Onchocerciasis Fingerprints in the Geriatric Population: Does Host Immunity Play a Role?

One of the most debilitating consequences of aging is the progressive decline in immune function, known as immunosenescence. This phenomenon is characterized by a shift in T-cell phenotypes, with a manifest decrease of naive T-cells—dealing with newly encountered antigens—and a concomitant accumulation of senescent and regulatory T-cells, leading to a greater risk of morbidity and mortality in older subjects. Additionally, with aging, several studies have unequivocally revealed an increase in the prevalence of onchocerciasis infection. Most lymphatic complications, skin and eye lesions due to onchocerciasis are more frequent among the elderly population. While the reasons for increased susceptibility to onchocerciasis with age are likely to be multi-factorial, age-associated immune dysfunction could play a key role in the onset and progression of the disease. On the other hand, there is a growing consensus that infection with onchocerciasis may evoke deleterious effects on the host’s immunity and exacerbate immune dysfunction. Indeed, Onchocerca volvulus has been reported to counteract the immune responses of the host through molecular mimicry by impairing T-cell activation and interfering with the processing of antigens. Moreover, reports indicate impaired cellular and humoral immune responses even to non-parasite antigens in onchocerciasis patients. This diminished protective response may intensify the immunosenescence outcomes, with a consequent vulnerability of those affected to additional diseases. Taken together, this review is aimed at contributing to a better understanding of the immunological and potential pathological mechanisms of onchocerciasis in the older population.

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A role for CD9 molecules in T cell activation.

Journal of Experimental Medicine ◽

10.1084/jem.184.2.753 ◽

1996 ◽

Vol 184 (2) ◽

pp. 753-758 ◽

Cited By ~ 63

Author(s):

X G Tai ◽

Y Yashiro ◽

R Abe ◽

K Toyooka ◽

C R Wood ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Immune Responses ◽

T Cell Activation ◽

Cell Activation ◽

Expression Cloning ◽

Wild Type ◽

Almost All ◽

Antigen Presenting ◽

Deficient Mice

Costimulation mediated by the CD28 molecule plays an important role in optimal activation of T cells. However, CD28-deficient mice can mount effective T cell-dependent immune responses, suggesting the existence of other costimulatory systems. In a search for other costimulatory molecules on T cells, we have developed a monoclonal antibody (mAb) that can costimulate T cells in the absence of antigen-presenting cells (APC). The molecule recognized by this mAb, 9D3, was found to be expressed on almost all mature T cells and to be a protein of approximately 24 kD molecular mass. By expression cloning, this molecule was identified as CD9, 9D3 (anti-CD9) synergized with suboptimal doses of anti-CD3 mAb in inducing proliferation by virgin T cells. Costimulation was induced by independent ligation of CD3 and CD9, suggesting that colocalization of these two molecules is not required for T cell activation. The costimulation by anti-CD9 was as potent as that by anti-CD28. Moreover, anti-CD9 costimulated in a CD28-independent way because anti-CD9 equally costimulated T cells from the CD28-deficient as well as wild-type mice. Thus, these results indicate that CD9 serves as a molecule on T cells that can deliver a potent CD28-independent costimulatory signal.

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Murine regulatory T cells differ from conventional T cells in resisting the CTLA-4 reversal of TCR stop-signal

Blood ◽

10.1182/blood-2012-04-421420 ◽

2012 ◽

Vol 120 (23) ◽

pp. 4560-4570 ◽

Cited By ~ 28

Author(s):

Yuning Lu ◽

Helga Schneider ◽

Christopher E. Rudd

Keyword(s):

