Values for αβ and γδ T-lymphocytes and CD4+, CD8+, and CD56+ subsets in healthy adult subjects: assessment by age and gender

Immune profiling of age and adjuvant-specific activation of human blood mononuclear cells in vitro

Vaccination reduces morbidity and mortality due to infections, but efficacy may be limited due to distinct immunogenicity at the extremes of age. This raises the possibility of employing adjuvants to enhance immunogenicity and protection. Early IFNγ production is a hallmark of effective vaccine immunogenicity in adults serving as a biomarker that may predict effective adjuvanticity. We utilized mass cytometry (CyTOF) to dissect the source of adjuvant-induced cytokine production in human blood mononuclear cells (BMCs) from newborns (~39-week-gestation), adults (~18-63 years old) and elders (>65 years of age) after stimulation with pattern recognition receptors agonist (PRRa) adjuvants. Dimensionality reduction analysis of CyTOF data mapped the BMC compartment, elucidated age-specific immune responses and profiled PRR-mediated activation of monocytes and DCs upon adjuvant stimulation. Furthermore, we demonstrated PRRa adjuvants mediated innate IFNγ induction and mapped NK cells as the key source of TLR7/8 agonist (TLR7/8a) specific innate IFNγ responses. Hierarchical clustering analysis revealed age and TLR7/8a-specific accumulation of innate IFNγ producing γδ T cells. Our study demonstrates the application of mass cytometry and cutting-edge computational approaches to characterize immune responses across immunologically distinct age groups and may inform identification of the bespoke adjuvantation systems tailored to enhance immunity in distinct vulnerable populations.

Patients with systemic sclerosis and low CD4 numbers after autologous stem cell transplantation have a favorable outcome

BACKGROUND

Treatment with high-dose chemotherapy followed by autologous hematopoietic stem cell transplantation (aHSCT) is an intensive treatment option for patients with severe forms of systemic sclerosis (SSc). Even though associated with a high treatment related mortality, the results in this high-risk population are generally favourable. The knowledge on the potential mechanism of action of this therapy and how it can improve patients with SSc is crucial to better select the right patients for aHSCT.

METHODS

This is a monocentric retrospective study from Tübingen, Germany, including 32 patients who underwent aHSCT. Peripheral blood samples were analysed for different lymphocyte subsets at various timepoints before and after aHSCT. Patients were divided into responders and non-responders according to the modified Rodnan skin score and lung function test in the three years following aHSCT.

RESULTS

Responders showed significantly lower levels of cluster of differentiation (CD)4 positive T cells in the first months after aHSCT (month 1 and 3), B cells (month 3 and 6 after aHSCT) and natural killer cells (month 1). Mantel-cox test showed a significant deviation of the probability curves, i.e. patients with lower CD4 + T cells and natural killer cells one month and B cells after 3 months after stem cell transplantation had a higher probability to belong to the responder group.

CONCLUSIONS

Taken together, this study supports the theory that a profound CD4 + T cell and B cell lymphopenia is important for patients with SSc to achieve a sustained response after aHSCT.

Hyperactivation and enhanced cytotoxicity of reduced CD8+ gamma delta T cells in the intestine of patients with Crohn's disease correlates with disease activity

BACKGROUND AND AIMS

We aimed to investigate the immune characteristics of intestinal CD8+ gamma delta T (CD8+ γδ T) cells in Crohn's disease (CD) and their correlation with disease activity.

METHODS

The study cohorts included 21 CD patients and 21 healthy individuals. CD8+ γδ T cells were isolated from human ileal mucosa for detection by flow cytometry. The activation or inhibition status of cells was detected by detecting the expression of activation marker HLA-DR and the immunosuppressive molecule PD-1 on cells. The cytotoxicity of cells was assessed by detecting the expression of cytotoxic molecules (Perforin, Granzyme B, and TRAIL) in cells. Ratios of investigated cells were calculated as prediction factors by receiver operating characteristic curve (ROC) analysis.

RESULTS

The study revealed a reduction in intestinal CD8+ γδT cells among active CD patients, with a more pronounced reduction observed in moderately active patients compared to mildly active patients. Moreover, active CD patients exhibited heightened activation levels in their intestinal CD8+ γδT cells, whereas the activation was comparatively weakened in moderately active patients compared with mildly active patients. Additionally, the cytotoxicity of intestinal CD8+ γδT cells was enhanced solely in mildly active patients, while it was impaired in moderately active patients compared with mildly active patients. Furthermore, HLA-DR+ CD8+ γδT cell ratio, CD8+ γδT ratio, and CD8+ γδT count were identified as indicators in the diagnosis of active CD. Meanwhile, the ratios of Granzyme B+ CD8+ γδT cell and Perforin+ CD8+ γδT cell were identified as indicators that distinguish mildly moderately active CD cases.

CONCLUSIONS

Intestinal CD8+ γδT was reduced in active CD patients, but their activation and cytotoxicity were enhanced. However, with increased disease activity, intestinal CD8+ γδ T cells became dysfunctional. CD-specific perturbations observed in various phenotypic markers in CD8+ γδ T cells can be used as indicators to assist in diagnosing CD patients.

Immunology of cord blood T-cells favors augmented disease response during clinical pediatric stem cell transplantation for acute leukemia

Allogeneic hematopoietic stem cell transplantation (HSCT) has been an important and efficacious treatment for acute leukemia in children for over 60 years. It works primarily through the graft-vs.-leukemia (GVL) effect, in which donor T-cells and other immune cells act to eliminate residual leukemia. Cord blood is an alternative source of stem cells for transplantation, with distinct biological and immunological characteristics. Retrospective clinical studies report superior relapse rates with cord blood transplantation (CBT), when compared to other stem cell sources, particularly for patients with high-risk leukemia. Xenograft models also support the superiority of cord blood T-cells in eradicating malignancy, when compared to those derived from peripheral blood. Conversely, CBT has historically been associated with an increased risk of transplant-related mortality (TRM) and morbidity, particularly from infection. Here we discuss clinical aspects of CBT, the unique immunology of cord blood T-cells, their role in the GVL effect and future methods to maximize their utility in cellular therapies for leukemia, honing and harnessing their antitumor properties whilst managing the risks of TRM.

Assessment of immune cell profiles among post-menopausal women in the Women's Health Initiative using DNA methylation-based methods

BACKGROUND

Over the past decade, DNA methylation (DNAm)-based deconvolution methods that leverage cell-specific DNAm markers of immune cell types have been developed to provide accurate estimates of the proportions of leukocytes in peripheral blood. Immune cell phenotyping using DNAm markers, termed immunomethylomics or methylation cytometry, offers a solution for determining the body's immune cell landscape that does not require fresh blood and is scalable to large sample sizes. Despite significant advances in DNAm-based deconvolution, references at the population level are needed for clinical and research interpretation of these additional immune layers. Here we aim to provide some references for immune populations in a group of multi-ethnic post-menopausal American women.

