Fresh Peripheral Blood Mononuclear Cells Research Articles

CADM1/TSLC1 Identifies HTLV-1-Infected Cells and Determines Their Susceptibility to CTL-Mediated Lysis.

Human T cell lymphotropic virus-1 (HTLV-1) primarily infects CD4+ T cells, causing inflammatory disorders or a T cell malignancy in 5% to 10% of carriers. The cytotoxic T lymphocyte (CTL) response is a key factor that controls the viral load and thus the risk of disease. The ability to detect the viral protein Tax in primary cells has made it possible to estimate the rate at which Tax-expressing infected cells are eliminated by CTLs in persistently infected people. However, most HTLV-1-infected cells are Tax–at a given time, and their immunophenotype is poorly defined. Here, we aimed to identify a cell-surface molecule expressed by both Tax+ and Tax–HTLV-1-infected cells and use it to analyse the CTL response in fresh peripheral blood mononuclear cells. Cell adhesion molecule 1 (CADM1/TSLC1) was the best single marker of HTLV-1 infection, identifying HTLV-1-infected cells with greater sensitivity and specificity than CD25, CCR4 or ICAM-1. CADM1+CD4+ T cells carried a median of 65% of proviral copies in peripheral blood. In a cohort of 23 individuals, we quantified the rate of CTL-mediated killing of Tax+ and Tax−CADM1+ cells. We show that CADM1 expression is associated with enhanced susceptibility of infected cells to CTL lysis: despite the immunodominance of Tax in the CTL response, Tax+CADM1– cells were inefficiently lysed by CTLs. Upregulation of the CADM1 ligand CRTAM on CD8+ T cells correlated with efficient lysis of infected cells. Tax–CADM1+ cells were lysed at a very low rate by autologous CTLs, however, were efficiently killed when loaded with exogenous peptide antigen. High expression of CADM1 on most HTLV-1-infected cells in the face of enhanced CTL counterselection implies that CADM1 confers a strong benefit on the virus.

Angiotensin II type 1 receptor blocker telmisartan induces apoptosis and autophagy in adult T‐cell leukemia cells

Adult T‐cell leukemia/lymphoma (ATL), an aggressive T‐cell malignancy that develops after long‐term infection with human T‐cell leukemia virus (HTLV‐1), requires new treatments. Drug repositioning, reuse of a drug previously approved for the treatment of another condition to treat ATL, offers the possibility of reduced time and risk. Among clinically available angiotensin II receptor blockers, telmisartan is well known for its unique ability to activate peroxisome proliferator‐activated receptor‐γ, which plays various roles in lipid metabolism, cellular differentiation, and apoptosis. Here, telmisartan reduced cell viability and enhanced apoptotic cells via caspase activation in ex vivo peripheral blood monocytes from asymptomatic HTLV‐1 carriers (ACs) or via caspase‐independent cell death in acute‐type ATL, which has a poor prognosis. Telmisartan also induced significant growth inhibition and apoptosis in leukemia cell lines via caspase activation, whereas other angiotensin II receptor blockers did not induce cell death. Interestingly, telmisartan increased the LC3‐II‐enriched protein fraction, indicating autophagosome accumulation and autophagy. Thus, telmisartan simultaneously caused caspase activation and autophagy. A hypertension medication with antiproliferation effects on primary and leukemia cells is intriguing. Patients with an early diagnosis of ATL are generally monitored until the disease progresses; thus, suppression of progression from AC and indolent ATL to acute ATL is important. Our results suggest that telmisartan is highly effective against primary cells and leukemia cell lines in caspase‐dependent and ‐independent manners, and its clinical use may suppress acute transformation and improve prognosis of patients with this mortal disease. This is the first report demonstrating a cell growth‐inhibitory effect of telmisartan in fresh peripheral blood mononuclear cells from leukemia patients.

The effect of cellular isolation and cryopreservation on the expression of markers identifying subsets of regulatory T cells

BackgroundThe role of CD4+ regulatory T cells (Tregs) and their subsets during HIV infection is controversial. Cryopreserved peripheral blood mononuclear cells (PBMC) are an important source for assessing number and function of Tregs. However, it is unknown if PBMC isolation and cryopreservation affect the expression of CD120b and CD39, markers that identify specific subsets of Tregs. MethodsHIV-uninfected (HIV−) and -infected (HIV+) men were randomly selected from the Multicenter AIDS Cohort Study (MACS). Percentages of CD120b+ and CD39+ Tregs measured by flow cytometry in whole blood and in corresponding fresh and cryopreserved PBMC were compared. ResultsPercentages of CD120b+ Tregs were significantly lower in a) fresh PBMC relative to whole blood, and b) freshly thawed frozen PBMC relative to fresh PBMC when the recovery of viable cryopreserved cells was low. When present, low expression of CD120b in frozen PBMC was reversible by 4h of in vitro culture. In contrast, expression of CD39 on Tregs was not affected by isolation and/or cryopreservation of PBMC, or by relative recovery of cryopreserved PBMC. These findings were unaffected by the HIV status of the donor. ConclusionThe data suggest that percentages of CD120b+ Tregs and CD39+ Tregs can be validly measured in either whole blood or PBMC (fresh and frozen) in HIV− and HIV+ men. However, for measurement of CD120b+ Tregs one type of sample should be used consistently within a given study, and thawed frozen cells may require in vitro culture if recovery of viable cells is low.

