Expansion of dendritic cells derived from human CD34+ cells in static and continuous perfusion cultures

We examined the effects of different cytokine combinations and culture conditions on the expansion and modulation of cell surface antigens of CD34⁺ derived dendritic cells (DCs), the most efficient antigen-presenting cells capable of stimulating resting T cells in the primary immune response. Cells with a dendritic morphology and expressing HLA-DR, CD1a, S100 and CD83 were maximally expanded under serum-free conditions with the addition of SCF, GM-CSF, TNF-α, TGF-β and Flt-3 ligand (fold increase of CD1a⁺ cells = 102 ± 32 after 2 weeks of culture). CD34⁺ cells were also grown under continuous flow conditions in an artificial capillary system; after 14 d of culture, the expansion in the total cell number was lower than that of the static cultures (3.3 ± 2 v 18.9 ± 4) but the percentage of CD1a⁺/CD83⁺/CD80⁺ cells was considerably higher, whereas the CD14⁺ cells were significantly reduced (8.9 ± 2 v 26 ± 13). In continuous perfusion cultures, low levels of DC precursors and of LTC-IC were still present up to day 14. The DCs generated under flow conditions stimulated the mixed leucocyte reaction (MLR) more than the cells grown in static cultures. By electron microscopy, cells grown in the continuous flow system showed an increased number of large cells with numerous dendritic processes and abundant multilamellar complexes. The cells expanded under these conditions were sorted on the basis of their light-scatter properties into two fractions: one containing a predominance of CD1a⁺/S100⁺/CD83⁺/CD80⁺/CD14^?‘large cells’ with great internal complexity (mature DCs); the second including ‘small cells’ either CD33⁺/CD14⁺, CD33⁺/CD15⁺ or CD33⁺/CD13^±/CD14^?. The DCs generated and selected with this method are therefore particularly well suited for immunotherapeutic protocols.     

Large-cell variants of mantle cell lymphoma: cytologic characteristics and p53 anomalies may predict poor outcome

Large-cell variants are uncommon in mantle cell lymphoma (MCL). Here we describe the pathologic and clinical findings in five patients with large-cell lymphoma related to MCL (L-MCL), and compare them to a group of classic small-cell MCL (s-MCL) cases. Histologically, the MC origin of the large cells was evinced by their association with a small mantle cell component in the same tissue, or their distribution in a classic mantle zone pattern, or their development in a patient with previous s-MCL. The large cells were either pleomorphic mantle cells (case 1) or transformed blast-like cells (cases 2–5). The median nuclear diameter, median nuclear area and proliferation index of L-MCLs and s-MCLs, were statistically different. Immunophenotypic characterization of four specimens of L-MCL and 10 of s-MCLs with a large panel of antibodies showed the classic findings of MCL, i.e. the IgM⁺ D^+/?, CD5⁺, CD10^?, CD23^? phenotype in all cases except two (one CD5^? and one CD23⁺), and the association with a loose follicular dendritic cell network. Two of four L-MCLs and 5/10 s-MCLs demonstrated rearrangements of the bcl-1 gene by Southern blot or by polymerase chain reaction (PCR); 2/4 L-MCLs and 1/9 s-MCLs had p53 mutations on single-strand conformation polymorphism analysis; none of the 14 specimens showed rearrangement of bcl-2 by PCR or bcl-6 and c-myc by Southern blot. All patients with ‘transformed’ histology (versus 37% of all others) died of lymphoma; their survival (15–18 months; median 17) was much shorter than that of all the others (28–117+ months; median 43) (P = 0.0035). All three patients with p53 anomalies, two of whom had tumours with transformed histology, died of their disease in a short time (15, 18 and 28 months). In contrast, the presence of bcl-1 rearrangements did not have prognostic implications. This study documents the existence of large-cell variants of MCL and the poor prognosis associated with the ‘transformed’ cytologic type and/or p53 abnormalities.     