RESULTS

We applied DNAm-based deconvolution to a large sample of post-menopausal women enrolled in the Women's Health Initiative (baseline, N = 58) or the ancillary Long Life Study (WHI-LLS, N = 1237) to determine the reference ranges of 58 immune parameters, including proportions and absolute counts for 19 leukocyte subsets and 20 derived cell ratios. Participants were 50-94 years old at the time of blood draw, and N = 898 (69.3%) self-identified as White. Using linear regression models, we observed significant associations between age at blood draw and absolute counts and proportions of naïve B, memory CD4+, naïve CD4+, naïve CD8+, memory CD8+ memory, neutrophils, and natural killer cells. We also assessed the same immune profiles in a subset of paired longitudinal samples collected 14-18 years apart across N = 52 participants. Our results demonstrate high inter-individual variability in rates of change of leukocyte subsets over this time. And, when conducting paired t tests to test the difference in counts and proportions between the baseline visit and LLS visit, there were significant changes in naïve B, memory CD4+, naïve CD4+, naïve CD8+, memory CD8+ cells and neutrophils, similar to the results seen when analyzing the association with age in the entire cohort.

CONCLUSIONS

Here, we show that derived cell counts largely reflect the immune profile associated with proportions and that these novel methods replicate the known immune profiles associated with age. Further, we demonstrate the value this methylation cytometry approach can add as a potential application in epidemiological studies.

Development of a standardized and validated flow cytometry approach for monitoring of innate myeloid immune cells in human blood

Innate myeloid cell (IMC) populations form an essential part of innate immunity. Flow cytometric (FCM) monitoring of IMCs in peripheral blood (PB) has great clinical potential for disease monitoring due to their role in maintenance of tissue homeostasis and ability to sense micro-environmental changes, such as inflammatory processes and tissue damage. However, the lack of standardized and validated approaches has hampered broad clinical implementation. For accurate identification and separation of IMC populations, 62 antibodies against 44 different proteins were evaluated. In multiple rounds of EuroFlow-based design-testing-evaluation-redesign, finally 16 antibodies were selected for their non-redundancy and separation power. Accordingly, two antibody combinations were designed for fast, sensitive, and reproducible FCM monitoring of IMC populations in PB in clinical settings (11-color; 13 antibodies) and translational research (14-color; 16 antibodies). Performance of pre-analytical and analytical variables among different instruments, together with optimized post-analytical data analysis and reference values were assessed. Overall, 265 blood samples were used for design and validation of the antibody combinations and in vitro functional assays, as well as for assessing the impact of sample preparation procedures and conditions. The two (11- and 14-color) antibody combinations allowed for robust and sensitive detection of 19 and 23 IMC populations, respectively. Highly reproducible identification and enumeration of IMC populations was achieved, independently of anticoagulant, type of FCM instrument and center, particularly when database/software-guided automated (vs. manual “expert-based”) gating was used. Whereas no significant changes were observed in identification of IMC populations for up to 24h delayed sample processing, a significant impact was observed in their absolute counts after >12h delay. Therefore, accurate identification and quantitation of IMC populations requires sample processing on the same day. Significantly different counts were observed in PB for multiple IMC populations according to age and sex. Consequently, PB samples from 116 healthy donors (8-69 years) were used for collecting age and sex related reference values for all IMC populations. In summary, the two antibody combinations and FCM approach allow for rapid, standardized, automated and reproducible identification of 19 and 23 IMC populations in PB, suited for monitoring of innate immune responses in clinical and translational research settings.

Changes of CD3+CD56+ γδ T cell number and apoptosis during hospital admission are related to mortality in septic patients

Immunoparalysis and apoptosis of T cells are serious problems for the evolution of septic patients. We aimed to relate changes in the number of αβ and γδ T cells during hospital stay to the poor evolution of sepsis. In this prospective study, we recruited a total of 92 septic patients from the Emergency and Intensive Care Departments of two Hospitals, according to the latest criteria for the definition and management of sepsis. According to the severity of the septic process, there was a progressive decrease in T cells, being much more intense in γδ T cells. This decrease recovered in surviving patients, but CD3+CD56+ γδ T cells continued to decreased during hospital stay in non-surviving patients. Apoptosis increased in sepsis. Cell death of CD3+CD56+ γδ T cells progressively increased according to the severity of sepsis, especially in non-surviving patients.

The Mysterious Actor-γδ T Lymphocytes in Chronic Lymphocytic Leukaemia (CLL)

Chronic lymphocytic leukaemia (CLL) is the most common leukaemia among adults. It is the clonal expansion of B cells expressing CD19 and CD5. Despite significant progress in treatment, CLL is still incurable. γδ T cells comprise an important subset of the cytotoxic T cells. Although γδ T cells in CLL are dysfunctional, they still can possibly be used for immunotherapy. The current paper reviews our understanding of γδ T lymphocytes in CLL.

Age-dependent frequency of unconventional T cells in a healthy adult Caucasian population: a combinational study of invariant natural killer T cells, γδ T cells, and mucosa-associated invariant T cells

Unconventional T cells show distinct and unique features during antigen recognition as well as other immune responses. Their decrease in frequency is associated with various autoimmune disorders, allergy, inflammation, and cancer. The landscape frequency of the unconventional T cells altogether (iNKT, γδ T, and MAIT) is largely unestablished leading to various challenges affecting diagnosis and research in this field. In this study, we have established the age group–wise frequency of iNKT, γδ T, and MAIT cells altogether on a total of 203 healthy adult samples of the Caucasian population. The results revealed that iNKT cells were 0.095%, γδ T cells were 2.175%, and MAIT cells were 2.99% of the total T cell population. γδ and MAIT cell frequency is higher in younger age groups than elderly; however, there is no statistically significant difference in the frequency of iNKT cells. Furthermore, γδ and MAIT cells were negatively correlating with age, supporting immunosenescence, unlike iNKT cells. Our finding could be used for further age-wise investigation of various pathological conditions such as cancer and their prognosis, autoimmune diseases and their pathogenicity.

