tumor draining lymph nodes and proliferate in vivo.

Results

Adoptive transfer of B/I activated tumor draining lymphocytes induces regression of advanced 4T1 tumors, and depletion of CD8, but not CD4 T cells, abrogated tumor regression in mice. The predominant mediators of tumor regression are CD8+ and derived from CD62L^- T cells. Transferred lymphocytes reached their peak concentration (10.5%) in the spleen 3 days after adoptive transfer and then rapidly declined. Adoptively transferred cells preferentially migrated to and/or proliferated in the tumor draining lymph nodes, peaking at day 5 (10.3%) and remained up to day 28. CFSE-stained cells were seen in tumors, also peaking at day 5 (2.1%). Bryostatin and ionomycin-activated cells proliferated vigorously in vivo, with 10 generations evident in the tumor draining lymph nodes on day 3. CFSE-stained cells found in the tumor draining lymph nodes on day 3 were 30% CD8⁺, 72% CD4⁺, 95% CD44⁺, and 39% CD69⁺. Pre-treatment of recipient mice with cyclophosphamide dramatically increased the number of interferon-gamma producing cells.

Conclusions

Adoptively transferred CD8+ CD62L^low T cells are the principal mediators of tumor regression, and host T cells are not required. These cells infiltrate 4T1 tumors, track preferentially to tumor draining lymph nodes, have an activated phenotype, and proliferate in vivo. Cyclophosphamide pre-treatment augments the anti-tumor effect by increasing the proliferation of interferon-gamma producing cells in the adoptive host.     

Elevated Th22 Cells Correlated with Th17 Cells in Patients with Rheumatoid Arthritis

Background

T-helper (Th) 22 and Th17 cells are implicated in the pathogenesis of autoimmune diseases. The roles of Th22 cells in the pathophysiology of rheumatoid arthritis (RA) remain unsettled.

Materials and Methods

CD4⁺IFN??^?IL17^?IL-22⁺ T cells (Th22 cells), CD4⁺IFN??^?IL-22^?IL17⁺ T cells (pure Th17 cells), CD4⁺IL17⁺ T cells (Th17 cells), and CD4⁺IFN??⁺ T cells (Th1 cells) in RA, osteoarthritis patients, and healthy controls were examined by flow cytometry. Plasma IL-22 and IL-17 levels were examined by enzyme-linked immunosorbent assay.

Results

Th22 cells, pure Th17 cells, Th17 cells, and interleukin-22 were significantly elevated in RA patients compared with osteoarthritis and healthy controls, but there were no significant differences regarding Th1 cells and interleukin-17. Th22 cells showed a positive correlation with interleukin-22 as well as pure Th17 cells or Th17 cells in RA patients. Additionally, the percentages of Th22 cells, pure Th17 cells as well as Th17 cells correlated positively with both C-reactive protein levels and 28-joints disease activity score.

Conclusion

Together, our results indicated a possible role of Th22 pure Th17 cells and Th17 cells in RA, and blockade of the interleukin-22 may be a reasonable therapeutic strategy for RA.     

Decreased arthritis severity in cathepsin L-deficient mice is attributed to an impaired T helper cell compartment

Objective

Cathepsin L (CL) is potentially involved in joint destruction and in antigen presentation in rheumatoid arthritis. In order to define the roles of this protease in arthritis development we analysed the antigen-induced arthritis (AIA) in CL-deficient (CL^?/?) mice.

Methods

Antigen-induced arthritis was induced in CL^?/? and wild-type mice. Complete CL deficiency resulted in an impaired positive selection of conventional CD4⁺ T helper (Th) cells and finally in a reduced number of Th cells. Thus, we addressed the effect of this phenotype by rescuing CD4⁺ Th cell numbers by transgenic expression of the human CL-like protease cathepsin V (hCV) in thymic epithelium of CL^?/? mice [Tg(K14-hCV);CL^?/?]. The arthritis development was monitored by measuring joint swelling. Joint inflammation and destruction were assessed histopathologically.

Results

The severity of AIA was decreased in CL^?/? mice characterized by reduced swelling, decreased inflammation and destruction, and diminished cellular and humoral immune responsiveness. AIA in Tg(K14-hCV);CL^?/? mice was associated with a reconstitution of all parameters by normalization of the ratio of regulatory to conventional T cells.

Conclusions

Cathepsin L has a significant impact on AIA severity by influencing the selection of Th cell populations in the thymus, but seems not play any significant role in the direct joint destruction.     

Decreased Levels of Circulating CD4+CD25+Foxp3+ Regulatory T Cells in Patients with Primary Antiphospholipid Syndrome

Introduction

CD4⁺CD25⁺Foxp3⁺ regulatory T (Treg) cell dysfunction has been documented in various autoimmune disorders, but not in antiphospholipid syndrome (APS) so far.

Methods

In this cross-sectional study, we aim to investigate CD4⁺CD25⁺Foxp3⁺ Treg cells, CD3⁺CD19^? T cells and CD3^?CD19⁺ B cells in patients with primary APS and healthy controls. Cell subtypes were immunophenotyped using specific monoclonal antibodies (anti-CD3 CY5, anti-CD4 FITC, anti-CD25, anti-Foxp3, anti-CD19 PE) and flow cytometry.

Results

Twenty patients with APS and 20 age- and sex-matched controls were studied. The percentage of total lymphocytes, activated Th cells (CD4+CD25+), Treg cells and CD3^?CD19⁺ B cells were found significantly lower in APS patients as compared to controls (all p?<?0.05).

Conclusion

A dysfunction in CD4⁺CD25⁺Foxp3⁺ Treg cells may represent one of the mechanisms leading to autoimmunity in APS patients. The decreased number of CD3^?CD19⁺ B cells of APS patients warrants further elucidation.     

Circulating T Cells of Patients with Nijmegen Breakage Syndrome Show Signs of Senescence

Purpose

The Nijmegen breakage syndrome (NBS) is an inherited genetic disorder characterized by a typical facial appearance, microcephaly, growth retardation, immunodeficiency, and a strong predisposition to malignancies, especially of lymphoid origin. NBS patients have a mutation in the NBN gene which involves the repair of DNA double-strand breaks (DSBs). Here we studied the peripheral T cell compartment of NBS patients with a focus on immunological senescence.

Methods

The absolute numbers and frequencies of the different T cell subsets were determined in NBS patients from young age till adulthood and compared to age-matched healthy individuals (HI). In addition, we determined the expression of senescent T cell markers and the signal joint T cell receptor excision circles (sjTRECs) content.

Results

Our results demonstrate that NBS patients have reduced T cell numbers. NBS patients showed lower numbers of αβ⁺ T cells, but normal γδ⁺ T cell numbers compared to HI. Concerning the αβ⁺ T cells, both CD4⁺ as well as CD8⁺ T cells were excessively reduced in numbers compared to aged-matched HI. In addition, NBS patients showed higher frequencies of the more differentiated T cells expressing the senescent cell marker CD57 and did not express co-stimulatory molecule CD28. These effects were already present in the youngest age group. Furthermore, NBS patients showed lower sjTREC content in their T cells possibly indicative of a lower thymic output.

Conclusions

We conclude that circulating T cells from NBS patients show signs of a senescent phenotype which is already present from young age on and which might explain their T cell immune deficiency.