Immunoadsorption of Immunoglobulins Alters Intracytoplasmic Type 1 and Type 2 T Cell Cytokine Production in Patients with Refractory Autoimmune Diseases

Abstract: Intracellular cytokine staining and flow cytometry were used to investigate whether immunoadsorption (IA) of immunoglobulins alters intracytoplasmic cytokine production in CD4⁺ and CD8⁺ T cells from the blood of patients with refractory rheumatoid arthritis (n = 7), membrane proliferative glomerulonephritis (n = 1), and Goodpasture's syndrome (n = 1). Four patients (Group 1) showed severely depressed production of TNF‐α, IL‐2, IFN‐γ, and IL‐4 by CD4⁺ and CD8⁺ T cells and responded to 3 IA sessions with significant increases in CD4⁺TNF‐α⁺, CD4⁺IL‐2⁺, and CD8⁺IL‐2⁺ T cells. Also, a tendency toward increased percentage levels of CD4⁺ T cells producing IFN‐γ or IL‐4 and of CD8⁺ T cells producing either TNF‐α or IFN‐γ was seen, but due to the small number of patients investigated, these differences did not attain statistic significance. Group 2 (n = 5) showed unimpaired intracellular cytokine levels and responded to IA with a heterogeneous pattern of changes in TNF‐α, IL‐2, IFN‐γ, and IL‐4 production, but these alterations were smaller than those in Group 1. The present findings indicate that the extracorporeal removal of immunoglobulins by anti‐IgG or protein A adsorber columns has an impact on T cell immunity and suggest that modulating effects on cellular immune system function are involved in the mode of action of IA.     

Mobilizing peripheral blood stem cells with high-dose G-CSF alone is as effective as with Dexa-BEAM plus G-CSF in lymphoma patients

We compared retrospectively the efficacy of granulocyte colony stimulating factor (G-CSF) alone with chemotherapy plus G-CSF in mobilizing CD34-positive cells in patients with malignant lymphoma. 35 patients underwent peripheral blood stem cell (PBSC) collection following mobilization either with 24 μg/kg G-CSF for 4 consecutive days (n = 18) or Dexa-BEAM chemotherapy plus 5 μg/kg G-CSF (n = 17). High-dose G-CSF was well tolerated with only slight bone pain and/or myalgia. The Dexa-BEAM therapy required hospitalization with a median duration of 21 d. The median number of apheresis procedures in both groups was two (range two to four), resulting in a median of 5.3 and 5.1 × 10⁶ CD34⁺ cells/kg. No patients in the G-CSF group, but one in the Dexa-BEAM group, failed to reach the target of collecting >2.0 × 10⁶ CD34⁺ cells/kg. The number of CFU-GM (10.4 v 6.0 × 10⁵/kg) and of BFU-E (10.6 v 4.5 × 10⁵/kg; P = 0.04) was higher in the G-CSF group than in the Dexa-BEAM group. A subset analysis of CD34⁺ cells was performed in 16 patients showing a higher mean of Thy-1 (CD90w) coexpression in the G-CSF than in the Dexa-BEAM group (4.8 v 1.8%, P = 0.12). Additionally the percentage of CD34⁺/CD38^? cells was higher in the G-CSF group (10.6% v 8.8%). However, these differences were not stastistically significant. The median time to leucocyte and platelet engraftment after high-dose chemotherapy was slightly shorter in the G-CSF than in the Dexa-BEAM group (9 v 10 and 12 v 13.5 d, respectively). These results demonstrate that high-dose G-CSF is as effective as Dexa-BEAM plus G-CSF in mobilizing peripheral blood stem cells and produces prompt engraftment. The major advantages of G-CSF mobilization were the safe outpatient self-application and the fixed-day apheresis.     