Potentiating Vγ9Vδ2 T cell proliferation and assessing their cytotoxicity towards adherent cancer cells at the single cell level

Vγ9Vδ2 T cells is the dominant γδ T cell subset in human blood. They are cytotoxic and activated by phosphoantigens whose concentrations are increased in cancer cells, making the cancer cells targets for Vγ9Vδ2 T cell immunotherapy. For successful immunotherapy, it is important both to characterise Vγ9Vδ2 T cell proliferation and optimise the assessment of their cytotoxic potential, which is the aim of this study. We found that supplementation with freshly-thawed human serum potentiated Vγ9Vδ2 T cell proliferation from peripheral mononuclear cells (PBMCs) stimulated with (E)-4-Hydroxy-3-methyl-but-2-enyl diphosphate (HMBPP) and consistently enabled Vγ9Vδ2 T cell proliferation from cryopreserved PBMCs. In cryopreserved PBMCs the proliferation was higher than in freshly prepared PBMCs. In a panel of short-chain prenyl alcohols, monophosphates and diphosphates, most diphosphates and also dimethylallyl monophosphate stimulated Vγ9Vδ2 T cell proliferation. We developed a method where the cytotoxicity of Vγ9Vδ2 T cells towards adherent cells is assessed at the single cell level using flow cytometry, which gives more clear-cut results than the traditional bulk release assays. Moreover, we found that HMBPP enhances the Vγ9Vδ2 T cell cytotoxicity towards colon cancer cells. In summary we have developed an easily interpretable method to assess the cytotoxicity of Vγ9Vδ2 T cells towards adherent cells, found that Vγ9Vδ2 T cell proliferation can be potentiated media-supplementation and how misclassification of non-responders may be avoided. Our findings will be useful in the further development of Vγ9Vδ2 T cell immunotherapy.

Alterations of circulating lymphocyte subsets in patients with colorectal carcinoma

Introduction

Cellular immune response to cancer is known to be of great importance for tumor control. Moreover, solid tumors influence circulating lymphocytes, which has been shown for several types of cancer. In our prospective study we elucidate changes in lymphocyte subsets in patients with colorectal carcinoma compared to healthy volunteers.

Methods

Flow cytometry was performed at diagnosis of colon carcinoma to analyze B cells, T cells and NK cells including various subtypes of each group. Univariate and multivariate analyses including age, gender, tumor stage, sidedness and microsatellite instability status (MSI) were performed.

Results

Forty-seven patients and 50 healthy volunteers were included. Median age was 65 years in patients and 43 years in the control group. Univariate analysis revealed lower total lymphocyte counts, lower CD4 + cells, CD8 + cells, B cells and NKs including various of their subsets in patients. In multivariate analysis patients had inferior values of B cells, CD4 + cells and NK cells and various subsets, regardless of age and gender. Naïve, central memory and HLADR + CD8 + cells showed an increase in patients whereas all other altered subsets declined. MSI status had no influence on circulating lymphocytes except for higher effector memory CD8 + cells in MSI-high patients. Localization in the left hemicolon led to higher values of total cytotoxic T cells and various T cell subsets.

Conclusion

We found significant changes in circulating lymphocyte subsets in colon carcinoma patients, independent of physiological alterations due to gender or age. For some lymphocyte subsets significant differences according to tumor localization or MSI-status could be seen.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00262-021-03127-8.

Impact of age and gender on lymphocyte subset counts in patients with COVID-19

In symptomatic patients with acute Coronavirus disease 2019 (COVID-19), lymphocytopenia is one of the most prominent laboratory findings. However, to date age and gender have not been considered in assessment of COVID-19-related cell count alterations. In this study, the impact of COVID-19 as well as age and gender on a large variety of lymphocyte subsets was analyzed in 33 COVID-19 patients and compared with cell counts in 50 healthy humans. We confirm that cell counts of total lymphocytes, B, NK, cytotoxic and helper T cells are reduced in patients with severe COVID-19, and this tendency was observed in patients with moderate COVID-19. Decreased cell counts were also found in all subsets of these cell types, except for CD4+ and CD8+ effector memory RA+ (EMRA) and terminal effector CD8+ cells. In multivariate analysis however, we show that in addition to COVID-19, there is an age-dependent reduction of total, central memory (CM), and early CD8+ cell subsets, as well as naïve, CM, and regulatory CD4+ cell subsets. Remarkably, reduced naïve CD8+ cell counts could be attributed to age alone, and not to COVID-19. By contrast, decreases in other subsets could be largely attributed to COVID-19, and only partly to age. In addition to COVID-19, male gender was a major factor influencing lower counts of CD3+ and CD4+ lymphocyte numbers. Our study confirms that cell counts of lymphocytes and their subsets are reduced in patients with COVID-19, but that age and gender must be considered when interpreting the altered cell counts.

The Role of Gamma-Delta T Cells in Diseases of the Central Nervous System

Gamma-delta (γδ) T cells are a subset of T cells that promote the inflammatory responses of lymphoid and myeloid lineages, and are especially vital to the initial inflammatory and immune responses. Given the capability to connect crux inflammations of adaptive and innate immunity, γδ T cells are responsive to multiple molecular cues and can acquire the capacity to induce various cytokines, such as GM-CSF, IL-4, IL-17, IL-21, IL-22, and IFN-γ. Nevertheless, the exact mechanisms responsible for γδ T cell proinflammatory functions remain poorly understood, particularly in the context of the central nervous system (CNS) diseases. CNS disease, usually leading to irreversible cognitive and physical disability, is becoming a worldwide public health problem. Here, we offer a review of the neuro-inflammatory and immune functions of γδ T cells, intending to understand their roles in CNS diseases, which may be crucial for the development of novel clinical applications.

Understanding human γδ T cell biology toward a better management of cytomegalovirus infection

Cytomegalovirus (CMV) infection is responsible for significant morbidity and mortality in immunocompromised patients, namely solid organ and hematopoietic cell transplant recipients, and can induce congenital infection in neonates. There is currently an unmet need for new management and treatment strategies. Establishment of an anti-CMV immune response is critical in order to control CMV infection. The two main human T cells involved in HCMV-specific response are αβ and non-Vγ9Vδ2 T cells that belong to γδ T cell compartment. CMV-induced non-Vγ9Vδ2 T cells harbor a specific clonal expansion and a phenotypic signature, and display effector functions against CMV. So far, only two main molecular mechanisms underlying CMV sensing have been identified. Non-Vγ9Vδ2 T cells can be activated either by stress-induced surface expression of the γδT cell receptor (TCR) ligand annexin A2, or by a multimolecular stress signature composed of the γδTCR ligand endothelial protein C receptor and co-stimulatory signals such as the ICAM-1-LFA-1 axis. All this basic knowledge can be harnessed to improve the clinical management of CMV infection in at-risk patients. In particular, non-Vγ9Vδ2 T cell monitoring could help better stratify the risk of infection and move forward a personalized medicine. Moreover, recent advances in cell therapy protocols open the way for a non-Vγ9Vδ2 T cell therapy in immunocompromised patients.

