-
Nature Sep 2016Chronic viral infections are characterized by a state of CD8 T-cell dysfunction that is associated with expression of the programmed cell death 1 (PD-1) inhibitory...
Chronic viral infections are characterized by a state of CD8 T-cell dysfunction that is associated with expression of the programmed cell death 1 (PD-1) inhibitory receptor. A better understanding of the mechanisms that regulate CD8 T-cell responses during chronic infection is required to improve immunotherapies that restore function in exhausted CD8 T cells. Here we identify a population of virus-specific CD8 T cells that proliferate after blockade of the PD-1 inhibitory pathway in mice chronically infected with lymphocytic choriomeningitis virus (LCMV). These LCMV-specific CD8 T cells expressed the PD-1 inhibitory receptor, but also expressed several costimulatory molecules such as ICOS and CD28. This CD8 T-cell subset was characterized by a unique gene signature that was related to that of CD4 T follicular helper (T) cells, CD8 T cell memory precursors and haematopoietic stem cell progenitors, but that was distinct from that of CD4 T1 cells and CD8 terminal effectors. This CD8 T-cell population was found only in lymphoid tissues and resided predominantly in the T-cell zones along with naive CD8 T cells. These PD-1CD8 T cells resembled stem cells during chronic LCMV infection, undergoing self-renewal and also differentiating into the terminally exhausted CD8 T cells that were present in both lymphoid and non-lymphoid tissues. The proliferative burst after PD-1 blockade came almost exclusively from this CD8 T-cell subset. Notably, the transcription factor TCF1 had a cell-intrinsic and essential role in the generation of this CD8 T-cell subset. These findings provide a better understanding of T-cell exhaustion and have implications in the optimization of PD-1-directed immunotherapy in chronic infections and cancer.
Topics: Animals; CD28 Antigens; CD8-Positive T-Lymphocytes; Cell Differentiation; Cell Proliferation; Cell Self Renewal; Female; Hematopoietic Stem Cells; Hepatocyte Nuclear Factor 1-alpha; Immunotherapy; Inducible T-Cell Co-Stimulator Protein; Lymphocytic Choriomeningitis; Lymphocytic choriomeningitis virus; Mice; Programmed Cell Death 1 Receptor; T-Lymphocyte Subsets; T-Lymphocytes, Helper-Inducer
PubMed: 27501248
DOI: 10.1038/nature19330 -
Journal of Immunology (Baltimore, Md. :... Nov 2016The ability to culture and expand B cells in vitro has become a useful tool for studying human immunity. A limitation of current methods for human B cell culture is the...
The ability to culture and expand B cells in vitro has become a useful tool for studying human immunity. A limitation of current methods for human B cell culture is the capacity to support mature B cell proliferation. We developed a culture method to support the efficient activation and proliferation of naive and memory human B cells. This culture supports extensive B cell proliferation, with ∼10-fold increases following 8 d in culture and 10-fold increases when cultures are split and cultured for 8 more days. In culture, a significant fraction of naive B cells undergo isotype switching and differentiate into plasmacytes. Culture-derived (CD) B cells are readily cryopreserved and, when recovered, retain their ability to proliferate and differentiate. Significantly, proliferating CD B cells express high levels of MHC class II, CD80, and CD86. CD B cells act as APCs and present alloantigens and microbial Ags to T cells. We are able to activate and expand Ag-specific memory B cells; these cultured cells are highly effective in presenting Ag to T cells. We characterized the TCR repertoire of rare Ag-specific CD4 T cells that proliferated in response to tetanus toxoid (TT) presented by autologous CD B cells. TCR Vβ usage by TT-activated CD4 T cells differs from resting and unspecifically activated CD4 T cells. Moreover, we found that TT-specific TCR Vβ usage by CD4 T cells was substantially different between donors. This culture method provides a platform for studying the BCR and TCR repertoires within a single individual.
Topics: Antigen-Presenting Cells; B-Lymphocytes; CD4 Antigens; CD4-Positive T-Lymphocytes; Cell Culture Techniques; Cell Line; Cell Proliferation; Cells, Cultured; Humans; Immunologic Memory; Lymphocyte Activation; Receptors, Antigen, T-Cell; Tetanus Toxoid
PubMed: 27815447
DOI: 10.4049/jimmunol.1502193 -
Immunity Feb 2022T follicular helper (Tfh) cells are defined by a Bcl6CXCR5PD-1 phenotype, but only a minor fraction of these reside in germinal centers (GCs). Here, we examined whether...