T Cells ◽

T Cell ◽

Regulatory T Cells ◽

Immune Responses ◽

T Cell Activation ◽

Cell Activation ◽

Mechanistic Explanation ◽

Stop Signal ◽

Detectable Effect ◽

First Time

Abstract CTLA-4 inhibits T-cell activation and protects against the development of autoimmunity. We and others previously showed that the coreceptor can induce T-cell motility and shorten dwell times with dendritic cells (DCs). However, it has been unclear whether this property of CTLA-4 affects both conventional T cells (Tconvs) and regulatory T cells (Tregs). Here, we report that CTLA-4 had significantly more potent effects on the motility and contact times of Tconvs than Tregs. This was shown firstly by anti–CTLA-4 reversal of the anti-CD3 stop-signal on FoxP3-negative cells at concentrations that had no effect on FoxP3-positive Tregs. Secondly, the presence of CTLA-4 reduced the contact times of DO11.10 x CD4+CD25− Tconvs, but not DO11.10 x CD4+CD25+ Tregs, with OVA peptide presenting DCs in lymph nodes. Thirdly, blocking of CTLA-4 with anti–CTLA-4 Fab increased the contact times of Tconvs, but not Tregs with DCs. By contrast, the presence of CD28 in a comparison of Cd28−/− and Cd28+/+ DO11.10 T cells had no detectable effect on the contact times of either Tconvs or Tregs with DCs. Our findings identify for the first time a mechanistic explanation to account for CTLA-4–negative regulation of Tconv cells but not Tregs in immune responses.

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Vector Order Determines Protection against Pathogenic Simian Immunodeficiency Virus Infection in a Triple-Component Vaccine by Balancing CD4+ and CD8+ T-Cell Responses

Journal of Virology ◽

10.1128/jvi.01120-17 ◽

2017 ◽

Vol 91 (23) ◽

Cited By ~ 3

Author(s):

Ulrike Sauermann ◽

Antonia Radaelli ◽

Nicole Stolte-Leeb ◽

Katharina Raue ◽

Massimiliano Bissa ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Immune Responses ◽

T Cell Activation ◽

Cell Activation ◽

T Cell Responses ◽

Target Cells ◽

Aids Vaccine ◽

Cell Responses ◽

Antibody Titers

ABSTRACT An effective AIDS vaccine should elicit strong humoral and cellular immune responses while maintaining low levels of CD4+ T-cell activation to avoid the generation of target cells for viral infection. The present study investigated two prime-boost regimens, both starting vaccination with single-cycle immunodeficiency virus, followed by two mucosal boosts with either recombinant adenovirus (rAd) or fowlpox virus (rFWPV) expressing SIVmac239 or SIVmac251 gag/pol and env genes, respectively. Finally, vectors were switched and systemically administered to the reciprocal group of animals. Only mucosal rFWPV immunizations followed by systemic rAd boost significantly protected animals against a repeated low-dose intrarectal challenge with pathogenic SIVmac251, resulting in a vaccine efficacy (i.e., risk reduction per exposure) of 68%. Delayed viral acquisition was associated with higher levels of activated CD8+ T cells and Gag-specific gamma interferon (IFN-γ)-secreting CD8+ cells, low virus-specific CD4+ T-cell responses, and low Env antibody titers. In contrast, the systemic rFWPV boost induced strong virus-specific CD4+ T-cell activity. rAd and rFWPV also induced differential patterns of the innate immune responses, thereby possibly shaping the specific immunity. Plasma CXCL10 levels after final immunization correlated directly with virus-specific CD4+ T-cell responses and inversely with the number of exposures to infection. Also, the percentage of activated CD69+ CD8+ T cells correlated with the number of exposures to infection. Differential stimulation of the immune response likely provided the basis for the diverging levels of protection afforded by the vaccine regimen. IMPORTANCE A failed phase II AIDS vaccine trial led to the hypothesis that CD4+ T-cell activation can abrogate any potentially protective effects delivered by vaccination or promote acquisition of the virus because CD4+ T helper cells, required for an effective immune response, also represent the target cells for viral infection. We compared two vaccination protocols that elicited similar levels of Gag-specific immune responses in rhesus macaques. Only the animal group that had a low level of virus-specific CD4+ T cells in combination with high levels of activated CD8+ T cells was significantly protected from infection. Notably, protection was achieved despite the lack of appreciable Env antibody titers. Moreover, we show that both the vector and the route of immunization affected the level of CD4+ T-cell responses. Thus, mucosal immunization with FWPV-based vaccines should be considered a potent prime in prime-boost vaccination protocols.

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Molecular Transfer of Human CD40 and OX40 Ligands to Leukemic Human B-CLL Cells Extensively Expands Tumor-Reactive Cytotoxic T-Lymphocytes.