Gammadelta T cells as a predictor of surgical relapse of Crohn's disease

BACKGROUND

We recently demonstrated a decrease in the overall lymphocyte population in the peripheral blood of patients with CD compared to healthy controls and this decrease is more evident in γδ T lymphocytes. The percentages of T cell subsets could reflect the risk of surgical relapse in CD patients. The aim of this study is to study the correlation between αβ and γδ T cell subsets in the peripheral blood of patients with CD and the risk for surgery during follow up.

METHODS

A prospective study of 102 patients with CD compared with 102 healthy subjects (control group) matched by age and sex was conducted. Lymphocytic populations of CD3+, CD4+, CD8+, CD56+, and αβ and γδ T cell subsets were measured in the peripheral blood of all participants.

RESULTS

We found evidence of a relationship between lower γδ T cell levels and risk of surgical relapse in CD. The lowest subsets observed in CD patients with surgical relapse were CD3+γδ, CD3+CD8+γδ and CD3+CD56+γδT cells. We observed a relationship between a decrease in γδ T cells and the most severe forms of the disease. The lowest levels of CD3+γδ and CD3+CD8+γδT cells were observed in the fistulizing phenotype.

CONCLUSIONS

The deficit of γδ T cells was related with the severity and the risk for surgical relapse in CD patients. Patients with CD3+γδ deficit were more prone to surgery than patients without this deficit. These results suggest that γδ T cells could be used as markers of poor prognosis of CD following the diagnosis of the disease.

Flow cytometric evaluation of peripheral blood for suspected Sézary syndrome or mycosis fungoides: International guidelines for assay characteristics

A peripheral blood flow cytometric assay for Sézary syndrome (SS) or circulating mycosis fungoides (MF) cells must be able to reliably identify, characterize, and enumerate T-cells with an immunophenotype that differs from non-neoplastic T-cells. Although it is also important to distinguish SS and MF from other subtypes of T-cell neoplasm, this usually requires information in addition to the immunophenotype, such as clinical and morphologic features. This article outlines the approach recommended by an international group with experience and expertise in this area. The following key points are discussed: (a) At a minimum, a flow cytometric assay for SS and MF should include the following six antibodies: CD3, CD4, CD7, CD8, CD26, and CD45. (b) An analysis template must reliably detect abnormal T-cells, even when they lack staining for CD3 or CD45, or demonstrate a phenotype that is not characteristic of normal T-cells. (c) Gating strategies to identify abnormal T-cells should be based on the identification of subsets with distinctly homogenous immunophenotypic properties that are different from those expected for normal T-cells. (d) The blood concentration of abnormal cells, based on any immunophenotypic abnormalities indicative of MF or SS, should be calculated by either direct enumeration or a dual-platform method, and reported.

Characterization of human peripheral blood γδ T cells in patients with sepsis

In total, 30 cases of patients undergoing health check-ups with the diagnostic criteria of sepsis were included in the present study. The clinical data of each patient with sepsis were recorded at admission. In the present study, the association between the proportion of T cells in patients with sepsis and those in a healthy condition were observed. The expression of immunosuppressive molecules on the surface of Vδ1 T cells were examined, as well as studying the secretion of inflammatory cytokines in Vδ2 T cells, and the ability of the Vδ1 T cells to inhibit the secretory level of interferon-γ (IFN-γ) and the inflammatory function of Vδ2 T cells were monitored. The inhibition of proliferation of naïve CD4 T cells by Vδ1 T cells and inflammatory function of Vδ2 T cells were examined. The number of Vδ1 T cells in the peripheral blood of patients with sepsis was significantly increased compared with healthy controls (P<0.01); the proportion of Vδ2 T cells was opposite to that of Vδ1 T cells. The Sequential Organ Failure Assessment score, survival and survival time were positively associated with Vδ1 T cell ratio (P<0.05) and negatively correlated with Vδ2 T cells. The expression of cytotoxic T-lymphocyte protein 4 and T cell immunoglobulin and mucin domain-containing protein 3 on the surface of Vδ1 T cells in the peripheral blood of patients with sepsis was significantly increased compared with the healthy controls (P<0.01), and the levels of IFN-γ and tumor necrosis factor-α secreted by Vδ2 T cells were significantly decreased (P<0.01). The immunosuppressive function of Vδ1 T cells was significantly higher, and the function of Vδ2 T cells was significantly reduced (P<0.01). The phosphorylation level of Erk1/2 in Vδ2 T cells was significantly lower (P<0.01). The present results suggested that the imbalance and functional changes of different γδ T cell subtypes in the peripheral blood of patients with sepsis are associated with sepsis, and may be involved in sepsis progression.

Human Peripheral Blood Gamma Delta T Cells: Report on a Series of Healthy Caucasian Portuguese Adults and Comprehensive Review of the Literature

Gamma delta T cells (Tc) are divided according to the type of Vδ and Vγ chains they express, with two major γδ Tc subsets being recognized in humans: Vδ2Vγ9 and Vδ1. Despite many studies in pathological conditions, only a few have quantified the γδ Tc subsets in healthy adults, and a comprehensive review of the factors influencing its representation in the blood is missing. Here we quantified the total γδ Tc and the Vδ2/Vγ9 and Vδ1 Tc subsets in the blood from 30 healthy, Caucasian, Portuguese adults, we characterized their immunophenotype by 8-color flow cytometry, focusing in a few relevant Tc markers (CD3/TCR-γδ, CD5, CD8), and costimulatory (CD28), cytotoxic (CD16) and adhesion (CD56) molecules, and we examined the impacts of age and gender. Additionally, we reviewed the literature on the influences of race/ethnicity, age, gender, special periods of life, past infections, diet, medications and concomitant diseases on γδ Tc and their subsets. Given the multitude of factors influencing the γδ Tc repertoire and immunophenotype and the high variation observed, caution should be taken in interpreting “abnormal” γδ Tc values and repertoire deviations, and the clinical significance of small populations of “phenotypically abnormal” γδ Tc in the blood.