Standardization of cryopreserved peripheral blood mononuclear cells through a resting process for clinical immunomonitoring--Development of an algorithm.

Flow cytometry, as a powerful tool for immunomonitoring and quality control of peripheral blood mononuclear cells (PBMCs), is routinely used in clinical studies. However, flow cytometry based assays for cryopreserved peripheral blood mononuclear cells (cPBMCs) constitute a challenge. Down-regulation of surface and intracellular markers, as well as impairment of cell function might result from cryopreservation. Furthermore, protocols for resting cPBMCs are available but diverse. Therefore, we performed a standardization of the resting process concerning resting position, cell concentration, resting period and material of cell culture tubes as well as culture media. We further investigated the influence of resting on the phenotype and functionality of T cells comparing fresh PBMCs as gold standard to rested and non-rested cPBMCs. Polychromatic flow cytometry staining, peptide-MHC class I restricted tetramer staining and intracellular cytokine staining as major methods were used. Our results revealed that a horizontal position, a cell concentration of 2 to 5 × 10(6) cells/ml and an overnight resting phase is beneficial to eliminate dead or dying cells in cPBMCs with a mean cell loss of 14% overall cell populations. In addition, the quality and quantity of regulatory T cells and antigen specific T cells recovered upon resting. For multifunctional T cells a decrease of activation threshold in the way of a twofold mean fluorescence intensity (MFI) and increase of degranulation marker CD107a, co-stimulatory marker CD28, adhesion molecule CD62L as well as the ability to secrete antiviral cytokines like interferon gamma (IFN-γ), tumor necrosis factor (TNF), and interleukin 2 (IL-2) comparable to fresh PBMCs were observed. However, based upon our data resting is not helpful for the flow cytometric analyses of myeloid-derived suppressor cells (MDSCs) and large/intermediate size lymphocytes which rather decreased/vanished ex vivo. Therefore, we developed an algorithm to indicate for which cell population and for which type of analyses the resting process is useful or not.

Kinetics of human myeloid-derived suppressor cells after blood draw.

BackgroundHuman myeloid-derived suppressor cells (MDSC) have been described as a group of immature myeloid cells which exert immunosuppressive action by inhibiting function of T lymphocytes. While there is a huge scientific interest to study these cells in multiple human diseases, the methodological approach varies substantially between published studies. This is problematic as human MDSC seem to be a sensible cell type concerning not only cryopreservation but also time point after blood draw. To date data on delayed blood processing influencing cell numbers and phenotype is missing. We therefore evaluated the kinetics of granulocytic MDSC (gMDSC) and monocytic MDSC (mMDSC) frequencies after blood draw in order to determine the best time point for analysis of this recently defined cell type.MethodsIn this study, we isolated peripheral blood mononuclear cells (PBMC) of patients with HIV infection or solid tumors directly after blood draw. We then analyzed the frequencies of gMDSC and mMDSC 2, 4 and 6 h after blood draw and after an overnight rest by FACS analysis using the standard phenotypic markers. In addition, part of the cells was frozen directly after PBMC preparation and was measured after thawing.ResultsgMDSC levels showed no significant difference using fresh PBMC over time with a limitation for the overnight sample. However they were massively diminished after freezing (p = 0.0001 for all subjects). In contrast, frequencies of fresh mMDSC varied over time with no difference between time point 2 and 4 h but a significantly reduction after 6 h and overnight rest (p = 0.0005 and p = 0.005 respectively). Freezing of PBMC decreased the yield of mMDSC reaching statistical significance (p = 0.04). For both MDSC subgroups, FACS analysis became more difficult over time due to less sharp divisions between populations.ConclusionsAccording to our data human MDSC need to be studied on fresh PBMC. gMDSC can be studied with delay, mMDSC however should be studied no later than 4 h after blood draw. These results are crucial as an increasing number of clinical trials aim at analyzing MDSC nowadays and the logistics of blood processing implies delayed sample processing in some cases.Electronic supplementary materialThe online version of this article (doi:10.1186/s12967-015-0755-y) contains supplementary material, which is available to authorized users.

Abstract A089: The circulating memory B cell compartment of breast cancer patients is depleted in comparison with healthy volunteers