Blood ◽

10.1182/blood.v104.11.951.951 ◽

2004 ◽

Vol 104 (11) ◽

pp. 951-951

Author(s):

Ettore Biagi ◽

Giampietro Dotti ◽

Eric Yvon ◽

Raphael Rousseau ◽

Edward Lee ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Immune Responses ◽

T Cell Activation ◽

Cd8 T Cells ◽

Cell Activation ◽

Fold Increase ◽

Mean Value ◽

Lymphocytic Leukemia ◽

Molecular Transfer

Abstract CD40 ligand is an accessory signal for T-cell activation and can overcome T-cell anergy. The OX40-OX40 ligand pathway is involved in the subsequent expansion of memory T cells. We expressed both human CD40L and OX40L on B-Chronic Lymphocytic Leukemia (B-CLL) cells, by exploiting the phenomenon of molecular transfer from fibroblasts engineered to over-express both of these TNF-receptor superfamily members. We analyzed the effects of the modified B-CLL cells on the number, phenotype and cytotoxic function of autologous T cells in seven B-CLL patients. Transfer of CD40L and OX40L to B-CLL cells was observed in all patients (mean value from 1% pre to 76% post for CD40L; from 0.7% pre to 88% post for OX40L). Subsequent up-regulation of the costimulatory molecules CD80 (B7-1) and CD86 (B7-2) was obtained after engagement of the endogenous CD40 receptor on B-CLL by the transferred CD40L molecules (mean value from 8% pre to 64% post for CD80; from 36% pre to 95% post for CD86). Co-culture of modified and unmodified B-CLL cells with autologous T cells revealed profound differences in the immune responses they induced. With unmodified B-CLL cells, or cells expressing either CD40L or OX40L individually, less than a 10-fold expansion of autologous T cells was observed, with a <100-fold expansion in tumor reactive T cells (measured by IFN-gamma Elispot with autologous B-CLL cells as stimulators, and allogeneic B-CLL cells as controls). By contrast, co-culture with B-CLL cells expressing both CD40L and OX40L induced a >40 fold expansion of autologous T cells - including both CD8+ T cells and CD4+ T cells with a Th1 pattern of cytokine release - and a >2500-fold increase in leukemia-reactive T cells. These expanded T cells were also directly cytotoxic to B-CLL targets, producing a mean 48% B-CLL killing at an E:T ratio of 10:1. A proportion of these tumor-reactive CD8+ T cells were specific for survivin, a B-CLL associated tumor antigen. Hence the combination of CD40L and OX40L expression by B-CLL cells allows generation of potent immune responses to B-CLL, which may be exploitable either by using active immunization with CD40L/OX40L-modified tumor cells or by adoptive immunotherapy with CD40L/OX40L generated tumor-reactive T cells.

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Initiation of Autoimmune Diabetes by Developmentally Regulated Presentation of Islet Cell Antigens in the Pancreatic Lymph Nodes

Journal of Experimental Medicine ◽

10.1084/jem.189.2.331 ◽

1999 ◽

Vol 189 (2) ◽

pp. 331-339 ◽

Cited By ~ 311

Author(s):

Petter Höglund ◽

Justine Mintern ◽

Caroline Waltzinger ◽

William Heath ◽

Christophe Benoist ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Lymph Nodes ◽

Beta Cell ◽

T Cell Activation ◽

Cell Activation ◽

Molecular Mimicry ◽

Autoimmune Diabetes ◽

Activated T Cells ◽

Pancreatic Lymph Nodes

Little is known about the events triggering lymphocyte invasion of the pancreatic islets in prelude to autoimmune diabetes. For example, where islet-reactive T cells first encounter antigen has not been identified. We addressed this issue using BDC2.5 T cell receptor transgenic mice, which express a receptor recognizing a natural islet beta cell antigen. In BDC2.5 animals, activated T cells were found only in the islets and the lymph nodes draining them, and there was a close temporal correlation between lymph node T cell activation and islet infiltration. When naive BDC2.5 T cells were transferred into nontransgenic recipients, proliferating cells were observed only in pancreatic lymph nodes, and this occurred significantly before insulitis was detectable. Surprisingly, proliferation was not seen in 10-day-old recipients. This age-dependent dichotomy was reproduced in a second transfer system based on an unrelated antigen artificially expressed on beta cells. We conclude that beta cell antigens are transported specifically to pancreatic lymph nodes, where they trigger reactive T cells to invade the islets. Systemic or extrapancreatic T cell priming, indicative of activation via molecular mimicry or superantigens, was not seen. Compromised presentation of beta cell antigens in the pancreatic lymph nodes of juvenile animals may be the root of a first “checkpoint” in diabetes progression.