T follicular helper (Tfh) cells are defined by a Bcl6CXCR5PD-1 phenotype, but only a minor fraction of these reside in germinal centers (GCs). Here, we examined whether GC-resident and -nonresident Tfh cells share a common physiology and function. Fluorescently labeled, GC-resident Tfh cells in different mouse models were distinguished by low expression of CD90. CD90 GCTfh cells required antigen-specific, MHCII B cells to develop and stopped proliferating soon after differentiation. In contrast, nonresident, CD90 Tfh (GCTfh-like) cells developed normally in the absence of MHCII B cells and proliferated continuously during primary responses. The TCR repertoires of both Tfh subsets overlapped initially but later diverged in association with dendritic cell-dependent proliferation of CD90 GCTfh-like cells, suggestive of TCR-dependency seen also in TCR-transgenic adoptive transfer experiments. Furthermore, the transcriptomes of CD90 and CD90 GCTfh-like cells were enriched in different functional pathways. Thus, GC-resident and nonresident Tfh cells have distinct developmental requirements and activities, implying distinct functions.
Topics: Animals; B-Lymphocytes; Cell Communication; Cell Differentiation; Cell Proliferation; Dendritic Cells; Gene Expression Profiling; Germinal Center; Histocompatibility Antigens Class II; Mice; Programmed Cell Death 1 Receptor; Receptors, Antigen, T-Cell; Receptors, CXCR5; Sphingosine-1-Phosphate Receptors; T Follicular Helper Cells; T-Lymphocyte Subsets; Thy-1 Antigens
PubMed: 35081372
DOI: 10.1016/j.immuni.2021.12.015 -
Veterinary Immunology and... May 2020CellTrace Violet™ is a commonly used fluorescent dye used with flow cytometry to identify cell proliferation. Activated equine lymphocytes were examined using flow...
CellTrace Violet™ is a commonly used fluorescent dye used with flow cytometry to identify cell proliferation. Activated equine lymphocytes were examined using flow cytometry, microscopy and tritiated thymidine proliferation assays. CellTrace Violet™ was incorporated into the equine lymphocytes effectively. Equine lymphocytes proliferated when activated with pokeweed mitogen, but did not proliferate when previously stained with CellTrace Violet™. Serial dilutions of CellTrace Violet™ did not eliminate the inhibition of activated lymphocytes. Equine lymphocyte viability was greater than 90 % for both stained and unstained cells. Based on these data, CellTrace Violet™ is not recommended for the assessment of lymphocyte proliferation in equine cells. The mechanism of inhibition of equine lymphocyte proliferation by CellTrace Violet™ is unknown.
Topics: Animals; Cell Proliferation; Cell Survival; Concanavalin A; Flow Cytometry; Fluorescent Dyes; Horses; Lymphocyte Activation; Lymphocytes; Pokeweed Mitogens
PubMed: 32229340
DOI: 10.1016/j.vetimm.2020.110037 -
Oncoimmunology Feb 2021The tumor microenvironment includes a complex network of cytokines and chemokines that contribute to shaping the intratumoral immune reaction. Understanding the... (Review)
Review
The tumor microenvironment includes a complex network of cytokines and chemokines that contribute to shaping the intratumoral immune reaction. Understanding the mechanisms leading to immune-hot (Immunoscore-high) altered (excluded and immunosuppressed) and cold tumors are of critical importance for successful anti-cancer therapies. Two essential mechanisms are highlighted. Specific chemokines and adhesion molecules appeared to target and attract immune effector T cells to the tumor microenvironment and to specific regions within the tumor. These mechanisms are dependent upon intratumoral IL-15 expression. Decreased IL15 expression also affected the local proliferation of B and T lymphocytes. A comprehensive analysis revealed a major contribution of IL15 in shaping the tumor immune contexture. Thus, an lymphocytic infiltration is mediated through chemokines and attraction inside or around the tumor microenvironment, and an IL15-mediated lymphocytic proliferation, which expand the local pool of intratumoral cytotoxic CD8 T-cells are key determinants of the immune contexture. Increased IL15 expression and local proliferation of T-cells were associated with decreased risk of tumor recurrence and prolonged survival of cancer patients. These data provide further mechanisms to prioritize research and help in designing better therapeutic interventions.