Acquisition of t(11;14) in a patient with chronic lymphocytic leukemia carrying both t(14;19)(q32;q13.1) and +12

A rare recurrent chromosomal translocation, t(14;19)(q32;q13), has been identified in a variety of B‐cell malignancies, including chronic lymphocytic leukemia (CLL). We report a unique case of CLL in a patient carrying both trisomy 12 and t(14;19) (q32;q13.1), in whom t(11;14)(q13;q32) developed at relapse. The patient was a 77‐yr‐old woman, and her lymphoma cells at presentation showed CD5⁺, CD10^?, CD19⁺, CD20⁺(dim), CD23⁺, CD38⁺, and CD11c⁺. At relapse, the patient's lymphoma cells showed positive staining for cyclin D1 in addition to CD5, CD20, and CD23. Lymphoma cells in specimens at both presentation and relapse were positive for lymphoid enhancer factor 1 (LEF1) and negative for sex‐determining region Y‐box 11 (SOX11). IGH‐BCL1 FISH became positive at relapse. Split FISH assay using BCL1, BCL3, IGH, and CCND1 probes on lymph node specimens obtained at presentation and at autopsy confirmed that the translocation of BCL3 was solely detected in the lymph node at presentation and detected BCL3 and CCND1 translocations in the specimen at autopsy. These observations indicated that IGH‐BCL3 and IGH‐CCND1 had occurred in the same clone after treatment of the disease. In line with immunohistochemical and cytogenetic studies, additional PCR analysis of the FR3‐JH region showed the same sequence derived from IGHV4‐34 in specimens obtained at disease onset and relapse.     

Functional,phenotypic and molecular characterization of cytokine low-responding circulating CD34+ haemopoietic progenitors

Circulating CD34⁺ cell populations characterized by a low rate (up to five) or high rate (more than five) of cell divisions were isolated from 8 d cultures in the presence of stem cell factor (SCF), interleukin-3 (IL-3), granulocyte-macrophage colony stimulating factor (GM-CSF), granulocyte colony stimulating factor (G-CSF), erythropoietin (EPO), Flt3 ligand and Peg-rHu megakaryocyte growth and development factor (Peg-rHuMGDF) using the fluorescent dye 5,6-carboxyfluorescein diacetate succinimidyl ester (CFDA-SE) and flow cytometric cell sorting. Phenotypic characterization of cells which had experienced up to five divisions (CFDA-SE^bright) showed a similar surface antigen expression to starting, freshly isolated CD34⁺ cells. Conversely, cells which experienced more than five divisions (CFDA-SE^dim) showed a differentiating behaviour, down-regulating CD34 antigen and acquiring differentiation markers. CFDA-SE^bright cells were significantly enriched in CD105 (endoglin) positive precursors as compared to both freshly isolated CD34⁺ and CFDA-SE^dim cells. Functional analysis indicated that CFDA-SE^bright had a 3-fold and 10-fold greater cumulative cloning efficiency as compared to freshly isolated CD34⁺ cells and CFDA-SE^dim cells, respectively. CFDA-SE^bright cells retained the vast majority of LTC-IC and showed a LTC-IC frequency 2.8-fold higher than that found in freshly isolated CD34⁺ cells. RT-PCR and Western blot analyses showed significantly higher bcl-2 RNA and protein levels in CFDA-SE^bright cells as compared to freshly isolated CD34⁺ and CFDA-SE^dim cells. This study indicates that cytokine low-responding circulating CD34⁺ cells (CFDA-SE^bright cells) represent a functionally, phenotypically and molecularly distinct multipotent progenitor population with biological properties associated with primitive precursors.     

Oxidative DNA damage in CD34+ myelodysplastic cells is associated with intracellular redox changes and elevated plasma tumour necrosis factor-α concentration