Abstract Background: Breast cancer is the most common cancer in women but fortunately 80% of those diagnosed with early disease survive without recurrence and those with advanced disease are living longer. It is now suspected that immune editing is a requisite hallmark of cancer but that the ongoing anti-tumour immune response, implied by tumour lymphocyte infiltration, can be a favourable prognostic feature. Little is known however about this equilibrium's impact on or from B Cells either within the tumour or in patient circulation. We therefore aimed to analyse the circulating mature memory B cell compartment in breast cancer patients to identify any changes detectable beyond the tumour environment. Methods: Between April 2014 and May 2015, 49 healthy volunteers (HVs) and 56 patients with breast cancer were recruited for analysis. Patients were recruited at all stages of disease and the treatment pathway, but none were within 3 weeks of either cytotoxic chemotherapy or radiotherapy. Fresh Peripheral Blood Mononuclear Cells (PBMCs) were extracted and analysed with multi-colour flow cytometry for markers of B lymphocyte differentiation (CD45/19/20/22/23/24/27/38). Subsequent B cell populations were compared between HVs and patients and also across recognised clinico-pathological parameters. Results: While patients were significantly older than HVs (mean age, 55.7 vs 44.4, p<0.0001), there was no correlation between age and the total B Cell proportion (r=-0.2642, p=0.07) or between age and the subset of greatest interest, memory B Cells (r= 0.1246, p=0.3938) amongst HVs. Patients predominantly were within a year of diagnosis (n=29, 51.8%), had early stage (stage 4, n=18, 32.1%), higher grade (grade 3, n=31, 55.4%), ER+ (n=41, 73.2%), breast cancer and the majority (n=42, 75%) had received cytotoxic chemotherapy. There was no significant difference between HVs and patients in the overall CD19+CD20+ B cell proportion of the CD45+ lymphocytes in blood (mean 6.32% vs 6.151%, p= 0.8269). Of the overall CD19+CD20+ B cell compartment, there were no significant differences in CD23+CD24+/- naive B cells (mean, 62.3% vs 61.05%, p=0.7419), or CD24+CD38++ regulatory B cells (mean, 2.33% vs 2.02%, p=0.6606) between patients and HVs. There was however a substantial depletion of the CD22+CD27+ memory B Cell compartment in patients (mean, 6.31% vs 12.6%, p<0.0001). This difference was apparent both at early (stage 2/3), advanced (stage 4), Grade 2 or 3, ER negative and positive breast cancer groups and, also, for those with early disease, both within a year and longer since their diagnosis. Whilst non-significant, there was a strong suggestion that patients who had received cytotoxic chemotherapy had a smaller memory B cell component than those who did not (mean, 5.90% vs 8.85%, p=0.0531). This effect, if true, seems to be maintained with time, as those who had received chemotherapy less than (mean, 6.56% vs 12.64%, p< 0.0001) as well as those who had received chemotherapy for more than a year (mean, 4.99% vs 12.64%, p<0.0001) prior to analysis had depressed memory B cell components when compared with HVs. Conclusions: Breast cancer patients, across pathological subtypes, seem to have a preserved total B cell count as a proportion of total peripheral blood mononuclear cells, but have a selectively depleted circulating memory B cell compartment when compared with the equivalent memory B cell compartment of healthy volunteers. Whether this effect is part of an immuno-editing phenomenon or the result of cancer treatment remains uncertain but warrants further investigation. Analysing the antigen reactivity and clonal expansion or function of this memory B cell compartment may yield insights into whether a normal immune, or even anti-tumour, memory response is retained in breast cancer. Citation Format: Matthew W. Fittall, Dina Levi, Angela Clifford, Vandna Shah, Anthony Cheung, Andrew Tutt, Sophia N. Karagiannis. The circulating memory B cell compartment of breast cancer patients is depleted in comparison with healthy volunteers. [abstract]. In: Proceedings of the CRI-CIMT-EATI-AACR Inaugural International Cancer Immunotherapy Conference: Translating Science into Survival; September 16-19, 2015; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2016;4(1 Suppl):Abstract nr A089.

Leukoreduction system chambers provide a valuable source of functional monocytes for the monocyte activation test by comparison with internationally validated methods

Despite being added to the European Pharmacopoeia in 2010 and strongly supported by the European directive enforcing the “3R's” — Replace, Reduce and Refine, uptake of the monocyte activation test (MAT) in preference over the rabbit pyrogen test for the detection of pyrogens has been limited. This has been attributed to the difficulty in sourcing human monocytes due to the necessity of phlebotomy. This study has attempted to address this issue by evaluating cryopreserved peripheral blood mononuclear cells (PBMCs) isolated from leukoreduction system chambers (LRSCs), a readily available by-product of platelet apheresis, as a source of monocytes for the MAT. Validation was performed by direct comparison with the two most commonly employed primary monocyte sources: fresh whole blood (WB) and PBMCs from fresh blood, assessing their ability to detect a panel of toll-like receptor (TLR) ligands including Pam3CSK4, Lipoteichoic acid, Peptidoglycan, Poly(I:C) and Flagellin, as well as two different endotoxin sources, with IL-1β and IL-6 as the readouts. All three cell sources were able to detect the pyrogens included in the study with comparable sensitivities, with the exception of TLR3 ligand Poly(I:C). The WB assay produced quantifiable, but significantly lower cytokine levels with every pyrogen tested than either of the PBMCs sources used. LRSCs provided an ample and convenient source of PBMCs which were successfully cryopreserved, providing cell banks for each donor, shown to maintain stability for at least a year. The use of cryopreserved PBMCs reduced the time and effort required to set up an assay, and the availability of single donor cell banks will allow investigations into assay variables in the absence of inter-donor variability. Significantly higher sensitivity to Pam3CSK4 was observed with a proportion of donors. This was found to correlate to single nucleotide polymorphisms rs4833095 and rs5743618 of TLR1. This evidence, along with the wide range of other SNPs identified in TLR regions without known biological function, supports caution in the practice of pooling donor cells in order to overcome donor-to-donor variation.

