T-cell Blasts Research Articles

Dendritic cell ICAM-1 strengthens synapses with CD8 T cells but is not required for their early differentiation

Lymphocyte priming in lymph nodes (LNs) was postulated to depend on the formation of stable Tcell receptor (TCR)-specific immune synapses (ISs) with antigen (Ag)-presenting dendritic cells (DCs). The high-affinity LFA-1 ligand ICAM-1 was implicated in different ISs studied invitro. We dissect the invivo roles of endogenous DC ICAM-1 in Ag-stimulated Tcell proliferation and differentiation and find that under type 1 polarizing conditions in vaccinated or vaccinia virus-infected skin-draining LNs, Ag-presenting DCs engage in ICAM-1-dependent stable conjugates with a subset of Ag-specific CD8 blasts. Nevertheless, in the absence of these conjugates, CD8 lymphocyte proliferation and differentiation into functional cytotoxic Tcells (CTLs) and skin homing effector lymphocytes takes place normally. Our results suggest that although CD8 Tcell blasts engage in tight ICAM-1-dependent DC-T ISs, firm ISs are dispensable for TCR-triggered proliferation and differentiation into productive effector lymphocytes.

TCF3 haploinsufficiency defined by immune, clinical, gene-dosage, and murine studies

TCF3 is a transcription factor contributing to early lymphocyte differentiation. Germline monoallelic dominant negative and biallelic loss-of-function (LOF) null TCF3 mutations cause a fully penetrant severe immunodeficiency. We identified 8 individuals from 7 unrelated families with monoallelic LOF TCF3 variants presenting with immunodeficiency with incomplete clinical penetrance. We sought to define TCF3 haploinsufficiency (HI) biology and its association with immunodeficiency. Patient clinical data and blood samples were analyzed. Flow cytometry, Western blot analysis, plasmablast differentiation, immunoglobulin secretion, and transcriptional activity studies were conducted on individuals carrying TCF3 variants. Mice with a heterozygous Tcf3 deletion were analyzed for lymphocyte development and phenotyping. Individuals carrying monoallelic LOF TCF3 variants showed B-cell defects (eg, reduced total, class-switched memory, and/or plasmablasts) and reduced serum immunoglobulin levels; most but not all presented with recurrent but nonsevere infections. These TCF3 LOF variants were either not transcribed or translated, resulting in reduced wild-type TCF3 protein expression, strongly suggesting HI pathophysiology for the disease. Targeted RNA sequencing analysis of T-cell blasts from TCF3-null, dominant negative, or HI individuals clustered away from healthy donors, implying that 2 WT copies of TCF3 are needed to sustain a tightly regulated TCF3 gene-dosage effect. Murine TCF3 HI resulted in a reduction of circulating Bcells but overall normal humoral immune responses. Monoallelic LOF TCF3 mutations cause a gene-dosage-dependent reduction in wild-type protein expression, B-cell defects, and a dysregulated transcriptome, resulting in immunodeficiency. Tcf3+/- mice partially recapitulate the human phenotype, underscoring the differences between TCF3 in humans and mice.

Lineage reprogramming of human adipose mesenchymal stem cells to immune modulatory i-Heps.