Occupational exposure to formaldehyde and early biomarkers of cancer risk, immunotoxicity and susceptibility

Formaldehyde (FA) is a high-volume production chemical manufactured worldwide to which many people are exposed to both environmentally and occupationally. FA was recently reclassified as a human carcinogen. Several epidemiological studies have revealed an increased risk of cancer development among workers exposed to FA. Although FA genotoxicity was confirmed in a variety of experimental systems, data from human studies are conflicting. The aim of the present study was to evaluate the occupational exposure to FA in a multistage approach relating the exposure with different biomarkers (dose and effect) and individual susceptibility. Air monitoring was performed to estimate the level of exposure to FA during shift work. Eighty-five workers from hospital anatomy-pathology laboratories exposed to FA and 87 controls were tested for cytogenetic alterations in lymphocytes (micronucleus, MN; sister-chromatid exchange, SCE) and T-cell receptor (TCR) mutation assay. The frequency of MN in exfoliated buccal cells, a first contact tissue was also assessed. Percentages of different lymphocyte subpopulations were selected as immunotoxicity biomarkers. The level of formic acid in urine was investigated as a potential biomarker of internal dose. The effects of polymorphic genes of xenobiotic metabolising enzymes and DNA repair enzymes on the endpoints studied were determined. The mean level of FA exposure was 0.38 ± 0.03 ppm. MN (in lymphocytes and buccal cells) and SCE were significantly increased in FA-exposed workers compared to controls. MN frequency positively correlated with FA levels of exposure and duration. Significant alterations in the percentage of T cytotoxic lymphocytes, NK cells and B lymphocytes were found between groups. Polymorphisms in CYP2E1, GSTP1 and FANCA genes were associated with increased genetic damage in FA-exposed subjects. The obtained information may provide new important data to be used by health and safety care programs and by governmental agencies responsible for setting the acceptable levels for occupational exposure to FA.

Age related human T cell subset evolution and senescence

T cells are fundamental effector cells against viruses and cancers that can be divided into different subsets based on their long-term immune protection and immediate immune response effects. The percentage and absolute number of these subsets change with ageing, which leads to a reduced immune response in older individuals. Stem cell memory T cells (T_SCM) represent a small population of memory T cells with enhanced proliferation and differentiation properties that are endowed with high potential for maintaining T cell homeostasis. However, whether these cells change with ageing and gender remains unknown. Here, we assayed the distribution of T_SCM and other T cell subsets in peripheral blood from 92 healthy subjects (44 females and 48 males) ranging from 3 to 88 years old by flow cytometry. We found that CD4+ and CD8+ T_SCM in the circulation have relatively stable frequencies, and the absolute number of CD8+ T_SCM decreased with age; however, the ratio of T_SCM to the CD4+ or CD8+ naïve population increased with age. Unlike the obvious changes in other T cell subsets with age and gender, the stable level of T_SCM in peripheral blood may support their capacity for sustaining long-term immunological memory, while their importance may increase together with ageing.

Peripheral PD-1+CD56+ T-cell frequencies correlate with outcome in stage IV melanoma under PD-1 blockade

Immune checkpoint blockade with anti-PD-1 antibodies is showing great promise for patients with metastatic melanoma and other malignancies, but despite good responses by some patients who achieve partial or complete regression, many others still do not respond. Here, we sought peripheral blood T-cell biomarker candidates predicting treatment outcome in 75 stage IV melanoma patients treated with anti-PD-1 antibodies. We investigated associations with clinical response, progression-free survival (PFS) and overall survival (OS). Univariate analysis of potential biological confounders and known biomarkers, and a multivariate model, was used to determine statistical independence of associations between candidate biomarkers and clinical outcomes. We found that a lower than median frequency of peripheral PD-1+CD56+ T-cells was associated with longer OS (p = 0.004), PFS (p = 0.041) and superior clinical benefit (p = 0.009). However, neither frequencies of CD56-CD4+ nor CD56-CD8+ T-cells, nor of the PD-1+ fraction within the CD4 or CD8 subsets was associated with clinical outcome. In a multivariate model with known confounders and biomarkers only the M-category (HR, 3.11; p = 0.007) and the frequency of PD-1+CD56+ T-cells (HR, 2.39; p = 0.028) were identified as independent predictive factors for clinical outcome under PD-1 blockade. Thus, a lower than median frequency of peripheral blood PD-1+CD56+ T-cells prior to starting anti-PD-1 checkpoint blockade is associated with superior clinical response, longer PFS and OS of stage IV melanoma patients.

Distinct phenotype and function of circulating Vδ1+ and Vδ2+ γδT-cells in acute and chronic hepatitis B

Hepatitis B virus (HBV) persists with global and virus-specific T-cell dysfunction, without T-cell based correlates of outcomes. To determine if γδT-cells are altered in HBV infection relative to clinical status, we examined the frequency, phenotype and function of peripheral blood Vδ1⁺ and Vδ2⁺γδT-cells by multi-parameter cytometry in a clinically diverse North American cohort of chronic hepatitis B (CHB), acute hepatitis B (AHB) and uninfected control subjects. We show that circulating γδT-cells were comprised predominantly of CD3^hiCD4^- Vδ2⁺γδT-cells with frequencies that were 2–3 fold higher among Asian than non-Asian Americans and inversely correlated with age, but without differences between CHB, AHB and control subjects. However, compared to control subjects, CHB was associated with increased Tbet^hiEomes^dim phenotype in Vδ2⁺γδT-cells whereas AHB was associated with increased Tbet^hiEomes^dim phenotype in Vδ1⁺γδT-cells, with significant correlations between Tbet/Eomes expression in γδT-cells with their expression of NK and T-cell activation and regulatory markers. As for effector functions, IFNγ/TNF responses to phosphoantigens or PMA/Ionomycin in Vδ2⁺γδT-cells were weaker in AHB but preserved in CHB, without significant differences for Vδ1⁺γδT-cells. Furthermore, early IFNγ/TNF responses in Vδ2⁺ γδT-cells to brief PMA/Ionomycin stimulation correlated inversely with serum ALT but not HBV DNA. Accordingly, IFNγ/TNF responses in Vδ2⁺γδT-cells were weaker in patients with CHB with hepatitis flare compared to those without hepatitis flares, and this functional deficit persisted beyond clinical resolution of CHB flare. We conclude that circulating γδT-cells show distinct activation and differentiatiation in acute and chronic HBV infection as part of lymphoid stress surveillance with potential role in clinical outcomes.

