Milk Fat Globule Proteins Are Relevant Bovine Milk Allergens in Patients with α­Gal Syndrome.

Alpha-gal syndrome (AGS) is a mammalian meat allergy associated with tick bites and specific IgE to the oligosaccharide galactose-α-1,3-galactose (α-gal). Recent studies have shown that 10-20% of AGS patients also react to the dairy proteins. Considering the already described role of the meat lipid fraction in AGS manifestations, the aim of this work has been to investigate whether the milk fat globule proteins (MFGPs) could be involved in AGS. The MFGPs are extracted and their recognition by the IgE of AGS patients is proved through immunoblotting experiments. The identification of the immunoreactive proteins by LC-HRMS analysis allows to demonstrate for the first time that butyrophillin, lactadherin, and xanthine oxidase (XO) are α-gal glycosylated. The role of xanthine oxidase seems to be prevalent since it is highly recognized by both the anti-α-gal antibody and AGS patient sera. The results obtained in this study provide novel insights in the characterization of α-Gal carrying glycoproteins in bovine milk, supporting the possibility that milk, especially in its whole form, may give reactions in AGS patients. Although additional factors are probably associated with the clinical manifestations, the avoidance of milk and milk products should be considered in individuals with AGS showing symptoms related to milk consumption.

Comparing T Cell Subsets in Broncho-Alveolar Lavage (BAL) and Peripheral Blood in Patients with Advanced Lung Cancer.

BACKGROUND: Lung cancer (LC) tissue for immunological characterization is often scarce. We explored and compared T cell characteristics between broncho-alveolar lavage from tumor affected (t-BAL) and contralateral lung (cl-BAL), with matched peripheral blood (PB). METHODS: BAL and PB were collected during bronchoscopy for diagnostic and/or therapeutic purposes in patients with monolateral primary lesion. RESULTS: Of 33 patients undergoing BAL and PB sampling, 21 had histologically-confirmed LC. Most cases were locally-advanced or metastatic non-small cell LC. T cell characteristics were not significantly different in t-BAL vs. cl-BAL. Compared to PB, CD8 T cells in BAL presented features of immune activation and exhaustion (high PD-1, low IFN-g production). Accordingly, regulatory CD4 T cells were also higher in BAL vs. PB. When dichotomizing T cell density in t-BAL in high and low, we found that PD-L1 expression in LC was associated with T cell density in t-BAL. T-BAL with high T cell density had higher %IFN-g+CD8 T cells and lower %T-regs. CONCLUSION: In BAL from advanced LC patients, T cells present features of exhaustion. T cells in t-BAL could be the best surrogate of tumor-infiltrating T cell, and future studies should evaluate T cell phenotype and density as potential biomarkers for cancer immunotherapy outcome.

Immunonutrition in ovarian cancer: clinical and immunological impact?

OBJECTIVE: Malnutrition is frequent in ovarian cancer (OC) patients and may compromise post-operative outcomes. The aim of this study is to evaluate the impact of pre-operative immunonutrition on the surgical outcome of OC patients, and on their nutritional, inflammatory and peripheral blood immune status. METHODS: A prospective study was performed between September 2016 and April 2020. Immune-enhancing enteral nutrition was administered to 42 patients before surgery according to their nutritional status assessed by the Malnutritional Universal Screening Tool. Biochemical and hematological monitoring was performed before and after immunonutrition. Post-operative outcomes were assessed and compared with those of a similar group of patients treated without nutritional support. RESULTS: Of the 42 immune-nourished patients, 23 (54.8%) had a low, 11 (26.2%) an intermediate and 8 (19%) a high risk of malnutrition. After the immunonutritional intake, significant variations of prealbumin, creatinine and white blood cells were detected. All T cell populations had an increasing trend, in particular CD3+ T lymphocytes (p=0.020), CD3+CD8+ cytotoxic T lymphocytes (p=0.046) and lymphocyte with HLA-DR expression (p=0.012). The rate of grade II-III post-operative complications was lower (21.4% vs. 42.9%, p=0.035) and the time of hospitalization was shorter (7.5 vs. 9.2, p=0.009) in the immune-nourished group. CONCLUSION: Pre-operative immunonutrition improves the surgical outcome of OC patients. After immunonutrition, an increase of CD3+CD8+ cytotoxic T lymphocytes was observed.