Automated Lentiviral Transduction of T Cells with Cars Using the Clinimacs Prodigy

BACKGROUNDGenetically modified T cells have enormous potential for the treatment of relapsed and refractory haematopoietic malignancies. CD19-positive B-cell malignancies including acute lymphoblastic leukaemia (ALL), chronic lymphocytic leukaemia (CLL) or B cell non-Hodgkin lymphomas (NHL) have been shown to be an excellent target for adoptive immunotherapy with T cells expressing CD19-specific chimeric antigen receptors (CARs). The increasing need for genetically modified T cells is hampered by the limited number of centres with the required infrastructure and expertise to produce this complex therapeutic product. Ex vivo modification of T cells requires isolation, activation, transduction, expansion and cryopreservation steps. To simplify procedures and widen applicability for clinical therapies, Miltenyi Biotec has developed the CliniMACS Prodigy platform and is automating complex cell manufacturing processes. These have now been adapted for lentiviral transduction of T cells and we show the feasibility and effectiveness of the device for adoptive immunotherapy using chimeric antigen receptors.METHODSA self-inactivating third generation lentiviral vector encoding a CAR specific for CD19 (CAR19) was used for automated T-cell transductions (TCT). Using closed single-use tubing sets (TS520), fresh or cryopreserved peripheral blood mononuclear cells from non-mobilised leukapheresis collected from healthy donors were loaded onto the CliniMACS Prodigy, washed and activated in TexMACS media with TransAct, a polymeric nanomatrix activation reagent agonist for CD3 and CD28. Cells were transduced 24-48h after activation and expanded in the CentriCult-Unit of the tubing set, allowing for stable culture conditions as well as automated feeding and media exchange. Small and large scale comparison transductions were run in parallel to assess the efficiency of the automated T-cell modification. Finally, cells were harvested and cryopreserved to assess the functional capabilities of CAR19 T cells.RESULTSThree automated TCT runs were performed and continuously monitored to assess cell expansion, transduction efficiency and the phenotype of the final cell product. On average, expansion during automated cultivation was 11.7x (range: 5.4 - 22.8x) which was comparable to the expansion achieved in small scale controls (12.3x ± 1.2x). The average yield from the automated process was 11.8x108 total lymphocytes/run (ranging between 4 - 23.2x108 lymphocytes/run). Notably, this was comparable to existing CAR19 T cell manufacturing processes using a WAVE-Bioreactor. In all three runs in the Prodigy, successful transduction was observed with an average transduction efficiency of 32% CAR19-positive cells (range: 22- 45%). Again, this was similar to transduction efficiencies (32% CAR19-positive; range: 27-40%) in previous WAVE-production campaigns using X-Vivo15 media and magnetic beads conjugated with anti-CD3/CD28 antibodies for T-cell activation (Dynabeads). Flow cytometry analysis of the final cell product showed a high purity of CD45+/CD3+ cells (90%) as well as a relatively high frequency of CD8-positive cytotoxic T cells (56%). Immunophenotyping revealed high expression of CD45RA, CD62L, CD27 and CD95 with moderate expression of CCR7. Importantly, no significant difference in PD-1 expression was observed between automatically and manually processed cells. Finally, functional analysis showed cytotoxic activity as well as IFN-γ/TNF-α production upon co-cultivation with CD19-expressing target cells.CONCLUSIONIn summary, we have demonstrated the feasibility of the CliniMACS Prodigy for the generation of CAR+ T cells for adoptive immunotherapy. Automated activation, transduction and expansion resulted in clinically relevant doses of CAR19 T cells with very little 'hands-on' operator time. Given the closed-system nature of the device, and automated features, the CliniMACS Prodigy should widen applicability of T-cell engineering beyond centres with highly specialised infrastructures. DisclosuresMock*:Miltenyi Biotec GmbH: Research Funding. Nickolay*:Miltenyi Biotec GmbH: Research Funding. Peggs:Cellectis: Research Funding; Autolus: Consultancy, Equity Ownership. Johnston:Miltenyi Biotec GmbH: Employment. Kaiser:Miltenyi Biotec GmbH: Employment. Pule:CELLECTIS: Research Funding; AUTOLUS: Employment, Equity Ownership, Research Funding; AMGEN: Honoraria; UCLB: Patents & Royalties. Thrasher:Miltenyi Biotec GmbH: Research Funding; Autolus Ltd: Consultancy, Equity Ownership, Research Funding. Qasim:Cellectis: Research Funding; Miltenyi Biotec GmbH: Research Funding; Autolus Ltd: Consultancy, Equity Ownership, Research Funding; Cell Medica: Research Funding.

Immune cell subsets and their gene expression profiles from human PBMC isolated by Vacutainer Cell Preparation Tube (CPT™) and standard density gradient.