Ineffective haemopoiesis in the myelodysplastic syndromes (MDS) is mediated, at least in part, by apoptosis, though the mechanisms of apoptotic induction are unclear. Tumour necrosis factor-α (TNF-α) promotes apoptosis via intracellular oxygen free radical production, oxidation of DNA and proteins, and is increasingly implicated in the pathogenesis of MDS. Using single-cell gel electrophoresis, we have identified oxidized pyrimidine nucleotides in the progenitor-enriched bone marrow CD34⁺ compartment from MDS patients (P = 0.039), which are absent in both CD34^? MDS cells (P = 0.53) and also CD34⁺ cells from normal subjects (P = 0.55). MDS CD34⁺ blood cells also showed oxidized pyrimidine nucleotides compared with CD34^? cells (P = 0.029). Within normal subjects no differences were seen between CD34⁺ and CD34^? bone marrow cell compartments. CD34⁺ bone marrow cell oxidized pyrimidines were strongly associated with elevated plasma TNF-α and low bone marrow mononuclear cell glutathione concentrations (5/6 patients) and the inverse relationship was also found (3/4 patients). This data implies a role for intracellular oxygen free radical production, perhaps mediated by TNF-α, in the pathogenesis of ineffective haemopoiesis in MDS and provides a rationale for the bone marrow stimulatory effects of antioxidants such as Amifostine in MDS.     

Apical membrane protein 1‐specific antibody profile and temporal changes in peripheral blood B‐cell populations in Plasmodium vivax malaria

Plasmodium falciparum‐specific antibodies tend to be short‐lived, but their cognate memory B cells (MBCs) circulate in the peripheral blood of exposed subjects for several months or years after the last infection. However, the time course of antigen‐specific antibodies and B‐cell responses to the relatively neglected parasite Plasmodium vivax remains largely unexplored. Here, we showed that uncomplicated vivax malaria elicits short‐lived antibodies but long‐lived MBC responses to a major blood‐stage P vivax antigen, apical membrane protein 1 (PvAMA‐1), in subjects exposed to declining malaria transmission in the Amazon Basin of Brazil. We found that atypical (CD19⁺CD10^?CD21^?CD27^?) MBCs, which appear to share a common precursor with classical MBCs but are unable to differentiate into antibody‐secreting cells, significantly outnumbered classical MBCs by 5:1 in the peripheral blood of adult subjects currently or recently infected with P vivax and by 3:1 in healthy residents in the same endemic communities. We concluded that malaria can drive classical MBCs to differentiate into functionally impaired MBCs not only in subjects repeatedly exposed to P falciparum, but also in subjects living in areas with low levels of P vivax transmission in the Amazon, leading to an impaired B‐cell memory that may affect both naturally acquired and vaccine‐induced immunity.     

Immune response of γδT cells in Schistosome japonicum–infected C57BL/6 mouse liver

Systematic evaluation of the role of γδT cells during the Schistosoma japonicum infection has not been reported, despite the fact that γδT cells contribute to many infectious diseases in innate immunity. Therefore, the aim of this study was to observe the properties of γδT cells in the liver of C57BL/6 mice infected by S. japonicum. In this report, using immuno‐fluorescent histological analysis, γδT cells were found around hepatic granulomatous. Moreover, the flow cytometry results revealed that the percentage of hepatic γδT cells increased significantly after S. japonicum infection. More interestingly, a subset of CD3^?γδTCR⁺ cells were found and markedly increased after infection. Furthermore, expression of activation markers (CD25 and CD69) and cytokine profiles were detected in these hepatic CD3⁺γδTCR⁺and CD3^?γδTCR⁺ cells. The significantly higher level of CD69, IL‐4 and IL‐17 were observed in CD3⁺γδTCR⁺ cells after infection, suggesting that CD3⁺γδTCR⁺ cells instead of CD3^?γδTCR⁺ cells might play a predominant role during the infection. Finally, our results indicated that the expression of NKG2D on CD3⁺γδTCR⁺ cells was higher than that on CD3^?γδTCR⁺ cells. Collectively, γδT cells could play an important role in the liver of C57BL/6 mouse during japonicum infection.     