Topics: CD8-Positive T-Lymphocytes; Cell Proliferation; Humans; Interleukin-15; Lymphocyte Activation; T-Lymphocytes, Cytotoxic
PubMed: 33628626
DOI: 10.1080/2162402X.2021.1886726 -
PloS One Sep 2010Quantitative understanding of the kinetics of lymphocyte proliferation and death upon activation with an antigen is crucial for elucidating factors determining the... (Review)
Review
Quantitative understanding of the kinetics of lymphocyte proliferation and death upon activation with an antigen is crucial for elucidating factors determining the magnitude, duration and efficiency of the immune response. Recent advances in quantitative experimental techniques, in particular intracellular labeling and multi-channel flow cytometry, allow one to measure the population structure of proliferating and dying lymphocytes for several generations with high precision. These new experimental techniques require novel quantitative methods of analysis. We review several recent mathematical approaches used to describe and analyze cell proliferation data. Using a rigorous mathematical framework, we show that two commonly used models that are based on the theories of age-structured cell populations and of branching processes, are mathematically identical. We provide several simple analytical solutions for a model in which the distribution of inter-division times follows a gamma distribution and show that this model can fit both simulated and experimental data. We also show that the estimates of some critical kinetic parameters, such as the average inter-division time, obtained by fitting models to data may depend on the assumed distribution of inter-division times, highlighting the challenges in quantitative understanding of cell kinetics.
Topics: Animals; Cell Death; Cell Proliferation; Humans; Kinetics; Lymphocyte Activation; Lymphocytes; Mathematical Computing; Models, Biological
PubMed: 20941358
DOI: 10.1371/journal.pone.0012775 -
Molecular Immunology Dec 2015Upon antigen stimulation, small and quiescent naïve T cells undergo an approximately 24h growth phase followed by rapid proliferation. Depending on the nature of the... (Review)
Review
Upon antigen stimulation, small and quiescent naïve T cells undergo an approximately 24h growth phase followed by rapid proliferation. Depending on the nature of the antigen and cytokine milieu, these proliferating T cells differentiate into distinctive functional subgroups that are essential for appropriate immune defense and regulation. T cells undergo a characteristic metabolic rewiring that fulfills the dramatically increased bioenergetic and biosynthetic demands during the transition between resting, activation and differentiation. Beyond this, T cells are distributed throughout the body and are able to function in a wide range of physio-pathological environments, including some with a dramatic metabolic derangement. As such, T cells must quickly respond to and adapt to fluctuations in environmental nutrient levels. We consider such responsiveness and adaptation in terms of metabolic plasticity, that is, an evolutionarilly selected process which allows T cells to illicit robust immune functions in response to either a continuous or disrupted nutrient supply. In this review, we illustrate the relevant metabolic pathways in T cells and discuss the ability of T cells to change their metabolic substrates in response to changes in the environment.
Topics: Animals; Cell Differentiation; Humans; Lymphocyte Activation; T-Lymphocytes
PubMed: 26277274
DOI: 10.1016/j.molimm.2015.07.036 -
PloS One 2016This study investigated whether an acute session of high-intensity interval training (HIIT) is sufficient to alter lymphocyte function and redox status. Sixteen young... (Clinical Trial)
Clinical Trial
This study investigated whether an acute session of high-intensity interval training (HIIT) is sufficient to alter lymphocyte function and redox status. Sixteen young healthy men underwent a HIIT session on a cycloergometer, consisting of eight bouts of 1 min at 90-100% of peak power, with 75 seconds of active recovery at 30 W between bouts. Venous blood was collected before, immediately after, and 30 minutes after the HIIT session. In response to Staphylococcus aureus superantigen B (SEB) stimulation, lymphocyte proliferation decreased and the IL-2 concentration increased after the HIIT session. However, the HIIT session had no effect on lymphocyte proliferation or IL-2 response to phytohemagglutinin stimulation. The HIIT session also induced lymphocyte redox imbalance, characterized by an increase in the concentration of thiobarbituric acid reactive substances and a decrease in the activity of the antioxidant enzyme catalase. Lymphocyte viability was not affected by the HIIT session. The frequencies of CD25+ and CD69+ T helper and B lymphocytes in response to superantigen stimulation were lower after exercise, suggesting that superantigen-induced lymphocyte activation was reduced by HIIT. However, HIIT also led to a reduction in the frequency of CD4+ and CD19+ cells, so the frequencies of CD25+ and CD69+ cells within the CD4 and CD19 cell populations were not affected by HIIT. These data indicate that the reduced lymphocyte proliferation observed after HIIT is not due to reduced early lymphocyte activation by superantigen. Our findings show that an acute HIIT session promotes lymphocyte redox imbalance and reduces lymphocyte proliferation in response to superantigenic, but not to mitogenic stimulation. This observation cannot be explained by alteration of the early lymphocyte activation response to superantigen. The manner in which lymphocyte function modulation by an acute HIIT session can affect individual immunity and susceptibility to infection is important and requires further investigation.