Dihydroorotate dehydrogenase inhibition reveals metabolic vulnerability in chronic myeloid leukemia.

The development of different generations of BCR-ABL1 tyrosine kinase inhibitors (TKIs) has led to the high overall survival of chronic myeloid leukemia (CML) patients. However, there are CML patients who show resistance to TKI therapy and are prone to progress to more advanced phases of the disease. So, implementing an alternative approach for targeting TKIs insensitive cells would be of the essence. Dihydroorotate dehydrogenase (DHODH) is an enzyme in the de novo pyrimidine biosynthesis pathway that is located in the inner membrane of mitochondria. Here, we found that CML cells are vulnerable to DHODH inhibition mediated by Meds433, a new and potent DHODH inhibitor recently developed by our group. Meds433 significantly activates the apoptotic pathway and leads to the reduction of amino acids and induction of huge metabolic stress in CML CD34+ cells. Altogether, our study shows that DHODH inhibition is a promising approach for targeting CML stem/progenitor cells and may help more patients discontinue the therapy.

Novel Insights in Anti-CD38 Therapy Based on CD38-Receptor Expression and Function: The Multiple Myeloma Model.

Multiple myeloma (MM) is a hematological disease characterized by the proliferation and accumulation of malignant plasmacells (PCs) in the bone marrow (BM). Despite widespread use of high-dose chemotherapy in combination with autologous stem cell transplantation (ASCT) and the introduction of novel agents (immunomodulatory drugs, IMiDs, and proteasome inhibitors, PIs), the prognosis of MM patients is still poor. CD38 is a multifunctional cell-surface glycoprotein with receptor and ectoenzymatic activities. The very high and homogeneous expression of CD38 on myeloma PCs makes it an attractive target for novel therapeutic strategies. Several anti-CD38 monoclonal antibodies have been, or are being, developed for the treatment of MM, including daratumumab and isatuximab. Here we provide an in-depth look atCD38 biology, the role of CD38 in MM progression and its complex interactions with the BM microenvironment, the importance of anti-CD38 monoclonal antibodies, and the main mechanisms of antibody resistance. We then review a number of multiparametric flow cytometry techniques exploiting CD38 antigen expression on PCs to diagnose and monitor the response to treatment in MM patients.

A Clinically Applicable Approach to the Classification of B-Cell Non-Hodgkin Lymphomas with Flow Cytometry and Machine Learning.

The immunophenotype is a key element to classify B-cell Non-Hodgkin Lymphomas (B-NHL); while it is routinely obtained through immunohistochemistry, the use of flow cytometry (FC) could bear several advantages. However, few FC laboratories can rely on a long-standing practical experience, and the literature in support is still limited; as a result, the use of FC is generally restricted to the analysis of lymphomas with bone marrow or peripheral blood involvement. In this work, we applied machine learning to our database of 1465 B-NHL samples from different sources, building four artificial predictive systems which could classify B-NHL in up to nine of the most common clinico-pathological entities. Our best model shows an overall accuracy of 92.68%, a mean sensitivity of 88.54% and a mean specificity of 98.77%. Beyond the clinical applicability, our models demonstrate (i) the strong discriminatory power of MIB1 and Bcl2, whose integration in the predictive model significantly increased the performance of the algorithm; (ii) the potential usefulness of some non-canonical markers in categorizing B-NHL; and (iii) that FC markers should not be described as strictly positive or negative according to fixed thresholds, but they rather correlate with different B-NHL depending on their level of expression.

Features, reason for testing, and changes with time of 583 paroxysmal nocturnal hemoglobinuria clones from 529 patients: a multicenter Italian study.