Transformed aggressive γδ‐variant T‐cell large granular lymphocytic leukemia with acquired copy neutral loss of heterozygosity at 17q11.2q25.3 and additional aberrations

T‐cell large granular lymphocytic leukemia (T‐LGLL) is a rare indolent lymphoproliferative disorder characterized by cytopenias, splenomegaly, and various degrees of T‐cell lymphocytosis, due to a clonal expansion of CD8‐positive cytotoxic T‐cells. Phenotypic variants of T‐LGLL include CD4⁺/CD8^? T‐cells, with dual CD4^?/CD8^?/γδ⁺ T‐cells being even rarer. Cytogenetic abnormalities in T‐LGLL have rarely been reported, and there is scientific debate regarding the existence of aggressive or transformed variants of T‐LGLL. We report a patient with T‐LGLL, γδ variant, with nearly 20‐year‐long duration of cytopenias before transformation to an unusual clinical scenario, manifesting with marked lymphocytosis >100 × 10⁹/L and infiltration of lymph nodes, tonsils, and subcutaneous tissue. Single‐nucleotide polymorphism assays revealed acquired copy neutral loss of heterozygosity at 17q and deletion of 3p21.31, in addition to trisomy 5, monosomy X, and monosomy 21. These genetic abnormalities provided a better understanding of the molecular nature and the potentiality of disease transformation.     

BCL6 rearrangement in a patient with mantle cell lymphoma

 We describe a patient with mantle cell lymphoma (MCL) associated with BCL6 gene rearrangement. MCL is a distinct subtype of non-Hodgkin's lymphoma characterized by CD5+, CD10–, CD20+, t(11;14)(q13;q32) and PRAD1/cyclin D1 overexpression. Although rearrangement of the BCL6 gene is the most frequent genetic change among diffuse lymphomas and some follicular lymphomas this is the first report of a patient with MCL associated with BCL6 rearrangement. Received: 6 January 1997 / Accepted: 17 February 1997     

T‐cell‐rich B‐cell lymphoma of the spleen presenting with severe hypersplenism

We report a 19‐year‐old woman who was presented with B‐symptoms, massive splenomegaly, hepatomegaly and hypersplenism. She underwent diagnostic/therapeutic splenectomy. Microscopically, the spleen showed a vaguely micronodular and diffuse proliferation of lymphoid cells in the white pulp that also involved the red pulp. On immunohistochemical staining, this proliferation consisted predominantly of CD3⁺, CD7⁺ small T cells with the presence of a minor populat?on of CD15^?,CD30^?, CD20⁺ large atypical B cells. A liver biopsy also showed a similar morphology to that seen in the spleen. After splenectomy, only the pancytopenia improved. A combined immunochemotherapy regimen (rituximab, cyclophosphamide, doxorubicin, vincristine and prednisolone) was utilized, which resulted in a complete remission.     

CD66c expression in B‐cell acute lymphoblastic leukemia: strength and weakness

Introduction: In B‐cell acute lymphoblastic leukemia (B‐ALL), testing at diagnosis for BCR/ABL1 gene rearrangements is mandatory for prognostic stratification and treatment decisions. Several diagnostic methods have been proposed using flow cytometry to identify BCR/ABL1⁺ B‐ALL. Methods: We evaluated expression of the myeloid antigen CD66c by flow cytometry in B‐ALL. We studied 94 patients with B‐ALL. The t(9;22)(q34;q11) or BCR/ABL1 rearrangement was detected by cytogenetic analysis or RT/PCR. Myeloid antigens CD66c, CD13, CD33, CD117, Myeloperoxidase, CD15 and CD65 were determined by flow cytometry. Results: Of these 94 cases, 17 (18%) cases displayed BCR/ABL1 gene rearrangements and 38 (40%) cases were CD66c positive. CD66c was the most common myeloid antigen expressed on malignant lymphoblasts. Its expression was correlated with BCR/ABL1 rearrangements (P = 0.0001): sensitivity 82%, specificity 69%, positive predictive value 37% and negative predictive value 95%. Co‐expression of CD66c⁺ CD13⁺ was more frequent in BCR/ABL1⁺ B‐ALL (29%) than BCR/ABL1^? cases (4%) (P = 0.0044). Some BCR/ABL1^? B‐ALL cases (including hyperdiploid or cases with normal karyotype) were CD66c positive (31%). Conclusion: CD66c expression is correlated, but not specifically, with BCR/ABL1 rearrangement. It would seem better to interpret the absence of CD66c expression with a lack of BCR/ABL1 rearrangement. This myeloid antigen could be interesting in the detection of minimal residual disease.     