We examined circulating γδT-cells in a North American cohort with chronic hepatitis B (CHB) and acute hepatitis B (AHB) compared to uninfected control subjects. While frequencies and composition of circulating γδT-cells were preserved in AHB and CHB, γδT-cells showed distinct and innate phenotypes based on the expression of Tbet/Eomes in association with various NK/T-cell markers. Notably, IFNγ/TNF responses to phosphoantigens and PMA/Ionomycin were preserved in CHB, but weaker in AHB compared to uninfected control subjects, in association with NKG2A/CD94 but not PD1. Furthermore, early IFNγ/TNF responses in Vδ2⁺ γδT-cells to brief PMA/Ionomycin stimulation showed significant inverse correlations with serum alanine aminotransferase, a measure of hepatocellular injury, and were persistently deficient in CHB subjects with hepatitis flare compared to those without such flares. Finally, Vδ2⁺ γδT-cells were significantly enriched for Tbet^hiEomes^dim phenotype in associations with their expression of NK and T-cell activation and regulatory markers, suggesting a role for Tbet in γδT-cell differentiation and function. We conclude that circulating γδT-cells show distinct activation and differentiation in acute and chronic HBV infection as part of lymphoid stress surveillance with potential role in clinical outcomes.

Single Antibody Detection of T-Cell Receptor αβ Clonality by Flow Cytometry Rapidly Identifies Mature T-Cell Neoplasms and Monotypic Small CD8-Positive Subsets of Uncertain Significance

BACKGROUND

The diagnosis of T-cell neoplasms is often challenging, due to overlapping features with reactive T-cells and limitations of currently available T-cell clonality assays. The description of an antibody specific for one of two mutually exclusive T-cell receptor (TCR) β-chain constant regions (TRBC1) provide an opportunity to facilitate the detection of clonal TCRαβ T-cells based on TRBC-restriction.

METHODS

Twenty patients with mature T-cell neoplasms and 44 patients without evidence of T-cell neoplasia were studied. Peripheral blood (51), bone marrow (10), and lymph node (3) specimens were evaluated by 9-color flow cytometry including TRBC1 (CD2/CD3/CD4/CD5/CD7/CD8/CD45/TCRγδ/TRBC1 and/or CD2/CD3/CD4/CD5/CD7/CD8/CD26/CD45/TRBC1). Monophasic TRBC1 expression on any immunophenotypically distinct CD4-positive or CD8-positive/TCRγδ-negative T-cell subset was considered indicative of clonality.

RESULTS

Monophasic (clonal) TRBC1 expression was identified on immunophenotypically abnormal T-cells from all 20 patients with T-cell malignancies (100% sensitivity), including 17 cases with either >97% or <3% TRBC1-positive events, and three cases with monophasic homogenous TRBC1-dim expression. All immunophenotypically distinct CD4-positive and CD8-positive/TCRγδ-negative T-cell subsets from 44 patients without T-cell malignancies showed the expected mixture of TRBC1-positive and TRBC-1-negative subpopulations (non-clonal), except for seven patients (16%) with very small CD8-positive T-cell subsets exhibiting a monophasic (clonal) pattern.

CONCLUSION

Inclusion of a single anti-TRBC1 antibody into a diagnostic T-cell flow cytometry panel facilitates the rapid identification of T-cell neoplasms, in addition to small monotypic CD8-positive subsets of uncertain significance. © 2019 International Clinical Cytometry Society.

Aging, immune senescence, and immunotherapy: A comprehensive review

The advent of immune checkpoint inhibitors (ICIs) has changed the landscape of cancer treatment. Older adults represent the majority of cancer patients; however, direct data evaluating ICIs in this patient population is lacking. Aging is associated with changes in the immune system known as "immunosenescence" that could impact the efficacy and safety profile of ICIs. In this paper, we review aging-associated changes in the immune system as they may relate to cancer and immunotherapy, with mention of the effect of chronic viral infections and frailty. Furthermore, we summarize the current clinical evidence of ICI effectiveness and toxicity among older adults with cancer.

Vγ9Vδ2 T cells proliferate in response to phosphoantigens released from erythrocytes infected with asexual and gametocyte stage Plasmodium falciparum

Vγ9Vδ2 T cells, the dominant γδ T cell subset in human peripheral blood, are stimulated by phosphoantigens, of which (E)-4-Hydroxy-3-methyl-but-2-enyl pyrophosphate, is produced in the apicoplast of malaria parasites. Cell-free media from synchronised Plasmodium falciparum asexual ring, trophozoite, and schizont stage-cultures of high purity as well as media from ruptured schizont cultures, all stimulated Vγ9Vδ2 T cell proliferation, as did media from pure gametocyte cultures, whereas media from uninfected erythrocytes cultures did not. The media from ruptured schizont cultures and all the asexual and gametocyte stage cultures contained only background iron levels, suggesting that all erythrocyte haemoglobin is consumed as the parasites develop and supporting that the phosphoantigens were released from intact parasitized erythrocytes. The Vγ9Vδ2 T cell-stimulating agent was not affected by freezing, thawing or heating but was sensitive to phosphatase treatment, confirming its phosphoantigen identity. In summary, phosphoantigens are released from parasitised erythrocytes at all developmental blood stages.

Anti-Anisakis sp. antibodies in serum of patients with sepsis and their relationship with γδ T cells and disease severity

Immunosuppression in sepsis reduces both αβ and γδ T cell subsets. Anisakis sp. is a parasitic nematode with a high prevalence in Spain. Previous contact with the parasite is related to a decrease in γδ T cells. Anti-Anisakis antibodies were measured and related to αβ and γδ T cells in 114 septic patients versus 97 healthy controls. Significant differences were seen with respect to the groups with severe sepsis and septic shock where lower anti-Anisakis levels were observed. A similar decrease appeared in the case of specific IgM with significant differences between the groups of control/uncomplicated sepsis versus severe sepsis and septic shock. These differences were also apparent in the case of specific IgA. The lowest IgE levels were detected in the septic shock group. Anti-Anisakis IgG levels significantly increased in septic shock groups compared with the controls. We observed positive correlations among anti-Anisakis IgA levels and all γδ T cell subsets. There were negative correlations among IgA levels and APACHE and SOFA indices. Greater contact with the parasite (IgG) was directly related with septic shock, inflammation and markers of sepsis severity. A lack of protection in the mucosa (IgA and γδ T cells) was associated with the disease severity.