In this study, we aimed at disclosing the main features of paroxysmal nocturnal hemoglobinuria (PNH) clones, their association with presentation syndromes, and their changes during follow-up. A large-scale, cooperative collection (583 clones from 529 patients) of flow cytometric and clinical data was entered into a national repository. Reason for testing guidelines were provided to the 41 participating laboratories, which followed the 2010 technical recommendations for PNH testing by Borowitz. Subsequently, the 30 second-level laboratories adopted the 2012 guidelines for high-resolution PNH testing, both upon order by the local clinicians and as an independent laboratory initiative in selected cases. Type3 and Type2 PNH clones (total and partial absence of glycosyl-phosphatidyl-inositol-anchor, respectively) were simultaneously present in 54 patients. In these patients, Type3 component was sevenfold larger than Type2 (p < 0.001). Frequency distribution analysis of solitary Type3 clone size (N = 442) evidenced two discrete patterns: small (20% of peripheral neutrophils) and large (> 70%) clones. The first pattern was significantly associated with bone marrow failure and myelodysplastic syndromes, the second one with hemolysis, hemoglobinuria, and thrombosis. Pediatric patients (N = 34) showed significant preponderance of small clones and bone marrow failure. The majority of PNH clones involved neutrophils, monocytes, and erythrocytes. Nevertheless, we found clones made exclusively by white cells (N = 13) or erythrocytes (N = 3). Rare cases showed clonal white cells restricted only to monocytes (6 cases) or neutrophils (3 cases). Retesting over 1-year follow-up in 151 cases showed a marked clone size increase in 4 cases and a decrease in 13, demonstrating that early breaking-down of PNH clones is not a rare event (8.6% of cases). This collaborative nationwide study demonstrates a clear-cut difference in size between Type2 and Type3 clones, emphasizes the existence of just two classes of PNH presentations based on Type3 clone size, depicts an asymmetric cellular composition of PNH clones, and documents the possible occurrence of changes in clone size during the follow-up.

Survivin-peptide vaccination elicits immune response after allogeneic nonmyeloablative transplantation: a safe strategy to enhance the graft versus tumor effect.

Allogeneic hematopoietic cell transplantation (allo-HCT) is an adoptive immunotherapy strategy whose effectiveness relies on graft-versus-tumor (GVT) effect. We explored the feasibility of enhancing GVT after allo-HCT by peptide vaccination. Two myeloma patients were transplanted with a fludarabine-total body irradiation conditioning regimen and vaccinated with an HLA-A*0201-restricted modified survivin nonapeptide, plus montanide as adjuvant. At time of first vaccination, one patient had just attained serological remission despite documented relapse after transplant, while the other patient was in stable disease. Both patients had an immune response to vaccination: the frequency of survivin-specific CD8+ T cells increased between second and sixth vaccination and accounted for 0.5-0.8% of CD8+ cells; CD8+ cells were functional in ELISPOT assay. The first patient persists in complete remission with a follow-up of >5 years, while the second patient did not have a clinical response and vaccination was halted. We analyzed the T-cell receptor (TCR) repertoire of the first patient by spectratyping and found that vaccination did not affect the diversity of TCR profile, indicating that survivin clonotypes were probably spread in multiple TCR families. We generated a limited number (n = 4) of survivin-specific T cell clones: three were reactive only against the modified peptide, whereas one clone recognized also the naive peptide. Peptide vaccination is safe and applicable after allo-HCT and elicits an efficient antigen-specific T cell response without causing graft-versus-host disease.

Multicenter validation of a simplified method for paroxysmal nocturnal hemoglobinuria screening.