Association between CD8+ T‐cell subsets and cardiovascular disease

Background

The findings of experimental studies suggest that the immune system plays a key role in atherosclerosis, but the clinical importance of different immune cells in cardiovascular disease remains poorly characterized. In this study we investigated the association between CD8⁺ T cells and carotid disease as well as development of cardiovascular disease events.

Methods

The study cohort comprised 700 subjects from the cardiovascular arm of the Malmö Diet and Cancer Study. Peripheral blood mononuclear cells, obtained at the 1991–1994 baseline investigation and stored at ?140 °C, were thawed and the different CD8⁺ T‐cell populations analysed by flow cytometry. Baseline carotid intima–media thickness and stenosis were assessed by ultrasonography and clinical events were monitored through validated national registers.

Results

Subjects with a high fraction of CD8⁺ T cells were characterized by decreased cytokine release from activated leucocytes, metabolic signs of insulin resistance and increased incidence of coronary events; hazard ratios (95% confidence intervals) for the second and third tertiles of CD8⁺ T cells were 2.57 (1.16, 5.67) and 2.61 (1.19, 5,71), respectively, in a Cox proportional hazards regression model. Correlations were found between the fraction of CD8⁺CD25⁺ T cells and the degree of carotid stenosis (r = 0.11, P < 0.01), and between the CD8⁺CD56^?IFN‐γ⁺ T‐cell fraction and the degree of stenosis (r = ?0.18, P < 0.005). The association between CD8⁺CD56^?IFN‐γ⁺ T cells and carotid stenosis remained significant after controlling for major cardiovascular disease risk factors.

Conclusion

This study provides prospective clinical evidence for a role of CD8⁺ T cells in cardiovascular disease and suggests the existence of CD8⁺ T‐cell subsets with different pathological functions.

     

A novel immunogenic CS1-specific peptide inducing antigen-specific cytotoxic T lymphocytes targeting multiple myeloma

The CS1 antigen provides a unique target for the development of an immunotherapeutic strategy to treat patients with multiple myeloma (MM). This study aimed to identify HLA‐A2⁺ immunogenic peptides from the CS1 antigen, which induce peptide‐specific cytotoxic T lymphocytes (CTL) against HLA‐A2⁺ MM cells. We identified a novel immunogenic HLA‐A2‐specific CS1_239‐247 (SLFVLGLFL) peptide, which induced CS1‐specific CTL (CS1‐CTL) to MM cells. The CS1‐CTL showed a distinct phenotype, with an increased percentage of effector memory and activated CTL and a decreased percentage of naïve CTL. CS1_239‐247 peptide‐specific CD8⁺ T cells were detected by DimerX analyses and demonstrated functional activities specific to the peptide. The CTL displayed HLA‐A2‐restricted and antigen‐specific cytotoxicity, proliferation, degranulation and γ‐interferon (IFN‐γ) production against both primary MM cells and MM cell lines. In addition, the effector memory cells subset (CD45RO⁺CCR7^?/CD3⁺CD8⁺) within CS1‐CTL showed a higher level of CD107a degranulation and IFN‐γ production as compared to effector cells (CD45RO^?CCR7^?/CD3⁺CD8⁺) against HLA‐A2⁺ primary MM cells or MM cell lines. In conclusion, this study introduced a novel immunogenic HLA‐A2‐specific CS1_239‐247 peptide capable of inducing antigen‐specific CTL against MM cells that will provide a framework for its application as a novel MM immunotherapy.     