Topics: Apoptosis; Biomarkers; Cell Proliferation; Cell Survival; Cytokines; Exercise; Gene Expression Regulation; Heart Rate; Humans; Lymphocytes; Male; Oxidation-Reduction; Young Adult
PubMed: 27096389
DOI: 10.1371/journal.pone.0153647 -
Molecular Immunology Dec 2015Upon encountering pathogens, T cells mount immune responses by proliferating, increasing cellular mass and differentiating. These cellular changes impose significant... (Review)
Review
Upon encountering pathogens, T cells mount immune responses by proliferating, increasing cellular mass and differentiating. These cellular changes impose significant energetic challenges on T cells. It was believed that TCR and cytokine-mediated signaling are dominant dictators of T cell-mediated immune responses. Recently, it was recognized that T cells utilize metabolic transporters and metabolic sensors that allow them to rapidly respond to nutrient-limiting inflammatory environments. Metabolic sensors allow T cells to find a balance between energy consumption (anabolic metabolism) and production (catabolic metabolism) in order to mount effective immune responses. Also, metabolic regulators interact with cytokine-dependent transcriptional regulators, suggesting a more integrative and advanced model of T cell activation and differentiation. In this review, we will discuss recent discoveries regarding the roles of metabolic regulators in effector and memory T cell development and their interaction with canonical transcription factors.
Topics: Animals; Cell Differentiation; Humans; Immunity, Cellular; Lymphocyte Activation; T-Lymphocytes
PubMed: 26277275
DOI: 10.1016/j.molimm.2015.07.027 -
Lipids in Health and Disease Dec 2016Palmitoleic acid (PA) is a n-7 monounsaturated fatty acid (MUFA) secreted by adipose tissue and related to decreased insulin resistance in peripheral tissues. Evidences...
BACKGROUND
Palmitoleic acid (PA) is a n-7 monounsaturated fatty acid (MUFA) secreted by adipose tissue and related to decreased insulin resistance in peripheral tissues. Evidences have been shown that PA also decreased proinflammatory cytokine expression in cultured macrophages. Although studies have shown that other fatty acids (FAs) modulate several lymphocyte functions, the specific effect of PA on these cells is unknown. The aim of the present study was to evaluate the possible influence of PA on activation and differentiation of human lymphocytes in comparison to oleic acid (OA).
METHODS
Human lymphocytes were isolated from peripheral blood of health men and cultured in the presence of growing concentrations of PA or OA (5 to 200 μM), for 24 h. After that, cells were collected and cytotoxicity evaluated by flow cytometry. Then, we analyzed proliferative capacity in lymphocytes treated with non toxic concentrations of PA and OA (25 and 50 μM, respectively), in the presence or absence of concanavalin A (ConA). The Th1/Th2/Th17 cytokine production was determined by the Cytometric Bead Array. CD28 and CD95 surface expression and T regulatory cell percentage were determined by flow cytometry.
RESULTS
We observed that PA is toxic to lymphocytes above 50 μM. PA promoted a decrease of lymphocyte proliferation stimulated by ConA in both concentrations. PA also decreased CD28 externalization and increased CD95. On the other hand, OA did not alter these parameters. In the same way, PA reduced IL6, IFN-gamma, TNF-alpha and IL17A production in both concentration and IL2 only at 50 μM (in the presence of ConA). OA promoted IFN-gamma reduction in both concentrations and an increase of IL-2, IL4 and IL10 at 25 μM. Both fatty acids decreased the percentage of T regulatory cells.
CONCLUSION
In conclusion, PA promoted a suppressive effect on lymphocyte proliferation characterized by a decrease of Th1 and Th17 response, and co-stimulatory molecule (CD28). However, OA increased lymphocyte proliferation through IL2 production and Th2 response. These results also show a more suppressive effect of PA on lymphocytes in comparison to OA.
Topics: Adult; Cell Proliferation; Cytokines; Fatty Acids, Monounsaturated; Flow Cytometry; Humans; Lymphocyte Activation; Lymphocytes; Male; Middle Aged; Young Adult
PubMed: 27964715
DOI: 10.1186/s12944-016-0385-2