BACKGROUND: Paroxysmal nocturnal hemoglobinuria (PNH) diagnostic guidelines recommend single-tube five- to six-color or two-tube four-color assays. PNH clones are detectable in only a fraction of patients at risk, and screening for new PNH cases can be complex and expensive. In this multicenter study, we have validated a simplified, one-tube two-color FLAER-based assay suitable for PNH screening. METHODS: Six laboratories received samples containing spiked PNH leukocyte clones to be analyzed in parallel with a common six-color cocktail (FLAER/CD24/CD45/CD64/CD15/CD14) and a simplified two-color mixture (FLAER/CD15), a shared calibration procedure, and a common analysis protocol. Replicate precision and sensitivity tests were performed on PNH patients, from undiluted to 1:10 000. Specificity tests were performed on normal donors to identify the possible sources of artifacts. RESULTS: The performance comparison between six-color and two-color assays showed an excellent agreement for granulocyte PNH clones. Dilution experiments showed an accurate detectability down to 0.01% sensitivity level for granulocyte PNH clones and to 1% for monocytes. Specificity experiments disclosed that basophils and platelets can contaminate the monocyte gate and generate false PNH events. CONCLUSIONS: A simplified two-color (FLAER/CD15) PNH screening test has been validated in a highly standardized multicenter study and proved feasible and effective in ongoing regional programs. Precision, sensitivity, and specificity of the simplified test for granulocytes were comparable to the more complex and expensive six-color assay and applicable for screening also in peripheral laboratories. The diagnostic confirmation of PNH should be always performed by a reference center using the established technique on all cell lineages.

Cytokine-induced killer cells engineered with exogenous T-cell receptors directed against melanoma antigens: enhanced efficacy of effector cells endowed with a double mechanism of tumor recognition.

Cytokine-induced killer (CIK) cells consist of a heterogeneous population of polyclonal T lymphocytes displaying NK phenotype and HLA-unrestricted cytotoxic activity against a broad range of tumors. We sought to determine whether transduction of CIK cells with T cell receptor (TCR) genes specific for tumor-associated antigens could generate effector cells endowed with a double mechanism of tumor recognition. HLA-A2-restricted TCR-transduced (TD) CIK directed against the melanoma antigens Mart1 and NY-ESO1 were generated by lentiviral transduction and successfully expanded over a 3-4-week period. TD-CIK cells were both CD3(+)/CD56(-) and CD3(+)/CD56(+) (31±8% and 59±9%, respectively), indicating that both major histocompatibility complex (MHC)-restricted T cells and MHC-unrestricted CIK could be targeted by lentiviral transduction. At the end of the culture, the majority of both unmodified and TD-CIK displayed an effector memory phenotype, without considerable expression of replicative senescence and exhaustion markers. Functionally, TD-CIK specifically recognized tumor cells expressing the relevant antigen as well as maintained their MHC-unrestricted tumor activity. The cytotoxic activity of TD-CIK against HLA-A2(+) melanoma cell lines was significantly higher than the untransduced counterparts at a low effector:target ratio (cytotoxic activity of TD-CIK was from 1.9- to 4.3-fold higher than untransduced counterparts). TD-CIK were highly proficient in releasing high amount of IFN-γ upon antigen-specific stimulation and were able to recognize primary melanoma targets. In conclusion, we showed that (1) the reproducibility and simplicity of CIK transduction and expansion might solve the problem of obtaining adequate numbers of potent antitumor effector cells for adoptive immunotherapy; (2) the presence of both terminal effectors as well as of less differentiated progenitors might confer them long survival in vivo; and (3) the addition of an MHC-restricted antigen recognition allows not only targeting tumor surface antigens but also a wider range of cytoplasmic or nuclear antigens, involved in tumor proliferation and survival. TD-CIK cells with a double mechanism of tumor recognition are an attractive and alternative tool for the development of efficient cell therapeutic strategies.

Hypersensitivity reaction to human papillomavirus vaccine due to polysorbate 80.

A 17-year-old girl reported generalised urticaria, eyelid angioedema, rhino-conjunctivitis, dyspnoea and wheezing 1 h after third intramuscular administration of quadrivalent human papilloma virus vaccine (Gardasil). She was treated with antihistamine, and corticosteroids with prompt relief of rhinitis and dyspnoea, while urticaria and angioedema lasted 24 h. Intradermal test with Gardasil, which contains polysorbate 80 (PS80), resulted positive, while skin tests with the bivalent vaccine were negative. Prick test performed with PS80 resulted positive in the patient and negative in ten healthy controls. The CD203 basophil activation test result was negative for PS80 at all the tested dilutions and specific IgE was not found. As flu vaccine was recommended, the authors skin tested two flu vaccine, one containing PS80 (Fluarix, GSK), which resulted positive and another flu vaccine with no adjuvant or preservative (Vaxigrip, Sanofi Pasteur MSD), which gave negative results. The patient then received Vaxigrip without adverse reactions.