BackgroundHigh quality genetic material is an essential pre-requisite when analyzing gene expression using microarray technology. Peripheral blood mononuclear cells (PBMC) are frequently used for genomic analyses, but several factors can affect the integrity of nucleic acids prior to their extraction, including the methods of PBMC collection and isolation. Due to the lack of the relevant data published, we compared the Ficoll-Paque density gradient centrifugation and BD Vacutainer cell preparation tube (CPT) protocols to determine if either method offered a distinct advantage in preparation of PBMC-derived immune cell subsets for their use in gene expression analysis. We evaluated the yield and purity of immune cell subpopulations isolated from PBMC derived by both methods, the quantity and quality of extracted nucleic acids, and compared gene expression in PBMC and individual immune cell types from Ficoll and CPT isolation protocols using Affymetrix microarrays.ResultsThe mean yield and viability of fresh PBMC acquired by the CPT method (1.16 × 106 cells/ml, 93.3 %) were compatible to those obtained with Ficoll (1.34 × 106 cells/ml, 97.2 %). No differences in the mean purity, recovery, and viability of CD19+ (B cells), CD8+ (cytotoxic T cells), CD4+ (helper T cell) and CD14+ (monocytes) positively selected from CPT- or Ficoll-isolated PBMC were found. Similar quantities of high quality RNA and DNA were extracted from PBMC and immune cells obtained by both methods. Finally, the PBMC isolation methods tested did not impact subsequent recovery and purity of individual immune cell subsets and, importantly, their gene expression profiles.ConclusionsOur findings demonstrate that the CPT and Ficoll PBMC isolation protocols do not differ in their ability to purify high quality immune cell subpopulations. Since there was no difference in the gene expression profiles between immune cells obtained by these two methods, the Ficoll isolation can be substituted by the CPT protocol without conceding phenotypic changes of immune cells and compromising the gene expression studies. Given that the CPT protocol is less elaborate, minimizes cells’ handling and processing time, this method offers a significant operating advantage, especially in large-scale clinical studies aiming at dissecting gene expression in PBMC and PBMC-derived immune cell subpopulations.Electronic supplementary materialThe online version of this article (doi:10.1186/s12865-015-0113-0) contains supplementary material, which is available to authorized users.

Peripheral Blood Mononuclear Cells Enhance Cartilage Repair in in vivo Osteochondral Defect Model.

This study characterized peripheral blood mononuclear cells (PBMC) in terms of their potential in cartilage repair and investigated their ability to improve the healing in a pre-clinical large animal model. Human PBMCs were isolated with gradient centrifugation and adherent PBMC’s were evaluated for their ability to differentiate into adipogenic, chondrogenic and osteogenic lineages and also for their expression of musculoskeletal genes. The phenotype of the PBMCs was evaluated using Stro-1, CD34, CD44, CD45, CD90, CD106, CD105, CD146 and CD166 cell surface markers. Osteochondral defects were created in the medial femoral condyle (MFC) of 24 Welsh mountain sheep and evaluated at a six month time point. Four cell treatment groups were evaluated in combination with collagen-GAG-scaffold: (1) MSC alone; (2) MSCs and PBMCs at a ratio of 20:1; (3) MSCs and PBMC at a ratio of 2:1 and (4) PBMCs alone. Samples from the surgical site were evaluated for mechanical properties, ICRS score and histological repair. Fresh PBMC samples were 90% positive for hematopoietic cell surface markers and negative for the MSC antibody panel (<1%, p = 0.006). However, the adherent PBMC population expressed mesenchymal stem cell markers in hypoxic culture and lacked CD34/45 positive cells (<0.2%). This finding demonstrated that the adherent cells had acquired an MSC-like phenotype and transformed in hypoxia from their original hematopoietic lineage. Four key genes in muskuloskeletal biology were significantly upregulated in adherent PBMCs by hypoxia: BMP2 4.2-fold (p = 0.0007), BMP6 10.7-fold (p = 0.0004), GDF5 2.0-fold (p = 0.002) and COL1 5.0-fold (p = 0.046). The monolayer multilineage analysis confirmed the trilineage mesenchymal potential of the adherent PBMCs. PBMC cell therapy was equally good as bone marrow MSC therapy for defects in the ovine large animal model. Our results show that PBMCs support cartilage healing and oxygen tension of the environment was found to have a key effect on the derivation of a novel adherent cell population with an MSC-like phenotype. This study presents a novel and easily attainable point-of-care cell therapy with PBMCs to treat osteochondral defects in the knee avoiding any cell manipulations outside the surgical room.

Repeated Injections of IL-2 Break Renal Allograft Tolerance Induced via Mixed Hematopoietic Chimerism in Monkeys.

Tolerance of allografts achieved in mice via stable mixed hematopoietic chimerism relies essentially on continuous elimination of developing alloreactive T cells in the thymus (central deletion). Conversely, while only transient mixed chimerism is observed in nonhuman primates and patients, it is sufficient to ensure tolerance of kidney allografts. In this setting, it is likely that tolerance depends on peripheral regulatory mechanisms rather than thymic deletion. This implies that, in primates, upsetting the balance between inflammatory and regulatory alloimmunity could abolish tolerance and trigger the rejection of previously accepted renal allografts. In this study, six monkeys that were treated with a mixed chimerism protocol and had accepted a kidney allograft for periods of 1-10 years after withdrawal of immunosuppression received subcutaneous injections of IL-2 cytokine (0.6-3 × 10(6) IU/m(2) ). This resulted in rapid rejection of previously tolerated renal transplants and was associated with an expansion and reactivation of alloreactive pro-inflammatory memory T cells in the host's lymphoid organs and in the graft. This phenomenon was prevented by anti-CD8 antibody treatment. Finally, this process was reversible in that cessation of IL-2 administration aborted the rejection process and restored normal kidney graft function.

Characterization of effector and memory T cell subsets in the immune response to bovine tuberculosis in cattle.