Pluripotent stem cell derived-hepatocytes depict fetal -hepatocyte characteristics/maturity and are immunogenic limiting their applications. Attempts have been made to derive hepatocytes from mesenchymal stem cells using developmental cocktails, epigenetic modulators and small molecules. However, achieving a stable terminally differentiated functional state had been a challenge. Inefficient hepatic differentiation could be due to lineage restrictions set during development. Hence a novel lineage reprogramming approach has been utilized to confer competence to adipose-mesenchymal stem cells (ADMSCs) to efficiently respond to hepatogenic cues and achieve a stable functional hepatic state. Lineage reprogramming involved co-transduction of ADMSCs with hepatic endoderm pioneer Transcription factor (TF)-FOXA2, HHEX-a homeobox gene and HNF4α-master TF indispensable for hepatic state maintenance. Lineage priming was evidenced by endogenous HFN4α promoter demethylation and robust responsiveness to minimal hepatic maturation cues. Induced hepatocytes (i-Heps) exhibited mesenchymal-to-epithelial transition and terminal hepatic signatures. Functional characterisation of i-Heps for hepatic drug detoxification systems, xenobiotic uptake/clearance, metabolic status and hepatotropic virus entry validated acquisition of stable hepatic state and junctional maturity Exhaustive analysis of MSC memory in i-Heps indicated loss of MSC-immunophenotype and terminal differentiation to osteogenic/adipogenic lineages. Importantly, i-Heps suppressed phytohemagglutinin-induced T-cell blasts, inhibited allogenic mixed-lymphocyte reactions (MLRs) and secreted immunomodulatory- indoleamine 2,3-dioxygenase in T-cell blast co-cultures akin to native ADMSCs. In a nutshell, the present study identifies a novel cocktail of TFs that reprogram ADMSCs to stable hepatic state. i-Heps exhibit adult hepatocyte functional maturity with robust immune-modulatory abilities rendering suitability for rigorous drug testing, hepatocyte-pathogen interaction studies and transplantation in allogenic settings.

The PI-3-Kinase P110α Catalytic Subunit of T Lymphocytes Modulates Collagen-Induced Arthritis.

The phosphatidylinositol 3-kinase (PI3K) family of enzymes plays a determinant role in inflammation and autoimmune responses. However, the implication of the different isoforms of catalytic subunits in these processes is not clear. Rheumatoid arthritis (RA) is a chronic, systemic autoimmune inflammatory disease that entails innate and adaptive immune response elements in which PI3K is a potential hub for immune modulation. In a mouse transgenic model with T-cell-specific deletion of p110α catalytic chain (p110α−/−ΔT), we show the modulation of collagen-induced arthritis (CIA) by this isoform of PI3K. In established arthritis, p110α−/−ΔT mice show decreased prevalence of illness than their control siblings, higher IgG1 titers and lower levels of IL-6 in serum, together with decreased ex vivo Collagen II (CII)-induced proliferation, IL-17A secretion and proportion of naive T cells in the lymph nodes. In a pre-arthritis phase, at 13 days post-Ag, T-cell-specific deletion of p110α chain induced an increased, less pathogenic IgG1/IgG2a antibodies ratio; changes in the fraction of naive and effector CD4+ subpopulations; and an increased number of CXCR5+ T cells in the draining lymph nodes of the p110α−/−ΔT mice. Strikingly, T-cell blasts in vitro obtained from non-immunized p110α−/−ΔT mice showed an increased expression of CXCR5, CD44 and ICOS surface markers and defective ICOS-induced signaling towards Akt phosphorylation. These results, plus the accumulation of cells in the lymph nodes in the early phase of the process, could explain the diminished illness incidence and prevalence in the p110α−/−ΔT mice and suggests a modulation of CIA by the p110α catalytic chain of PI3K, opening new avenues of intervention in T-cell-directed therapies to autoimmune diseases.

T‐cell blast crisis of chronic myelogenous leukemia presented with coexisting p210 and p190 BCR‐ABL transcripts and t(10;11)(q11;p15)

BackgroundBlast transformation of chronic myelogenous leukemia (CML) to T lymphoblastic lymphoma/acute lymphoblastic leukemia (T‐LBL/ALL) is rare, and the molecular mechanism is still unclear.Case reportA 28‐year‐old woman who developed T‐ALL with coexpressing both p210 and p190 BCR‐ABL transcripts five years after the initial diagnosis of CML in chronic phase. The proliferation of bone marrow was extremely active with blast cells over 20%. Chromosome analysis revealed t(9;22)(q34;q11) and t(10;11)(q25;p15). Flow immunophenotyping showed that blasts expressed CD4, CD7, CD11b, CD38, CD34, CD33, and cCD3.ConclusionIt is the first T‐cell blast of CML case with coexisting p210 and p190 as well as additional chromosome translocations. Through review this case and previous reports, we will reveal that CML patients with T‐lymphocyte transformation depend on potential molecular and pathological mechanism.