Cells lacking the fumarase tumor suppressor are protected from apoptosis through a hypoxia-inducible factor-independent, AMPK-dependent mechanism.

Loss-of-function mutations of the tumor suppressor gene encoding fumarase (FH) occur in individuals with hereditary leiomyomatosis and renal cell cancer syndrome (HLRCC). We found that loss of FH activity conferred protection from apoptosis in normal human renal cells and fibroblasts. In FH-defective cells, both hypoxia-inducible factor 1α (HIF-1α) and HIF-2α accumulated, but they were not required for apoptosis protection. Conversely, AMP-activated protein kinase (AMPK) was activated and required, as evidenced by the finding that FH inactivation failed to protect AMPK-null mouse embryo fibroblasts (MEFs) and AMPK-depleted human renal cells. Activated AMPK was detected in renal cysts, which occur in mice with kidney-targeted deletion of Fh1 and in kidney cancers of HLRCC patients. In Fh1-null MEFs, AMPK activation was sustained by fumarate accumulation and not by defective energy metabolism. Addition of fumarate and succinate to kidney cells led to extracellular signal-regulated kinase 1/2 (ERK1/2) and AMPK activation, probably through a receptor-mediated mechanism. These findings reveal a new mechanism of tumorigenesis due to FH loss and an unexpected pro-oncogenic role for AMPK that is important in considering AMPK reactivation as a therapeutic strategy against cancer.

Ex vivo-expanded bone marrow CD34(+) for acute myocardial infarction treatment: in vitro and in vivo studies.

BACKGROUND AIMS: Bone marrow (BM)-derived cells appear to be a promising therapeutic source for the treatment of acute myocardial infarction (AMI). However, the quantity and quality of the cells to be used, along with the appropriate time of administration, still need to be defined. We thus investigated the use of BM CD34(+)-derived cells as cells suitable for a cell therapy protocol (CTP) in the treatment of experimental AMI. METHODS: The need for a large number of cells was satisfied by the use of a previously established protocol allowing the expansion of human CD34(+) cells isolated from neonatal and adult hematopoietic tissues. We evaluated gene expression, endothelial differentiation potential and cytokine release by BM-derived cells during in vitro culture. Basal and expanded CD34(+) cells were used as a delivery product in a murine AMI model consisting of a coronary artery ligation (CAL). Cardiac function recovery was evaluated after injecting basal or expanded cells. RESULTS: Gene expression analysis of in vitro-expanded cells revealed that endothelial markers were up-regulated during culture. Moreover, expanded cells generated a CD14(+) subpopulation able to differentiate efficiently into VE-cadherin-expressing cells. In vivo, we observed a cardiac function recovery in mice sequentially treated with basal and expanded cells injected 4 h and 7 days after CAL, respectively. CONCLUSIONS: Our data suggest that combining basal and expanded BM-derived CD34(+) cells in a specific temporal pattern of administration might represent a promising strategy for a successful cell-based therapy.

Prognostic relevance of cytometric quantitative assessment in patients with myelodysplastic syndromes.