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The Microbiota Contributes to CD8+T Cell Activation and Nutrient Malabsorption following Intestinal Infection with Giardia duodenalis

Infection and Immunity ◽

10.1128/iai.00348-16 ◽

2016 ◽

Vol 84 (10) ◽

pp. 2853-2860 ◽

Cited By ~ 22

Author(s):

Aleksander Keselman ◽

Erqiu Li ◽

Jenny Maloney ◽

Steven M. Singer

Keyword(s):

T Cells ◽

T Cell ◽

Immune Responses ◽

Lamina Propria ◽

Antibiotic Treatment ◽

T Cell Activation ◽

Cell Activation ◽

Giardia Duodenalis ◽

Content Type ◽

Αβ T Cells

Giardia duodenalisis a noninvasive luminal pathogen that impairs digestive function in its host in part by reducing intestinal disaccharidase activity. This enzyme deficiency has been shown in mice to require CD8+T cells. We recently showed that both host immune responses and parasite strain affected disaccharidase levels during murine giardiasis. However, high doses of antibiotics were used to facilitate infections in that study, and we therefore decided to systematically examine the effects of antibiotic use on pathogenesis and immune responses in the mouse model of giardiasis. We found that antibiotic treatment did not overtly increase the parasite burden but significantly limited the disaccharidase deficiency observed in infected mice. Moreover, while infected mice had more activated CD8+αβ T cells in the small intestinal lamina propria, this increase was absent in antibiotic-treated mice. Infection also led to increased numbers of CD4+αβ T cells in the lamina propria and activation of T cell receptor γδ-expressing intraepithelial lymphocytes (IEL), but these changes were not affected by antibiotics. Finally, we show that activated CD8+T cells express gamma interferon (IFN-γ) and granzymes but that granzymes are not required for sucrase deficiency. We conclude that CD8+T cells become activated in giardiasis through an antibiotic-sensitive process and contribute to reduced sucrase activity. These are the first data directly demonstrating activation of CD8+T cells and γδ T cells duringGiardiainfections. These data also demonstrate that disruption of the intestinal microbiota by antibiotic treatment prevents pathological CD8+T cell activation in giardiasis.

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Induction of Antigen-Specific T-Cell Responses through Dendritic Cell Vaccination in AML: Results of a Phase I/II Trial and Ex Vivo Enhancement By Checkpoint Blockade

Blood ◽

10.1182/blood.v128.22.764.764 ◽

2016 ◽

Vol 128 (22) ◽

pp. 764-764 ◽

Cited By ~ 5

Author(s):

Felix S. Lichtenegger ◽

Katrin Deiser ◽

Maurine Rothe ◽

Frauke M. Schnorfeil ◽

Christina Krupka ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Immune Responses ◽

Phase I ◽

T Cell Activation ◽

Cell Activation ◽

Next Generation ◽

Cell Responses ◽

Ifn Γ

Abstract Postremission therapy is critical for successful elimination of minimal residual disease (MRD) in acute myeloid leukemia (AML). Innovative treatment options are needed for patients that are not eligible for allogeneic stem cell transplantation. As the intrinsic immune response against leukemia-associated antigens (LAAs) is generally low, the clinical application of checkpoint inhibitors as monotherapy is less promising in AML compared to other hemato-oncological diseases. Therapeutic vaccination with autologous dendritic cells (DCs) loaded with LAAs is a promising treatment strategy to induce anti-leukemic immune responses. We have conducted a phase I/II proof-of-concept study using monocyte-derived next-generation DCs as postremission therapy of AML patients with a non-favorable risk profile in CR/CRi after intensive induction therapy (NCT01734304). These DCs are generated using a GMP-compliant 3-day protocol including a TLR7/8 agonist, loaded with RNA encoding the LAAs WT1 and PRAME as well as CMVpp65 as adjuvant/surrogate antigen, and are applied intradermally up to 10 times within 26 weeks. The primary endpoint of the trial is feasibility and safety of the vaccination. Secondary endpoints are immunological responses and disease control. After the safety and toxicity profile was evaluated within phase I (n=6), the patient cohort was expanded to a total of 13 patients. DCs of sufficient number and quality could be generated from leukapheresis in 11/12 cases. DCs exhibited an immune-stimulatory profile based on high costimulatory molecule expression, IL-12p70 secretion, migration towards a chemokine gradient and processing and presentation of antigen. In 9/9 patients that are currently evaluable, we observed delayed-type hypersensitivity (DTH) responses at the vaccination site, but no grade III/IV toxicities. TCR repertoire analysis by next-generation sequencing revealed an enrichment of particular clonotypes at DTH sites. In the peripheral blood, we detected vaccination-specific T cell responses by multimer staining and by ELISPOT analysis: 7/7 patients showed responses to CMVpp65, including both boosting of pre-existing T cells in CMV+ patients and induction of a primary T cell response in CMV- patients. 2/7 patients exhibited responses to PRAME and WT each. 7/10 vaccinated patients are still alive, and 5/10 are in CR, with an observation period of up to 840 days. In vitro, DC-activated T cells showed an upregulation of PD-1 and LAG-3, while the DCs expressed the respective ligands PD-L1 and HLA-DR. Therefore, we studied the capacity of checkpoint blocking antibodies to further enhance T-cell activation by DCs. We found that blockade of PD-1 and particularly of LAG-3 was highly effective in enhancing both IFN-γ secretion and proliferation of T cells. Both pathways seem to target different T-cell subsets, as PD-1 blockade resulted in increased IFN-γ secretion by TN- and TEM-subsets, while blockade of LAG-3 significantly affected TN- and TCM-subsets. We conclude that vaccination with next-generation LAA-expressing DCs in AML is feasible, safe, and induces anti-leukemic immune responses in vivo. Our in vitro data supports the hypothesis that T-cell activation by means of the vaccine could be further enhanced by blocking PD-1 and/or LAG-3. Disclosures Subklewe: AMGEN Research Munich: Research Funding.