Haploinsufficiency of A20 with a novel mutation of deletion of exons 2–3 of TNFAIP3

Objectives Haploinsufficiency of A20 (HA20) due to loss-of-function mutations of TNFAIP3 leads to an autoinflammatory disease. These mutations produce a premature termination codon in most cases of HA20. However, exon deletion has not been reported. Methods Genomic DNA was extracted from the peripheral blood of the patient clinically suspected of HA20. We examined autoinflammatory disease-causing genes and performed a multiplex ligation-dependent probe amplification (MLPA) assay for copy number analysis. Next, to determine the disconnection point, genomic DNA was amplified with long-range PCR and sequenced. Finally, western blotting was carried out to measure A20 protein expression in mitogen phytohaemagglutinin (PHA)-induced T-cell blasts from the patient and a healthy volunteer. Results Targeted next-generation sequencing found no pathogenic mutation, but copy number variation (CNV) analysis suggested a heterozygous deletion of exons 2–3. The MLPA assay and long-range PCR confirmed the mutation. Western blotting analysis indicated a marked decrease in expression of A20 protein from the patient compared to a normal control. The results showed that this deletion was a pathogenic mutation. Conclusion This study demonstrates a novel mutation resulting in a deletion of exons 2–3 of TNFAIP3. MLPA analysis is a useful initial screening method for HA20 patients.

Correlation Between Extended Leukocyte Differential Count and Coronary Artery Disease.

Leukocyte count is closely associated with the risk of coronary artery disease (CAD). Levels of leukocyte subpopulations in patients with CAD, however, remain largely unknown. In this study, we compared the distributions and counts of 16 leukocyte subpopulations between 40 patients with CAD and 40 healthy controls using the CytoDiff flow cytometric system. Our results demonstrated significant increases in the frequencies and counts of all monocytes, immature granulocytes, and B-lymphocytes in patients with CAD, suggesting that the levels of these leukocyte subpopulations may serve as potential biomarkers for diagnosis of CAD. By contrast, the levels of cytotoxic T/natural killer lymphocytes were markedly decreased in patients with CAD. In addition, the levels of T/natural killer lymphocytes, noncytotoxic T-lymphocytes, mature neutrophils, total neutrophils, eosinophils, basophils, and T-cell blasts in CAD patients with elevated levels of cardiac troponin I (cTnI), an independent indicator for poor prognosis in CAD, were significantly different from those in CAD patients with normal levels of cTnI. These data may help in the screening for biomarkers to discriminate between stable and unstable patients with CAD. Collectively, our results provide a detailed distribution profile of leukocyte subpopulations in patients with CAD and suggest their possible clinical application in predicting the risk and severity of CAD.

Effective “activated PI3Kδ syndrome”–targeted therapy with the PI3Kδ inhibitor leniolisib

AbstractPathogenic gain-of-function variants in the genes encoding phosphoinositide 3-kinase δ (PI3Kδ) lead to accumulation of transitional B cells and senescent T cells, lymphadenopathy, and immune deficiency (activated PI3Kδ syndrome [APDS]). Knowing the genetic etiology of APDS afforded us the opportunity to explore PI3Kδ inhibition as a precision-medicine therapy. Here, we report in vitro and in vivo effects of inhibiting PI3Kδ in APDS. Treatment with leniolisib (CDZ173), a selective PI3Kδ inhibitor, caused dose-dependent suppression of PI3Kδ pathway hyperactivation (measured as phosphorylation of AKT/S6) in cell lines ectopically expressing APDS-causative p110δ variants and in T-cell blasts derived from patients. A clinical trial with 6 APDS patients was conducted as a 12-week, open-label, multisite, within-subject, dose-escalation study of oral leniolisib to assess safety, pharmacokinetics, and effects on lymphoproliferation and immune dysregulation. Oral leniolisib led to a dose-dependent reduction in PI3K/AKT pathway activity assessed ex vivo and improved immune dysregulation. We observed normalization of circulating transitional and naive B cells, reduction in PD-1+CD4+ and senescent CD57+CD4− T cells, and decreases in elevated serum immunoglobulin M and inflammatory markers including interferon γ, tumor necrosis factor, CXCL13, and CXCL10 with leniolisib therapy. After 12 weeks of treatment, all patients showed amelioration of lymphoproliferation with lymph node sizes and spleen volumes reduced by 39% (mean; range, 26%-57%) and 40% (mean; range, 13%-65%), respectively. Thus, leniolisib was well tolerated and improved laboratory and clinical parameters in APDS, supporting the specific inhibition of PI3Kδ as a promising new targeted therapy in APDS and other diseases characterized by overactivation of the PI3Kδ pathway. This trial was registered at www.clinicaltrials.gov as #NCT02435173.