Histone deacetylase inhibitors reduce VEGF production and induce growth suppression and apoptosis in human mantle cell lymphoma

OBJECTIVES: Mantle cell lymphoma (MCL) is an incurable disease with an aggressive course and novel treatment strategies are urgently needed. The purpose of this study was to evaluate the effects of histone deacetylase (HDAC) inhibitors, a new group of antiproliferative agents, on human MCL cells. METHODS: Three MCL cell lines (JeKo-1, Hbl-2 and Granta-519) were exposed to different concentrations of the HDAC inhibitors sodium butyrate (NaB) and suberoylanilide hydroxamic acid (SAHA) for 8-72 h. Their effects on cell viability, apoptosis induction and cell cycle proliferation were studied. Moreover, the influence of SAHA on the expression of cyclin D1, the cell cycle regulators p21 and p27 and the production of vascular endothelial growth factor (VEGF) were analyzed. RESULTS: The HDAC inhibitors induced accumulation of acetylated histones in MCL cells. MTT assays and Annexin-V staining showed that they potently inhibited viability in a dose-dependent manner and induced apoptosis in all cell lines tested. Cell cycle analysis indicated that their exposure to SAHA or NaB decreased the proportion of cells in S phase and increased the proportion of cells in the G0/G1 and/or G2/M phases. Incubation with the two HDAC inhibitors resulted in downregulation of cyclin D1. SAHA lead to an upregulation of p21 in all cell lines and an upregulation of p27 in JeKo-1 and Granta-519 cells, while expression of p27 in Hbl-2 was not altered. In addition, SAHA inhibited the production of the angiogenic cytokine VEGF. Treatment with NaB increased the expression of p21 in JeKo-1 and Hbl-2 cells, while in Granta 519 cells no effect was noted. The expression of p27 remained constant in all three cell lines after exposure to NaB. CONCLUSION: Based on these findings, we provide evidence that HDAC inhibitors have antiproliferative effects in MCL and may represent a promising therapeutic approach.     

Immunophenotypic analysis of T‐acute lymphoblastic leukemia. A CD5‐based ETP‐ALL perspective of non‐ETP T‐ALL

T‐cell antigens [CD5,CD1a,CD8] define early T‐cell precursor acute lymphoblastic leukemia (ETP‐ALL). To understand immature T‐ALL of which ETP‐ALL is part, we used these antigens to subcategorize non‐ETP T‐ALL for examining expression of myeloid/stem cell antigens (M/S) and clinical features. Using CD5 (+/?) to start categorization, we studied 69 routinely immunophenotyped patients with T‐ALL. CD5^? was a homogenous (CD8,CD1a)^? M/S⁺ ETP‐ALL group (n = 9). CD5⁺ cases were (CD8,CD1a)^? pre‐T‐ALL (n = 22) or (CD8,CD1a)⁺ (n = 38) thymic/cortical T‐ALL; M/S⁺ 20/22 (90.91%) in former and 22/38 (57.89%) in latter (P = 0.007). ETP‐ and pre‐T‐ALL together (CD1a^?,CD5^?/+ immature T‐ALL group) were nearly always M/S⁺ (29/31; 93.55%). In multivariate analysis, only ETP‐ALL predicted poor overall survival (P = 0.02). We conclude (i) CD5 negativity in T‐ALL almost always means ETP‐ALL. CD1a and CD8 negativity, as much as CD5, marks immaturity in T‐ALL, and the CD5^+/?/CD1a^?/CD8^? immature T‐ALL group needs further study to understand the biology of the T‐ALL–myeloid interface. (ii) ETP‐ALL patients may be pre‐T‐ALL if CD2⁺; CD2⁺, conversely, CD5^?/CD1a^?/CD8^? pre‐T ALL patients are ETP‐ALL. (iii) Immunophenotypic workup of T‐ALL must not omit CD1a, CD5, CD8 and CD2, and positivity of antigens should preferably be defined as recommended for ETP‐ALL, so that this entity can be better evaluated in future studies of immature T‐ALL, a group to which ETP‐ALL belongs. (iv) ETP‐ALL has poor prognosis.     