Cultured IFN-γ ELISPOT assays are primarily a measure of central memory T cell (Tcm) responses with humans; however, this important subset of lymphocytes is poorly characterized in cattle. Vaccine-elicited cultured IFN-γ ELISPOT responses correlate with protection against bovine tuberculosis in cattle. However, whether this assay measures cattle Tcm responses or not is uncertain. The objective of the present study was to characterize the relative contribution of Tcm (CCR7+, CD62Lhi, CD45RO+), T effector memory (Tem, defined as: CCR7-, CD62Llow/int, CD45RO+), and T effector cells (CCR7-, CD62L-/low, CD45RO-), in the immune response to Mycobacterium bovis. Peripheral blood mononuclear cells (PBMC) from infected cattle were stimulated with a cocktail of M. bovis purified protein derivative, rTb10.4 and rAg85A for 13 days with periodic addition of fresh media and rIL-2. On day 13, cultured PBMC were re-stimulated with medium alone, rESAT-6:CFP10 or PPDb with fresh autologous adherent cells for antigen presentation. Cultured cells (13 days) or fresh PBMCs (ex vivo response) from the same calves were analyzed for IFN-γ production, proliferation, and CD4, CD45RO, CD62L, CD44, and CCR7 expression via flow cytometry after overnight stimulation. In response to mycobacterial antigens, ~75% of CD4+ IFN-γ+ cells in long-term cultures expressed a Tcm phenotype while less than 10% of the ex vivo response consisted of Tcm cells. Upon re-exposure to antigen, long-term cultured cells were highly proliferative, a distinctive characteristic of Tcm, and the predominant phenotype within the long-term cultures switched from Tcm to Tem. These findings suggest that proliferative responses of Tcm cells to some extent occurs simultaneously with reversion to effector phenotypes (mostly Tem). The present study characterizes Tcm cells of cattle and their participation in the response to M. bovis infection.

Upregulation of FcγRIIb on monocytes is necessary to promote the superagonist activity of TGN1412

AbstractThe anti-CD28 superagonist antibody TGN1412 caused life-threatening cytokine release syndrome (CRS) in healthy volunteers, which had not been predicted by preclinical testing. T cells in fresh peripheral blood mononuclear cells (PBMCs) do not respond to soluble TGN1412 but do respond following high-density (HD) preculture. We show for the first time that this response is dependent on crystallizable fragment gamma receptor IIb (FcγRIIb) expression on monocytes. This was unexpected because, unlike B cells, circulating monocytes express little or no FcγRIIb. However, FcγRIIb expression is logarithmically increased on monocytes during HD preculture, and this upregulation is necessary and sufficient to explain TGN1412 potency after HD preculture. B-cell FcγRIIb expression is unchanged by HD preculture, but B cells can support TGN1412-mediated T-cell proliferation when added at a frequency higher than that in PBMCs. Although low-density (LD) precultured PBMCs do not respond to TGN1412, T cells from LD preculture are fully responsive when cocultured with FcγRIIb-expressing monocytes from HD preculture, which shows that they are fully able to respond to TGN1412-mediated activation. Our novel findings demonstrate that cross-linking by FcγRIIb is critical for the superagonist activity of TGN1412 after HD preculture, and this may contribute to CRS in humans because of the close association of FcγRIIb-bearing cells with T cells in lymphoid tissues.

A Profound Decrease in FoxP3+Helios+CD4+ T Cells in a Subset of Patients with Acquired Aplastic Anemia and Pure Red Cell Aplasia: A Common Mechanism Underlying a Dependency on Cyclosporine