Aberrant Signaling Pathways in T-Cell Acute Lymphoblastic Leukemia.

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive disease caused by the malignant transformation of immature progenitors primed towards T-cell development. Clinically, T-ALL patients present with diffuse infiltration of the bone marrow by immature T-cell blasts high blood cell counts, mediastinal involvement, and diffusion to the central nervous system. In the past decade, the genomic landscape of T-ALL has been the target of intense research. The identification of specific genomic alterations has contributed to identify strong oncogenic drivers and signaling pathways regulating leukemia growth. Notwithstanding, T-ALL patients are still treated with high-dose multiagent chemotherapy, potentially exposing these patients to considerable acute and long-term side effects. This review summarizes recent advances in our understanding of the signaling pathways relevant for the pathogenesis of T-ALL and the opportunities offered for targeted therapy.

Missense variant in XYZ results in hyperactivation of mTOR signaling pathway and increased T-cell senescence

Abstract Phosphatidylinositol-4-phosphate 5-kinase I (XYZ) is a member of the class I PIP5K family that is responsible for the phosphorylation of phosphatidylinositol 4-phosphate (PIP) to produce phosphatidylinositol 4,5-biphosphate (PIP2). PIP2 is an important intermediate in the PI3K signaling pathway and is phosphorylated by PI3K to create phosphatidylinositol 3, 4, 5-triphosphate (PIP3), which is an important signaling molecule in TCR activation. Through whole exome sequencing, we have recently identified a 14-year old female Turkish patient with a homozygous missense variant in the activation loop of XYZ. The patient presents with lymphadenopathy, hemolytic anemia, low IgA, no IgE, positive antinuclear antibodies, and reactive airway disease. She has low naïve T-cells, increased CD45RA+ T-effector memory (TEMRA) cells, and increased CD57, a marker of T-cell senescence, on CD8+ T-cells. Patient T-cell blasts show increased phosphorylation of S6 levels upon TCR stimulation. Further, overexpression of mutant XYZ in T-cells resulted in increased phosphorylation of S6 at baseline compared to overexpression of wild type XYZ. Overall, these results suggest that the XYZ variant leads to hyperactivation of the mTOR signaling pathway, which may contribute to T-cell senescence and disease. This research was supported [in part] by the Intramural Research Program of the NIH, NIAID