Heterogeneity of Specific CD4+ and CD8+ T Cells Stimulated by CMV pp65 and IE1 Antigens

Characterization of human cytomegalovirus-specific T cells (CMV-T) is of critical importance for their potential use in adoptive immunotherapy after allogeneic hematopoietic stem cell transplantation. Background frequencies of CMV-T in peripheral blood mononuclear cells (PBMCs) of CMV-seropositive healthy subjects are usually very low, hence the requirement for prolonged culture time and multiple stimulations to expand them. The evaluation of the end-culture specificity and composition has sometimes been neglected or difficult to assess in these settings. We explored the identity and the functionality of pp65-specific and IE1-specific T cells, enriched in short-term cultures from PBMCs. Antigen-specific T cells were further isolated by IFN-γ capture system and/or CD154 microbeads. Frequency of IE1-specific cytotoxic T cells in PBMCs secreting IFN-γ was higher compared with the pp65-specific one, whereas the latter cell types showed a higher median CD107a degranulation. Cell viability, rate of CMV-T increase, and multicytokine secretion profile after epitope-specific short-term cultures were heterogenous. T cells were mainly of late effector stages but they significantly dropped off upon CMV rechallenge with peptide pools. In parallel, CMV-T expansion was accompanied by a significant increase of cytotoxic naive/memory stem cells (CTLs), whereas the CD4 counterpart significantly increased only upon stimulation with IE1. Outcome was variable and showed donor and epitope dependency. Differences in human leukocyte antigen and epitope dominance and variability in the relative number of CD3 effector cells and IFN-γ/CD154 expression among healthy donors could reflect the observed individual CMV-specific cellular immunity. This heterogeneity raises points to be considered when approaching adoptive immunotherapy.

Immune biomarkers in older adults: Role of physical activity

Aging is associated with a decline in the normal functioning of the immune system. Several studies described the relationship between immunological alterations, including immunosenescence and inflammation, and aging or age-related outcomes, such as sarcopenia, depression, and neurodegenerative disorders. Physical activity is known to improve muscle function and to exert a number of benefits on older adult health, including reduced risk for heart and metabolic system chronic diseases. However, the positive influence of physical activity on the immune system has not been elucidated. In order to shed light on the role of physical activity in immune responses of older individuals, a number of immunological parameters comprising % lymphocyte subsets (CD3⁺, CD4⁺, CD8⁺, CD19⁺, and CD16⁺56⁺) and serum levels of neopterin and tryptophan metabolism products were evaluated in peripheral blood samples of older adults performing normal (N = 170) or reduced (N = 89) physical activity. In addition, the potential influence of other clinical and epidemiological factors was also considered. Results showed that subjects with reduced physical activity displayed significantly higher levels of CD4⁺/CD8⁺ ratio, kynurenine/tryptophan ratio, and serum neopterin, along with lower %CD19⁺ cells and tryptophan concentrations. Further, some immunological biomarkers were associated with cognitive impairment and functional status. These data contribute to reinforce the postulation that physical activity supports healthy aging, particularly by helping to protect the immunological system from aging-related changes.

Determination of Anti-Anisakis Simplex Antibodies and Relationship with αβ and γδ Lymphocyte Subpopulations in Patients with Crohn's Disease

BACKGROUND

The etiology of Crohn's disease (CD) is still unknown although new theories are based on defects in innate immunity. We have previously shown a decrease in γδ T cells in CD patients. Previous studies have shown a high prevalence of anti-A. simplex immunoglobulins in CD patients. The diminution of γδ T cells in the peripheral blood and intestinal mucosa of CD patients may create a state of immunosuppression that would facilitate A. simplex infection.

AIMS

To study the antibody responses to Anisakis antigens in Crohn's disease patients and its relationship with αβ and γδ T cell subsets.

METHODS

We recruited 81 CD patients and 81 healthy controls. αβ and γδ T cell subsets and anti-A. simplex antibodies were measured.

RESULTS

Levels of anti-A. simplex IgG and IgM were significantly increased in CD patients. Almost 20% of CD patients were positive for IgG and IgM anti-A. simplex versus only 3.7 and 2.5%, respectively, in normal subjects. However, lower specific IgA levels were observed in the group of CD patients versus healthy subjects. We found an association between CD3 + CD8 + γδ subset and IgM anti-A. simplex levels. In ileal cases and stricturing behavior of CD, we observed the highest levels of specific antibodies with the exception of anti-A. simplex IgA.

CONCLUSIONS

The relationship of specific antibodies with a γδ T cell deficiency makes these cell candidates to play a role in the immune response against Anisakis. In addition, anti-Anisakis antibodies could be considered as markers of risk of progression in CD.

Development of a Modular Assay for Detailed Immunophenotyping of Peripheral Human Whole Blood Samples by Multicolor Flow Cytometry

The monitoring of immune cells gained great significance in prognosis and prediction of therapy responses. For analyzing blood samples, the multicolor flow cytometry has become the method of choice as it combines high specificity on single cell level with multiple parameters and high throughput. Here, we present a modular assay for the detailed immunophenotyping of blood (DIoB) that was optimized for an easy and direct application in whole blood samples. The DIoB assay characterizes 34 immune cell subsets that circulate the peripheral blood including all major immune cells such as T cells, B cells, natural killer (NK) cells, monocytes, dendritic cells (DCs), neutrophils, eosinophils, and basophils. In addition, it evaluates their functional state and a few non-leukocytes that also have been associated with the outcome of cancer therapy. This DIoB assay allows a longitudinal and close-meshed monitoring of a detailed immune status in patients requiring only 2.0 mL of peripheral blood and it is not restricted to peripheral blood mononuclear cells. It is currently applied for the immune monitoring of patients with glioblastoma multiforme (IMMO-GLIO-01 trial, NCT02022384), pancreatic cancer (CONKO-007 trial, NCT01827553), and head and neck cancer (DIREKHT trial, NCT02528955) and might pave the way for immune biomarker identification for prediction and prognosis of therapy outcome.

Peripheral blood T-cell signatures from high-resolution immune phenotyping of γδ and αβ T-cells in younger and older subjects in the Berlin Aging Study II

Background

Aging and latent infection with Cytomegalovirus (CMV) are thought to be major factors driving the immune system towards immunosenescence, primarily characterized by reduced amounts of naïve T-cells and increased memory T-cells, potentially associated with higher morbidity and mortality. The composition of both major compartments, γδ as well as αβ T-cells, is altered by age and CMV, but detailed knowledge of changes to the γδ subset is currently limited.

Results

Here, we have surveyed a population of 73 younger (23–35 years) and 144 older (62–85 years) individuals drawn from the Berlin Aging Study II, investigating the distribution of detailed differentiation phenotypes of both γδ and αβ T-cells. Correlation of frequencies and absolute counts of the identified phenotypes with age and the presence of CMV revealed a lower abundance of Vδ2-positive and a higher amount of Vδ1-positive cells. We found higher frequencies of late-differentiated and lower frequencies of early-differentiated cells in the Vδ1+ and Vδ1-Vδ2-, but not in the Vδ2+ populations in elderly CMV-seropositive individuals confirming the association of these Vδ2-negative cells with CMV-immunosurveillance. We identified the highest Vδ1:Vδ2 ratios in the CMV-seropositive elderly. The observed increased CD4:CD8 ratios in the elderly were significantly lower in CMV-seropositive individuals, who also possessed a lower naïve and a larger late-differentiated compartment of CD8+ αβ T-cells, reflecting the consensus in the literature.