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Abstract 15489: Hematopoietic PI3-Kinase δ-Deficiency Exacerbates Lesional Macrophage Infiltration and Atherosclerosis in LDLR-/- Mice

Circulation ◽

10.1161/circ.130.suppl_2.15489 ◽

2014 ◽

Vol 130 (suppl_2) ◽

Author(s):

Mario Zierden ◽

Christopher Millarg ◽

Marius Vantler ◽

Eva Berghausen ◽

Stephan Baldus ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Immune Responses ◽

T Cell Activation ◽

Cell Activation ◽

Atherosclerotic Lesion ◽

Mononuclear Phagocytes ◽

Adaptive Immune ◽

Arterial Blood ◽

Paraaortic Lymph Nodes

Atherosclerosis and its consequences such as myocardial infarction and ischemic stroke remains the leading cause of death in western countries. Atherosclerosis is a chronic inflammatory disease of arterial blood vessels, critically involving macrophages, dendritic cells and T lymphocytes. Leukocytes highly express the catalytic phosphoinositide 3-kinase isoform p110δ (PI3Kδ), exerting a key role in the regulation of immune responses including activation, differentiation and effector function of lymphocytes. Therefore, PI3Kδ represents a promising target for the modulation of inflammatory processes during atherogenesis. To investigate the role of leukocytic PI3Kδ during atherogenesis, lethally irradiated LDLR -/- mice were either transplanted with bone marrow from PI3Kδ -/- or PI3Kδ +/+ mice. After recovery, recipient mice were fed an atherogenic diet for 6 weeks. Hypercholesterolemic PI3Kδ -/- recipient LDLR -/- mice displayed a profound reduction of peripheral B and T cells as well as strongly impaired CD4 + T-cell activation, T-helper 1 response and regulatory T-cell numbers in paraaortic lymph nodes and spleen compared with PI3Kδ +/+ transplanted controls. Surprisingly, the profound impairment of the adaptive immune system by PI3Kδ-deficiency caused a considerable aggravation of atherosclerosis in LDLR -/- mice. Atherosclerotic lesion area at the aortic root and abdominal aorta of PI3Kδ -/- recipient LDLR -/- mice was significantly increased by 72% and 218% compared with PI3Kδ +/+ recipients, respectively (n = 10[[Unable to Display Character: –]]20; P < 0.001). Importantly, atherosclerotic lesions of PI3Kδ-deficient LDLR -/- mice were characterized by a lower fraction of CD4 + T cells and a higher proportion of MOMA-2 + monocytes/macrophages compared with controls despite unaltered circulating monocyte subsets. Thus, PI3Kδ-deficiency in mononuclear phagocytes may contribute to enhanced plaque growth. In summary, we demonstrate that hematopoietic PI3Kδ plays a crucial role in regulating innate and adaptive immune responses within the arterial wall by exerting protective functions during atherogenesis. Current studies aim to dissect PI3Kδ-dependent mechanisms that modulate inflammatory and regulatory processes in multiple stages of atherosclerosis.