Drug fever after a single dose of amoxicillin-clavulanic acid

Although amoxicillin-clavulanic acid (AMX/CLV) can be associated with hypersensitivity reactions, ranging from minor and self-limiting to anaphylaxis, this is the first reported case of a reproducible maculopapular exathema (MPE) with drug fever occurring after a single therapeutic dose, not associated with drug reaction with eosinophilia and systemic symptoms (DRESS). This case presented with delayed onset skin hypersensitivity reactions and fever that were finally associated with increased neutrophil counts plus high C-reactive protein (CRP) levels. The patient was a 14-year-old Caucasian girl with a history of AMX/CLV-associated reactions. In 2012, during an Epstein Barr virus infection, she had an MPE during AMX/CLV therapy. In February 2014, she was given AMX/CLV for a febrile bacterial infection and noted another itchy MPE 12 hours after the first dose. She stopped the drug, and in May 2014, she was referred to the Allergy Unit of Anna Meyer Children’s Hospital for evaluation. Skin tests were performed according to the European Network for Drug Allergy recommendations in the following sequence: (a) skin prick testing (SPT) with 20 mg/mL AMX and AMX/ CLV; and (b) an intradermal (ID) testing with 1/100 and 1/10 dilutions of the full-strength (200 mg/mL) AMX and AMX/CLV concentration at 20to 30-minute intervals. Positive and negative controls for SPT and ID were obtained using histamine (ALK-Abello, Milan, Italy: 10 and 1 mg/mL) and normal saline. A positive skin test result was when the SPT wheal was greater than 3 mm and was accompanied by erythema with a negative saline control result or when the ID was greater than 3 mm from the initial wheal or an increase in the diameter of the initial wheal was associated with a flare and a negative saline control result within 15 minutes. ID tests were also read after 24-72 hours for delayed T-cell-mediated reactions. Specific IgE to amoxicillin, ampicillin, and penicillin G and V were measured (Immunocap RAST, Uppsala, Sweden) and were all negative. Because all of the skin and in vitro tests were negative, an open challenge drug provocation test (DPT) to AMX/CLV using 1/ 10, 2/10, and then 7/10 of the therapeutic dose every 30 minutes (50/mg/kg/day in 2 doses) was administered following the current guidelines. She had no acute reactions, and after 2 hours of observation, she was discharged. After 3 hours from the last dose, she was vomiting and had a fever (39.4 C), headache, and generalized erythema. After 8 hours, she had diarrhea and difficulty sleeping. She was transported to the emergency department of Anna Meyer Children’s Hospital where her vital signs, complete blood count, and CRP levels were found to be within the normal range. She was discharged with the suspicion of a concurrent viral infection. In October 2014, the ID tests with AMX/CLAV were again negative. The DPT with AMX/CLV was repeated with the same graded challenge protocol, and after 3 hours, she again noted vomiting and had a fever, headache, and an itchy MPE. Later she had difficulty sleeping and diarrhea. The next day, she was admitted to the Anna Meyer Children’s Hospital Allergy Unit, where her blood was drawn and the following results were observed: 12.3 mg/mL CRP (normal value < 0.50 mg/dL); white blood cells count (WBC) of 14,950 mmc; neutrophils 90%; and liver function and a erythrocyte sedimentation rate within the normal ranges. After 2 days, the MPE was reduced and the girl no longer had a fever (Figure 1). After a month, a lymphocyte transformation test (LTT), induction of hapten-specific short-term T-cell lines, and cytokine production measurements were performed (see this article’s Online Repository at www.jaci-inpractice.org). The LTT was strongly positive to both AMX and AMX/CLV (Figure 2, A), and the T-cell lines that were specific for AMX and AMX/CLV could be induced. The LTT positivity and induction of the hapten-specific T-cell lines were also confirmed 6 months apart from the reaction (data not shown). A flow cytometric analysis showed high percentages of TNF-a producing T-cell blasts (Figure 2, B). No significant production of CXCL8, IL-6, or IL-17 could be found (data not shown). Drug fever is a rare event occurring in only approximately 3%-5% of adverse drug reactions. In 18%-29% of patients who

Lineage-specific function of Engrailed-2 in the progression of chronic myelogenous leukemia to T-cell blast crisis

In hematopoietic malignancies, oncogenic alterations interfere with cellular differentiation and lead to tumoral development. Identification of the proteins regulating differentiation is essential to understand how they are altered in malignancies. Chronic myelogenous leukemia (CML) is a biphasic disease initiated by an alteration taking place in hematopoietic stem cells. CML progresses to a blast crisis (BC) due to a secondary differentiation block in any of the hematopoietic lineages. However, the molecular mechanisms of CML evolution to T-cell BC remain unclear. Here, we have profiled the changes in DNA methylation patterns in human samples from BC-CML, in order to identify genes whose expression is epigenetically silenced during progression to T-cell lineage-specific BC. We have found that the CpG-island of the ENGRAILED-2 (EN2) gene becomes methylated in this progression. Afterwards, we demonstrate that En2 is expressed during T-cell development in mice and humans. Finally, we further show that genetic deletion of En2 in a CML transgenic mouse model induces a T-cell lineage BC that recapitulates human disease. These results identify En2 as a new regulator of T-cell differentiation whose disruption induces a malignant T-cell fate in CML progression, and validate the strategy used to identify new developmental regulators of hematopoiesis.