OBJECTIVES: Morphology and cytogenetics are currently used to define prognosis in myelodysplastic syndromes (MDS). However, these parameters have some limits. Flow cytometry has been recently included in the diagnostic panel for MDS, and its prognostic significance is under evaluation. METHODS: Marrow aspirates from 424 MDS patients were analyzed by flow cytometry to evaluate the impact of bone marrow cell immunophenotype on overall survival (OS) and leukemia-free survival (LFS). The immature compartment of myeloblasts was analyzed by the quantitative expression of CD34 (<3% vs. ≥3%), CD117, and CD11b(-) /CD66b(-) (<5% vs. ≥5%); myeloid maturation was analyzed by the expression of CD11b(+) /CD66b(++) (<15% vs. ≥15%) and CD11b(+) /CD66b(+) (<25% vs. ≥25%). RESULTS: In univariate analysis, the expression of immaturity markers (CD34(+) , CD117(+) , and CD11b(-) /CD66b(-) ) was associated with shorter LFS and OS (P < 0.0001); higher expression of differentiation markers (CD11b(+) /CD66b(++) and CD11b(+) /CD66b(+) ) was associated with longer LFS (P < 0.0001 and P = 0.0002, respectively) and OS (P < 0.0001). In multivariate analysis, expression of CD34(+) (P = 0.007), CD117(+) (P = 0.013), and CD11b(+) /CD66b(++) (P = 0.023) retained independent prognostic value for OS, while only the expression of CD34(+) was a prognostic factor for LFS (P = 0.0003). Two different risk groups were defined according to the presence of 0-1 or ≥2 of these factors with significant different LFS and OS (P < 0.0001). This score showed prognostic value in predicting survival even in subanalysis according to IPSS and WHO subgroups. CONCLUSIONS: Flow cytometric analysis in MDS may provide meaningful prognostic information. Blast percentage expressed as CD117(+) or CD34(+) cells and the quantitative assessment of myeloid maturation showed prognostic value for survival.

Cluster analysis of immunophenotypic data: the example of chronic lymphocytic leukemia.

Studies of gene expression profiling have been successfully used for the identification of molecules to be employed as potential prognosticators. In analogy with gene expression profiling, we have previously proposed an original method to identify the immunophenotypic signature of chronic lymphocytic leukemia (CLL) subsets with different prognosis, named surface-antigen expression profiling. According to this method, expression data for surface markers can be successfully analyzed by data mining tools identical to those employed in gene expression profiling studies, including unsupervised and supervised algorithms, with the aim to identify the immunophenotypic signature of CLL subsets with different prognosis. By employing an identical approach for investigating the reactivity of a wide panel of monoclonal antibodies provided by the "Ninth International Workshop on Leukocyte Differentiation Antigens", we were able to identify some of them (i.e. TCL1, CCR7, FCRL2, FCRL3, and CD150) as additional potential markers with prognostic relevance in CLL. These suggestions need to be confirmed: (i) in a new set of clinically characterized CLL cases; (ii) in combination with other prognostic markers in the context of comprehensive scoring systems for clinical outcome prediction.

Deregulation of the PI3K and KRAS signaling pathways in human cancer cells determines their response to everolimus.

Personalized cancer medicine is based on the concept that targeted therapies are effective on subsets of patients whose tumors carry specific molecular alterations. Several mammalian target of rapamycin (mTOR) inhibitors are in preclinical or clinical trials for cancers, but the molecular basis of sensitivity or resistance to these inhibitors among patients is largely unknown. Here we have identified oncogenic variants of phosphoinositide-3-kinase, catalytic, alpha polypeptide (PIK3CA) and KRAS as determinants of response to the mTOR inhibitor everolimus. Human cancer cells carrying alterations in the PI3K pathway were responsive to everolimus, both in vitro and in vivo, except when KRAS mutations occurred concomitantly or were exogenously introduced. In human cancer cells with mutations in both PIK3CA and KRAS, genetic ablation of mutant KRAS reinstated response to the drug. Consistent with these data, PIK3CA mutant cells, but not KRAS mutant cells, displayed everolimus-sensitive translation. Importantly, in a cohort of metastatic cancer patients, the presence of oncogenic KRAS mutations was associated with lack of benefit after everolimus therapy. Thus, our results demonstrate that alterations in the KRAS and PIK3CA genes may represent biomarkers to optimize treatment of patients with mTOR inhibitors.

IL-18 paradox in pancreatic carcinoma: elevated serum levels of free IL-18 are correlated with poor survival.