Background: A subset of patients with acquired aplastic anemia (AA) require low-dose cyclosporine (CsA) to maintain good hematopoietic function even after achieving a remission with immunosuppressive therapy (IST). Such CsA-dependent AA offers opportunities to clarify the immune mechanisms underlying bone marrow (BM) failure, but little is known about the mechanism(s) underlying this condition except for its close association with a particular HLA-class II allele DRB1*15:01. Regulatory T cells (Tregs), defined as CD4+CD25highFoxP3+ T cells, have been shown to be decreased in patients with severe AA at diagnosis and to recover to normal levels in association with hematological recovery after successful IST. An insufficient Treg recovery may account for dependency on CsA in a particular subset of AA patients, and also in patients with idiopathic pure red cell aplasia (PRCA), another typical immune-mediated BM failure of which remission is known to depend on CsA in virtually all patients. To test this hypothesis, we determined the percentage and absolute number of Tregs, as well as Th1, Th2 and Th17 cells, in various types of immune-mediated BM failure, using an anti-FoxP3 antibody (Ab) and anti-Helios Ab that allows enumeration of the functional Tregs more precisely than conventional methods. Methods: Different CD4+ Treg subsets were enumerated using a multicolor flow cytometry assay. Peripheral blood mononuclear cells (PBMCs) were stimulated by phorbol myristate acetate (PMA) and ionomycin in the presence of monensin for four hours, then were subjected to flow cytometry to determine the percentage of CD4+ T cells positive for cytoplasmic interferon-γ (Th1), interleukin 4 (Th2) and interleukin 17 (Th17). CsA-dependent AA was defined as AA with two or more episodes of relapse of pancytopenia that occurred during more than one year of therapy, followed by a good response to CsA. All six patients with CsA-dependent AA had normal blood cell counts and HLA-DR15 (DRB1*15:01 in five and DRB1*15:02 in one). Results: The normal ranges of each T cell subset percentage and the absolute numbers determined in 47 healthy volunteers (HVs) were: FoxP3+Helios+ Tregs 6.5±1.6%/ 47.7±13.8/µl, Th1 22.3±6.6%/ 151.2± 45.5/µl, Th2 5.5±1.6%/ 38.3±170.9/µl and Th17 1.7± 0.7%/ 11.2± 4.7/µl. The expression of FoxP3 by CD4+ T cells decreased with time after sampling, and this assay therefore necessitated analyses within 16 hours after sampling using fresh PBMCs. Compared to healthy volunteers, the percentage and absolute number of FoxP3+Helios+ Treg cells were significantly lower in the five patients with severe AA at diagnosis (3.7±1.1%, 22.7±6.8/µl) and in six CsA-dependent AA patients (3.4±0.8%, 13.8±12.3/µl) (Figure). In contrast, the Treg percentages were comparable to those of the HVs in four AA patients on CsA in convalescence (5.8±1.0%) and nine patients in remission off CsA (6.3±1.1%) while the absolute numbers of FoxP3+Helios+Tregs (27.3±19.2/µl, 32.3±13.3/µl) in these groups were lower than those of the HVs. On the other hand, the percentages of all other CD4+ T cell subsets were comparable among the four different groups and HVs. The apparent decrease in FoxP3+Helios+ Tregs despite normal blood cell counts in patients with CsA-dependent AA prompted us to screen nine patients with idiopathic PRCA whose erythropoietic functions were all dependent on CsA. The FoxP3+Helios+ Tregs were decreased in both the percentage and absolute count (3.1±0.5%, 12.1±5.9/µl) in all of these patients, including two patients whose PBMCs were examined before CsA therapy. As a result, the ratios of Th1/Treg and Th17/Treg were markedly higher in newly-diagnosed AA (12.5±3.4, 0.9±0.8), CsA-dependent AA (12.6±12.1, 1.1±1.5) and PRCA (10.6±7.7, 0.7±0.3) patients than in AA patients in convalescence (6.1±4.3, 0.4±0.1) and those in remission (3.8±2.3, 0.4±0.2), which were comparable to the HVs Th1/Treg and Th17/Treg ratios (3.3±0.9, 0.3±0.2). Conclusions: Decreased percentages and absolute counts of Tregs, as well as increased Th1/Treg and Th17/Treg ratios, are common features in patients with CsA-dependent AA and PRCA. A persistent decrease in Tregs may serve as a good marker for predicting AA relapse in patients responding to CsA. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Phenotype alterations in regulatory T-cell subsets in primary HIV infection and identification of Tr1-like cells as the main interleukin 10-producing CD4+ T cells.

Conventional regulatory T cells (Tregs) can suppress human immunodeficiency virus type 1 (HIV-1)-specific immune responses but cannot control immune activation in primary HIV infection. Here, we characterized Treg subsets, using recently defined phenotypic delineation, and analyzed the relative contribution of cell subsets to the production of immunosuppressive cytokines in primary HIV infection. In a longitudinal prospective study, ex vivo phenotyping of fresh peripheral blood mononuclear cells from patients with primary HIV infection was performed at baseline and month 6 of follow-up to characterize Treg subsets, immune activation, and cytokine production in isolated CD4(+) T cells. The frequency of CD4(+)CD25(+)CD127(low) Tregs and the distribution between the naive, memory, and activated/memory Treg subsets was similar in patients and healthy donors. However, Tregs from patients with primary HIV infection showed peculiar phenotypic profiles, such as elevated FoxP3, ICOS, and CTLA-4 expression, with CTLA-4 expression strikingly increased in all Treg subsets both at baseline and month 6 of follow-up. The great majority of interleukin 10 (IL-10)-producing CD4(+) T cells were FoxP3(neg) (ie, Tr1-like cells). In contrast to conventional Tregs, Tr1-like cells were inversely correlated with immune activation and not associated with lower effector T-cell responses. FoxP3(neg) Tr1-like cells-major contributors to IL-10 production-may have a beneficial role by controlling immune activation in early HIV infection.

The role of CD40 expression in dendritic cells in cancer biology; a systematic review.

CD40 is a co-stimulatory molecule belonging to the tumor necrosis factor superfamily and is essential in activation of dendritic cells. Dendritic cells (DCs) are antigen-presenting cells capable of initiating cytotoxic T-lymphocyte immune response against cancer cells. However, there are few studies on the characterization of DCs in cancer, specifically their expression of CD40, despite its implication in cancer immunotherapy. We reviewed available data on the expression of CD40 on DCs in various cancers, and its implications for cancer immunotherapy. A systematic review on CD40 expression on DCs in cancer was performed with reference to preferred reporting items for systematic reviews and meta-analyses (PRISMA). Studies that satisfied the inclusion and exclusion criteria were 21 out of 927. Variations in type and status of the cancers, source of DCs and methodology for detecting CD40 expression amongst the studies resulted in contrasting results. DCs generally expressed low CD40 in tumor infiltrating DCs (tiDCs), in DCs derived by in vitro culture from blood monocytes using cytokine stimulation (MoDCs) and in DCs exposed in vitro to tumor cells lines; the studies suggested that CD40 expression in DCs is impaired in cancer particularly in metastatic disease. However, DCs identified in fresh peripheral blood mononuclear cells (PBMC) expressed higher numbers of CD40 positive cells in some cancer patients, which could be due to tumor-derived factors leading to partially-stimulated DCs. The results provide evidence that some cancer patients may show partial systemic DC activation and expression of increased CD40 in response to the presence of tumor but that such activity may become abortive in the presence of factors produced by the tumor. This review has thus identified key papers on CD40 expression on DCs in various cancers and discusses the limitations and contrasting results of these studies in relation to variations in methodology. The results highlight the need for further studies on the role of CD40-CD40 ligand pathway to inform cancer treatment.