Persistent hepatitis C virus (HCV) infection impairs HCV‐specific cytotoxic T cell reactivity through Mcl‐1/Bim imbalance due to CD127 down‐regulation

Summary. In persistent hepatitis C virus (HCV) infection, HCV‐specific cytotoxic T lymphocyte (CTL) reactivity is impaired and this affects HCV control. Interleukin‐7 receptor (CD127) expression on these cells could regulate CTL reactivity through Mcl‐1/Bim balance modulation. Bim is a pro‐apoptotic molecule blocked by the action of Mcl‐1. Mcl‐1/Bim expression and T cell reactivity on HCV‐specific CTLs were compared according to CD127 phenotype. Peripheral blood lymphocytes (PBL) from HLA‐A2⁺ HCV⁺ patients were obtained. HCV‐specific CTLs were visualized by staining PBL with anti‐CD8 and HLA‐A2/peptide pentameric complexes (pentamer). Mcl‐1/Bim/CD127 phenotype of HCV‐specific CTLs was tested by staining detectable CD8⁺/pentamer⁺ cells with anti‐Mcl‐1/Bim/CD127 antibodies. HCV‐specific CTL proliferation ability after specific in vitro challenge was tested in the presence and absence of pancaspase inhibitor z‐VAD‐fmk. All stained cells were analysed by flow cytometry. CD127^low‐expressing HCV‐specific CTLs associated with high HCV viraemia, while CD127^high correlated with undetectable viral loads (P < 0.001). Directly ex vivo, pentamer⁺ cell frequency was similar according to CD127 expression level. Nevertheless, CD127^low pentamer⁺ cell proliferation after specific in vitro challenge was impaired (P < 0.05), although this was corrected by z‐VAD‐fmk treatment (P < 0.05). Mcl‐1 expression was low directly ex vivo (P < 0.01), and Bim was up‐regulated after antigen encounter (P < 0.05) of CD127^low pentamer⁺ cells. The ex vivo difference between Mcl‐1 and Bim expression on pentamer⁺ cells correlated positively with CD127 expression level (P < 0.001) and with pentamer⁺ cell reactivity (P < 0.05). In summary, a low ex vivo Mcl‐1 expression and Bim up‐regulation after antigen encounter are involved in CD127^low HCV‐specific CTL hyporeactivity during chronic infection, but it can be overcome by apoptosis blockade.     

The Bruton tyrosine kinase (BTK) inhibitor PCI‐32765 synergistically increases proteasome inhibitor activity in diffuse large‐B cell lymphoma (DLBCL) and mantle cell lymphoma (MCL) cells sensitive or resistant to bortezomib

Interactions between the Bruton tyrosine kinase (BTK) inhibitor PCI‐32765 and the proteasome inhibitor (bortezomib) were examined in diffuse large‐B cell lymphoma (DLBCL) and mantle cell lymphoma (MCL) cells, including those highly resistant to bortezomib. Co‐administration of PCI‐32765/bortezomib synergistically increased mitochondrial injury and apoptosis in germinal centre‐ or activated B‐cell‐like‐DLBCL cells and in MCL cells. These events were accompanied by marked AKT and nuclear factor (NF)‐κB (NFKB1) inactivation, down‐regulation of Mcl‐1 (MCL1), Bcl‐xL (BCL2L1), and XIAP, and enhanced DNA damage (e.g., γH2A.X formation) and endoplasmic reticulum (ER) stress. Similar interactions were observed in highly bortezomib‐resistant DLBCL and MCL cells, and in primary DLBCL cells. In contrast, PCI‐32765/bortezomib regimens displayed minimal toxicity toward normal CD34⁺ bone marrow cells. Transfection of DLBCL cells with a constitutively active AKT construct attenuated AKT inactivation and significantly diminished cell death, whereas expression of an NF‐κB “super‐repressor” (IκBα_ser34/36) increased both PCI‐32765 and bortezomib lethality. Moreover, cells in which the ER stress response was disabled by a dominant‐negative eIF2α construct were resistant to this regimen. Finally, combined exposure to PCI‐32765 and bortezomib resulted in more pronounced and sustained reactive oxygen species (ROS) generation, and ROS scavengers significantly diminished lethality. Given promising early clinical results for PCI‐32765 in DLBCL and MCL, a strategy combining BTK/proteasome inhibitor warrants attention in these malignancies.