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Phase 1b study with PEGylated human IL-10 (AM0010) with 5-FU and oxaliplatin (FOLFOX) in metastatic pancreatic adenocarcinoma (PDAC).

Journal of Clinical Oncology ◽

10.1200/jco.2017.35.4_suppl.399 ◽

2017 ◽

Vol 35 (4_suppl) ◽

pp. 399-399 ◽

Cited By ~ 4

Author(s):

J. Randolph Hecht ◽

Aung Naing ◽

Gerald Falchook ◽

Manish R. Patel ◽

Jeffrey R. Infante ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Immune Responses ◽

T Cell Activation ◽

Cd8 T Cells ◽

Cell Activation ◽

De Novo ◽

Single Agent ◽

Hematological Toxicity ◽

Phase 1B

399 Background: The benefit of adding nal-irinotecan or oxaliplatin to 5-FU in second-line therapy for PDAC is relatively small and it has been refractory to immune therapies. The success and the durability of immunotherapy is thought to depend on the activation and expansion of intratumoral, tumor specific cytotoxic CD8+ T cells which are absent in most PDACs. AM0010 stimulates the survival, expansion and cytotoxicity of intratumoral CD8+ T cells. Immune stimulation and prolonged stable disease in PDAC patients (pts) with single agent AM0010 was recently presented. Irinotecan may eliminate cytotoxic T cells. Treatment with platinum or 5-FU may activate immune responses to cancer and AM0010 has synergistic anti-tumor function with both in preclinical models. In this phase 1b clinical study, the efficacy of AM0010 with FOLFOX was explored in patients with PDAC. Methods: PDAC pts progressing on a median of 1 prior therapy (range 1-3) were treated daily with AM0010 in combination with FOLFOX (n=20). Tumor responses were monitored using irRC. Immune responses were monitored using analysis of serum cytokines, activation of blood derived T cells and peripheral T cell clonality. Pretreatment samples were analyzed by IHC for tumor infiltration by CD8+ T cells. Results: G3/4 TrAEs included thrombocytopenia (55%), anemia (45%) and neutropenia (25%). There was no significant bleeding or febrile neutropenia. 16 pts had a objective tumor response assessment; 2 had an irCR, 1 an irPR, 10 had irSD. Eight remain on treatment, 2 for > 1 year. ORR was 15%, the DCR was 65%. The mPFS was 3.9 months. AM0010 increased serum Th1 cytokines and reduced mediators of chronic inflammation IL-23 and IL-17 and the immunosuppressive cytokine TGFb. AM0010 increased the number and proliferation of PD1+ activated CD8+ T cells and induced de-novo oligoclonal expansion of T cell clones without affecting total lymphocyte counts. Conclusions: AM0010 with FOLFOX is well tolerated with moderate hematological toxicity in patients with PDAC. The observed immune activation including CD8+ T cell activation and prolonged objective responses are encouraging and will be explored in a phase 3 trial starting in 2016.

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Hiding in Plain Sight: Virtually Unrecognizable Memory Phenotype CD8+ T cells

International Journal of Molecular Sciences ◽

10.3390/ijms21228626 ◽

2020 ◽

Vol 21 (22) ◽

pp. 8626

Author(s):

Daniel Thiele ◽

Nicole L. La Gruta ◽

Angela Nguyen ◽

Tabinda Hussain

Keyword(s):

T Cells ◽

T Cell ◽

T Cell Activation ◽

Cd8 T Cells ◽

Cell Activation ◽

Recent Literature ◽

Biological Significance ◽

Cell Lineage ◽

The Elderly ◽

Specific Response

Virtual memory T (TVM) cells are a recently described population of conventional CD8+ T cells that, in spite of their antigen inexperience, express markers of T cell activation. TVM cells exhibit rapid responsiveness to both antigen-specific and innate stimuli in youth but acquire intrinsic antigen-specific response defects in the elderly. In this article, we review how the identification of TVM cells necessitates a re-evaluation of accepted paradigms for conventional memory T (TMEM) cells, the potential for heterogeneity within the TVM population, and the defining characteristics of TVM cells. Further, we highlight recent literature documenting the development of TVM cells as a distinct CD8+ T cell lineage as well their biological significance in the context of disease.

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