A Single Peptide-Major Histocompatibility Complex Ligand Triggers Digital Cytokine Secretion in CD4+ T Cells

We have developed a single-molecule imaging technique that uses quantum-dot-labeled peptide-major histocompatibility complex (pMHC) ligands to study CD4(+) Tcell functional sensitivity. We found that naive Tcells, Tcell blasts, and memory Tcells could all be triggered by a single pMHC to secrete tumor necrosis factor-α (TNF-α) and interleukin-2 (IL-2) cytokines with a rate of ∼1,000, ∼10,000, and ∼10,000 molecules/min, respectively, and that additional pMHCs did not augment secretion, indicating a digital response pattern. We also found that a single pMHC localized to the immunological synapse induced the slow formation of a long-lasting Tcell receptor (TCR) cluster, consistent with a serial engagement mechanism. These data show that scaling up CD4(+) Tcell cytokine responses involves increasingly efficient Tcell recruitment rather than greater cytokine production per cell.

KIR2DS1-dependent acquisition of CCR7 and migratory properties by human NK cells interacting with allogeneic HLA-C2+ DCs or T-cell blasts

AbstractNatural killer (NK) cells may capture the CCR7 chemokine receptor from allogeneic CCR7+ cells by trogocytosis and acquire migrating properties in response to lymph node chemokines. This event is negatively regulated by inhibitory killer Ig-like receptors (KIRs) and NKG2A. In this study, we analyzed the role of the HLA-C2–specific activating receptor KIR2DS1 in the process of CCR7 uptake by NK cells interacting with different allogeneic CCR7+ cells. Co-incubation of KIR2DS1+ fresh NK cells or NK-cell clones with HLA-C2+ CCR7+ lymphoblastoid cell lines resulted in increased CCR7 uptake. Remarkably, KIR2DS1 expression represented a major advantage for acquiring CCR7 from HLA-C2+ allogeneic dendritic cells (DCs) and T-cell blasts. These findings have important implications in haploidentical hematopoietic stem cell transplantation in which donor-derived (alloreactive) KIR2DS1+ NK cells, upon CCR7 acquisition, become capable of migrating toward lymph nodes, where they may kill patient DCs and T cells, preventing graft-versus-host and host-versus-graft reactions.

Neonatal hyperimmune T-cell reaction mimicking T-cell non-Hodgkin's lymphoma following BCG and hepatitis B co-vaccination

We describe a case of a 2-week-old male infant who presented with a rapidly enlarging inguinal mass after having received both the bacille Calmette-Guérin (BCG) and hepatitis B vaccines at birth. The clinical picture raised suspicion of a neoplasm, and an excision biopsy was performed. It showed complete effacement of the lymph node architecture by a diffuse proliferation of monomorphic, mitotically active, and medium-sized T-cell blasts with strong expression of CD99. Coalescent necrotizing granulomas were also seen. The lymph node culture was negative for BCG. Upon expert review and additional molecular diagnostics, the initial pathological diagnosis of lymphoblastic T-cell lymphoma was changed to ectopic BCG lymphadenitis and hyperimmune post-vaccinal reaction. The atypical T-cell proliferation was most likely a result of the adjuvant effects of the co-administered vaccines. Post-vaccinal reactions usually involve the injection site or result in localized lymph node enlargements in the areas draining the inoculation site. This case highlights the importance of the clinical context for accurate interpretation of the pathological findings. In the setting of post-vaccinal lymphadenopathy, a biopsy is rarely needed but, when performed, should be interpreted with great caution.