The role of the proinflammatory interleukin (IL)-18 in cancer progression remains controversial; we thus examined the hypothesis that impaired antitumor immune response in pancreatic carcinoma patients is related to elevated levels of its natural inhibitor IL-18 binding protein (BP) and/or to alteration in the IL-18 receptor complex expression and function. IL-18 and IL-18 binding protein isoform a (BPa) was assessed in pancreatic carcinoma patients at various disease stages, and after surgery/chemotherapy; free bioactive IL-18 concentrations were calculated. IL-18 receptor complex expression in lymphocyte subsets was analyzed and signaling function was assessed versus healthy donors. Carcinoma cells exhibited below normal IL-18BPa expression and above normal IL-18 expression. Circulating IL-18BPa and IL-18 were above controls. Unexpectedly, free unbound IL-18 serum levels were correlated with disease severity and poor survival. IL-18BPa levels were unchanged by surgery but free IL-18 levels were elevated. Gemcitabine with 5-fluorouracil or oxaliplatin, but not alone, increased IL-18 and free IL-18 levels statistically significantly, without affecting IL-18BPa. Spontaneous/induced IL-18 receptor alpha and receptor beta expression in peripheral blood lymphocyte subsets from patients with advanced disease were near-normal, although CD4+ and CD8+ cells were fewer in percentage, and fully functional in inducing interferon-gamma. IL-18 is proposed as novel adjuvant cancer therapy, but free IL-18 levels are increased in the blood of pancreatic carcinoma patients, despite elevated IL-18BP levels, and are associated with poor survival; this highlights recent experimental insights into the prometastatic and proangiogenic effects of IL-18, and suggests that careful preclinical studies are needed to determine the proper application of IL-18 in cancer therapy.

T cell receptor (TCR) gene transfer with lentiviral vectors allows efficient redirection of tumor specificity in naive and memory T cells without prior stimulation of endogenous TCR.

We investigated the possibility of introducing exogenous T cell receptor (TCR) genes into T cells by lentiviral transduction, without prior stimulation of endogenous TCR with anti-CD3. TCR transfer is used to impose tumor antigen specificity on recipient T cells, but sustained activation required for retroviral transduction may affect the clinical efficacy of engineered T cells. Cytokine stimulation makes T cells susceptible to lentiviral transduction in the absence of TCR triggering, but this advantage has never been exploited for TCR transfer. Autoimmune diseases are a source of high-affinity TCRs specific for self/tumor antigens. We selected, from a patient with vitiligo, a Mart1-specific TCR based on intrinsic interchain pairing properties and functional avidity. After lentiviral transduction of human peripheral blood mononuclear cells, preferential pairing of exogenous alpha and beta chains was observed, together with effective recognition of Mart1(+) melanoma cells. We tested transduction efficiency on various T cell subsets prestimulated with interleukin (IL)-2, IL-7, IL-15, and IL-21 (alone or in combination). Both naive and unfractionated CD8(+) T cells could be transduced without requiring endogenous TCR triggering. IL-7 plus IL-15 was the most powerful combination, allowing high levels of transgene expression without inducing T cell differentiation (34 +/- 5% Mart1-TCR(+) cells in naive CD8(+) and 16 +/- 6% in unfractionated CD8(+)). Cytokine-prestimulated, Mart1-redirected naive and unfractionated CD8(+) cells expanded better than CD3-CD28-prestimulated counterparts in response to both peptide-pulsed antigen-presenting cells and Mart1(+) melanoma cells. This strategy allows the generation of tumor-specific T cells encompassing truly naive T cells, endowed with an intact proliferative potential and a preserved differentiation stage.

Microenvironment drives the endothelial or neural fate of differentiating embryonic stem cells coexpressing neuropilin-1 and Flk-1.

The observation that the architecture of the cardiovascular and nervous systems is drawn by common guidance cues and the closeness between neural progenitors and endothelial cells in the vascular niche strongly suggests the existence of links between endothelial and neural cell fates. We identified an embryonic stem cell-derived discrete, nonclonal cell population expressing the two vascular endothelial growth factor receptors neuropilin-1 (Nrp1) and Flk1 that differentiates in vitro toward endothelial or neural phenotypes depending on microenvironmental cues. When microinjected in the chick embryo, Nrp1(+) cells integrate within the host, developing vessels and brain, and acquire endothelial and neural markers, respectively. These results show that precursors of endothelial cells and precursors of neural cells arise from the same pool of differentiating embryonic stem cells and share the expression of Nrp1 and Flk1. These data reinforce the parallelism between vascular and nervous system at the level of cell fate and commitment and open new perspective in regenerative medicine of neurovascular diseases.