Purification of regulatory T cells with the use of a fully enclosed high-speed microfluidic system

Background aimsDespite promising advances in cellular therapies, it will be difficult to fully test or implement new therapies until advances are made in the processes for cell preparation. This study describes the use of an advanced prototype of a flow-cytometry cell purification system constructed for operation in a clinical environment to prepare regulatory T cells defined as CD4+/CD25bright/CD127neg/low. MethodsThe sort performance of the Gigasort system was directly compared with available droplet sorters using mixtures of highly fluorescent and non-fluorescent 5-μm polystyrene particles. CD4+-enriched cell preparations were processed with the use of a sterile, disposable fluid handling unit with a chip containing parallel microfluidic-based sorters. ResultsSimilar purity and sort efficiency as found with droplet sorters were obtained with the 24-channel chip sorter system. Starting with 450 million fresh peripheral blood mononuclear cells, 150,000 to 1.7 million cells that were, on average, 85% FoxP3-positive and 97% viable, were obtained in <4 h. ConclusionsThis study presents a technology adapted to regulatory requirements for clinical cell purification and that achieves high throughput and cell-friendly conditions by use of a microfluidic chip with 24 parallel microsorters, providing a rapid, sterile method of purifying regulatory T cells accurately and with excellent viability.

The Center for HIV/AIDS Vaccine Immunology (CHAVI) multi-site quality assurance program for cryopreserved Human Peripheral Blood Mononuclear Cells

The Center for HIV/AIDS Vaccine Immunology (CHAVI) consortium was established to determine the host and virus factors associated with HIV transmission, infection and containment of virus replication, with the goal of advancing the development of an HIV protective vaccine. Studies to meet this goal required the use of cryopreserved Peripheral Blood Mononuclear Cell (PBMC) specimens, and therefore it was imperative that a quality assurance (QA) oversight program be developed to monitor PBMC samples obtained from study participants at multiple international sites. Nine site-affiliated laboratories in Africa and the USA collected and processed PBMCs, and cryopreserved PBMC were shipped to CHAVI repositories in Africa and the USA for long-term storage. A three-stage program was designed, based on Good Clinical Laboratory Practices (GCLP), to monitor PBMC integrity at each step of this process. The first stage evaluated the integrity of fresh PBMCs for initial viability, overall yield, and processing time at the site-affiliated laboratories (Stage 1); for the second stage, the repositories determined post-thaw viability and cell recovery of cryopreserved PBMC, received from the site-affiliated laboratories (Stage 2); the third stage assessed the long-term specimen storage at each repository (Stage 3). Overall, the CHAVI PBMC QA oversight program results highlight the relative importance of each of these stages to the ultimate goal of preserving specimen integrity from peripheral blood collection to long-term repository storage.

Increased expressions of NKp44, NKp46 on NK/NKT-like cells are associated with impaired cytolytic function in self-limiting hepatitis E infection

We have characterized the NK/NKT-like cells in patients with self-limiting hepatitis E infection. The distribution of peripheral NK/NKT-like cells, expressions of activation receptors, cytotoxic potential and effector function of NK/NKT-like cells from fresh peripheral blood mononuclear cells of 86 acute patients, 101 recovered and 54 control individuals were assessed. Activated NKT-like (CD16(+) CD56(+) CD3(+)) cells were high in the patient groups. On CD56(+) CD3(-) cells, NKp44 and NKp46 expressions were high in the acute patients, whereas NKp30, NKp44, NKp46 and NKG2D were high in the recovered individuals. On CD56(+) CD3(+) cells, NKp44, NKp46 and NKG2D expressions were high in the recovered but NKp30 was low in both the patient groups. Collectively, the current study elucidates the role of NK/NKT-like cells demonstrating phenotypic alterations of activated NKT-like cells and activation receptors, lack of CD107a expression and functional impairment of peripheral NK/NKT-like cells in self-limiting hepatitis E infection.

Expansion of NK cells by engineered K562 cells co-expressing 4-1BBL and mMICA, combined with soluble IL-21

NK cells hold promise for protecting hosts from cancer and pathogen infection through direct killing and expressing immune-regulatory cytokines. In our study, a genetically modified K562 cell line with surface expression of 4-1BBL and MICA was constructed to expand functional NK cells in vitro for further adoptive immunotherapy against cancer. After a long-term up to 21day co-culture with newly isolated peripheral blood mononuclear cells (PBMCs) in the presence of soluble IL-21 (sIL-21), notable increase in proportion of expanded NK cells was observed, especially the CD56brightCD16+ subset. Apparent up-regulation of activating receptors CD38, CD69 and NKG2D was detected on expanded NK cells, so did inhibitory receptor CD94; the cytotoxicity of expanded NK cells against target tumor cells exceeded that of NK cells within fresh PBMCs. The intracellular staining showed expanded NK cells produced immune-regulatory IFN-γ. Taken together, we expanded NK cells with significant up-regulation of activating NKG2D and moderate enhancement of cytotoxicity, with IFN-γ producing ability and a more heterogeneous population of NK cells. These findings provide a novel perspective on expanding NK cells in vitro for further biology study and adoptive immunotherapy of NK cells against cancer.