Natural killer cell function in women at high risk for HIV acquisition

To assess the role of natural killer (NK) cells in HIV acquisition. We conducted a nested case-control substudy to the Center for the AIDS Programme of Research in South Africa (CAPRISA004) tenofovir gel trial. Thirty women who acquired HIV infection (cases) and 30 women with high-risk sexual activity who remained HIV-negative (controls) were selected. Proliferation, degranulation and interferon-γ (IFNγ) secretion were measured by multiparametric flow cytometry after culture of recombinant human interleukin-2 (rhIL-2)-activated peripheral blood mononuclear cells with 721.221 cells or in-vitro HIV-infected, autologous CD4 T-cell blasts. Relationships between pre-acquisition NK cell responses and HIV acquisition were modeled with logistic regression models. NK cells from cases had lower IFNγ responses to human leukocyte antigen-deficient 721.221 cells than controls (median %IFNγposNK cells: 13.7 vs. 21.6%, P = 0.03). rhIL-2-activated NK cells from cases had responses to autologous HIV-infected target cells distinct from controls: cases had fewer proliferating and more frequent degranulating NK cells. NK cells from cases had significantly lower IFNγ responses to in-vitro HIV-infected autologous T cells than controls even after adjusting for responses to uninfected blasts (median %IFNγposNK-cells: 0.53 vs. 2.09%, P = 0.007). Responses to in-vitro HIV-infected autologous T cells were significantly lower in herpes simplex virus 2 (HSV-2)-infected women (P = 0.003). IFNγ NK cell responses to autologous HIV-infected cells were associated with lower risk of HIV acquisition (odds ratio adjusted for age, gel arm, HSV-2 and immune activation: 0.582, 95% confidence interval 0.347-0.977, P = 0.04). At the time of exposure to HIV, women with impaired NK cell IFNγ responses were more likely to acquire HIV infection. NK cells, as early responders to viral exposure, were associated with lower risk of HIV acquisition, independent of the intercalated effect of HSV-2 infection suppressing NK cell responses.

T cells become licensed in the lung to enter the central nervous system

The blood–brain barrier (BBB) and the environment of the central nervous system (CNS) guard the nervous tissue from peripheral immune cells. In the autoimmune disease multiple sclerosis, myelin-reactive T-cell blasts are thought to transgress the BBB and create a pro-inflammatory environment in the CNS, thereby making possible a second autoimmune attack that starts from the leptomeningeal vessels and progresses into the parenchyma. Using a Lewis rat model of experimental autoimmune encephalomyelitis, we show here that contrary to the expectations of this concept, T-cell blasts do not efficiently enter the CNS and are not required to prepare the BBB for immune-cell recruitment. Instead, intravenously transferred T-cell blasts gain the capacity to enter the CNS after residing transiently within the lung tissues. Inside the lung tissues, they move along and within the airways to bronchus-associated lymphoid tissues and lung-draining mediastinal lymph nodes before they enter the blood circulation from where they reach the CNS. Effector T cells transferred directly into the airways showed a similar migratory pattern and retained their full pathogenicity. On their way the T cells fundamentally reprogrammed their gene-expression profile, characterized by downregulation of their activation program and upregulation of cellular locomotion molecules together with chemokine and adhesion receptors. The adhesion receptors include ninjurin 1, which participates in T-cell intravascular crawling on cerebral blood vessels. We detected that the lung constitutes a niche not only for activated T cells but also for resting myelin-reactive memory T cells. After local stimulation in the lung, these cells strongly proliferate and, after assuming migratory properties, enter the CNS and induce paralytic disease. The lung could therefore contribute to the activation of potentially autoaggressive T cells and their transition to a migratory mode as a prerequisite to entering their target tissues and inducing autoimmune disease.

Effective T‐cell recall responses require the taurine transporter Taut

T-cell activation and the subsequent transformation of activated T cells into T-cell blasts require profound changes in cell volume. However, the impact of cell volume regulation for T-cell immunology has not been characterized. Here we studied the role of the cell-volume regulating osmolyte transporter Taut for T-cell activation in Taut-deficient mice. T-cell mediated recall responses were severely impaired in taut(-/-) mice as shown with B16 melanoma rejection and hapten-induced contact hypersensitivity. CD4(+) and CD8(+) T cells were unequivocally located within peripheral lymph nodes of unprimed taut(-/-) mice but significantly decreased in taut(-/-) compared with taut(+/+) mice following in vivo activation. Further analysis revealed that Taut is critical for rescuing T cells from activation-induced cell death in vitro and in vivo as shown with TCR, superantigen, and antigen-specific activation. Consequently, reduction of CD4(+) and CD8(+) T cells in taut(-/-) mice upon antigen challenge resulted in impaired in vivo generation of T-cell memory. These findings disclose for the first time that volume regulation in T cells is an element in the regulation of adaptive immune responses and that the osmolyte transporter Taut is crucial for T-cell survival and T-cell mediated immune reactions.

Activated T-cells and pro-inflammatory cytokines differentially regulate prostaglandin E2 secretion by mesenchymal stem cells

In recent years it has become clear that mesenchymal stem or stromal cells (MSCs) are capable of modulating inflammatory and immune responses through interaction with a wide variety of cells. Whereas several studies indicated that PGE2 is one of the chief soluble mediators involved in these processes, here we investigated prostaglandin E2 (PGE2) production of murine bone marrow- (BM-) and adipose tissue- (Ad-) derived MSCs stimulated with pro-inflammatory cytokines TNF-α and IFN-γ, or co-cultured with ConA-induced T-cell blasts. We found that both MSC populations are able to produce high amounts of PGE2 in MSC/activated T-cell co-cultures. This effect was markedly attenuated when direct cell–cell contact was prevented in transwell system, indicating that the elicitation of the PGE2 secretion of MSCs is contact-dependent in this experimental setting. In contrast, when soluble recombinant pro-inflammatory cytokines were added to the MSC cultures, TNF-α and IFN-γ act synergistically to induce PGE2 production, whereas only high amount of TNF-α but not IFN-γ was able to do so alone. Although the PGE2 secretion by MSCs was completely abrogated by addition of indomethacin under all culture conditions tested, L-NMA, a NOS inhibitor could only partially inhibit it when the cells were elicited in the concomitant presence of TNF-α and IFN-γ. These results, combined with others, suggest that NO acts downstream of IFN-γ but upstream of COX2. Taken together, our findings demonstrate that the induction of PGE2 secretion by BM- and Ad-MSCs is not mediated by a single or unique, nonredundant molecular mechanism under different experimental conditions.

A mosaic de novo duplication of 17q21–25 is associated with GH insensitivity, disturbed in vitro CD28-mediated signaling, and decreased STAT5B, PI3K, and NF-κB activation

The established causes of GH insensitivity include defects of the GH receptor and STAT5B. The latter condition is also characterized by severe immunodeficiency. A recent case with short stature, GH resistance, and immunodeficiency due to an IκB mutation suggests that the NF-κB pathway may interact with STAT5B signaling. Here, we present a case of a short child with several congenital anomalies as well as GH insensitivity and mild immunodeficiency associated with a mosaic de novo duplication of chromosome 17q21-25, suggesting that overexpression of one of the duplicated genes may be implicated in GH resistance. In vitro studies on blood lymphocytes showed disturbed signaling of the CD28 pathway, involving NF-κB and related proteins. Functional studies on cultured skin fibroblasts revealed that NF-κB activation, PI3K activity, and STAT5 phosphorylation in response to GH were suppressed, while the sensitivity to GH in terms of MAPK phosphorylation was increased. An in silico analysis of the duplicated genes showed that MAP3K3 and PRKCA are associated with the NF-κB pathway. Baseline MAP3K3 expression in T-cell blasts (TCBs) was normal, but PRKCA expression in TCBs and fibroblasts was significantly higher than that in control cells. We conclude that the 17q21-25 duplication is associated with GH insensitivity and disturbed STAT5B, PI3K, and NF-κB signaling, possibly due to PRKCA mRNA overexpression.