Conclusions

Our findings illustrate in detail the strong influence of CMV on the abundance and differentiation pattern of γδ T-cells as well as αβ T-cells in older and younger people. Mechanisms responsible for the phenotypic alterations in the γδ T-cell compartment, associated both with the presence of CMV and with age require further clarification.

Electronic supplementary material

The online version of this article (doi:10.1186/s12979-015-0052-x) contains supplementary material, which is available to authorized users.

Effects of aging on human leukocytes (part II): immunophenotyping of adaptive immune B and T cell subsets

Immunosenescence results from a continuous deterioration of immune responses resulting in a decreased response to vaccines. A well-described age-related alteration of the immune system is the decrease of de novo generation of T and B cells. In addition, the accumulation of memory cells and loss of diversity in antigen specificities resulting from a lifetime of exposure to pathogens has also been described. However, the effect of aging on subsets of γδTCR(+) T cells and Tregs has been poorly described, and the efficacy of the recall response to common persistent infections in the elderly remains obscure. Here, we investigated alterations in the subpopulations of the B and T cells among 24 healthy young (aged 19-30) and 26 healthy elderly (aged 53-67) individuals. The analysis was performed by flow cytometry using freshly collected peripheral blood. γδTCR(+) T cells were overall decreased, while CD4(+)CD8(-) cells among γδTCR(+) T cells were increased in the elderly. Helios(+)Foxp3(+) and Helios(-)Foxp3(+) Treg cells were unaffected with age. Recent thymic emigrants, based on CD31 expression, were decreased among the Helios(+)Foxp3(+), but not the Helios(-)Foxp3(+) cell populations. We observed a decrease in Adenovirus-specific CD4(+) and CD8(+) T cells and an increase in CMV-specific CD4(+) T cells in the elderly. Similarly, INFγ(+)TNFα(+) double-positive cells were decreased among activated T cells after Adenovirus stimulation but increased after CMV stimulation. The data presented here indicate that γδTCR(+) T cells might stabilize B cells, and functional senescence might dominate at higher ages than those studied here.

Lymphocyte Subsets in a Population of Nonfrail Elderly Individuals

Age-related frailty is characterized by increased vulnerability to stress due to decline in homeostatic reserve, which results in increased risk of adverse health outcomes including disability, hospitalization, and death. The relationship between frailty and immunological system alterations is well established. Thus, analysis of immunological changes, such as alterations in lymphocyte subsets, during senescence may provide useful markers for frailty and associated pathologies. Since reference ranges currently used for lymphocyte subsets do not specifically differentiate the elderly group, the aim of this study was to (1) establish reference ranges in nonfrail elderly individuals and (2) assess the evolution of these parameters with age. Further, the influence of other physiological and lifestyle factors was also evaluated. The study was performed on 144 elderly individuals (aged 65-95) from Galicia (in northwestern Spain). Percentages of lymphocyte subpopulations (CD3(+) T lymphocytes, CD4(+) T-helper lymphocytes, CD8(+) T-cytotoxic lymphocytes, CD19(+) B lymphocytes, and CD56(+)16(+) natural killer cells) were analyzed in peripheral blood by flow cytometry, and reference ranges were calculated. The individual status as nonfrail or prefrail did not markedly affect the immunological parameters, but an apparent influence of age was obtained for %CD3(+), %CD4(+), and %CD19(+) cells, all of which fell with increasing age. Women showed higher levels of %CD19(+) lymphocytes. No significant influence of smoking habits, physical activity, or drinking alcohol or caffeine beverages was observed. The results obtained may serve as a basis to establish comparisons between frail and nonfrail elderly individuals, in order to determine the usefulness of lymphocyte subsets as immunological biomarkers of frailty.

Pre-existing hypertension dominates γδT cell reduction in human ischemic stroke

T lymphocytes may play an important role in the evolution of ischemic stroke. Depletion of γδT cells has been found to abrogate ischemia reperfusion injury in murine stroke. However, the role of γδT cells in human ischemic stroke is unknown. We aimed to determine γδT cell counts and γδT cell interleukin 17A (IL-17A) production in the clinical setting of ischemic stroke. We also aimed to determine the associations of γδT cell counts with ischemic lesion volume, measures of clinical severity and with major stroke risk factors. Peripheral blood samples from 43 acute ischemic stroke patients and 26 control subjects matched on race and gender were used for flow cytometry and complete blood count analyses. Subsequently, cytokine levels and gene expression were measured in γδT cells. The number of circulating γδT cells was decreased by almost 50% (p = 0.005) in the stroke patients. γδT cell counts did not correlate with lesion volume on magnetic resonance diffusion-weighted imaging or with clinical severity in the stroke patients, but γδT cells showed elevated levels of IL-17A (p = 0.048). Decreased γδT cell counts were also associated with older age (p = 0.004), pre-existing hypertension (p = 0.0005) and prevalent coronary artery disease (p = 0.03), with pre-existing hypertension being the most significant predictor of γδT cell counts in a multivariable analysis. γδT cells in human ischemic stroke are reduced in number and show elevated levels of IL-17A. A major reduction in γδT lymphocytes also occurs in hypertension and may contribute to the development of hypertension-mediated stroke and vascular disease.

Is organic farming safer to farmers' health? A comparison between organic and traditional farming

Exposure to pesticides is a major public health concern, because of the widespread distribution of these compounds and their possible long term effects. Recently, organic farming has been introduced as a consumer and environmental friendly agricultural system, although little is known about the effects on workers' health. The aim of this work was to evaluate genetic damage and immunological alterations in workers of both traditional and organic farming. Eighty-five farmers exposed to several pesticides, thirty-six organic farmers and sixty-one controls took part in the study. Biomarkers of exposure (pyrethroids, organophosphates, carbamates, and thioethers in urine and butyrylcholinesterase activity in plasma), early effect (micronuclei in lymphocytes and reticulocytes, T-cell receptor mutation assay, chromosomal aberrations, comet assay and lymphocytes subpopulations) and susceptibility (genetic polymorphisms related to metabolism - EPHX1, GSTM1, GSTT1 and GSTP1 - and DNA repair-XRCC1 and XRCC2) were evaluated. When compared to controls and organic farmers, pesticide farmers presented a significant increase of micronuclei in lymphocytes (frequency ratio, FR=2.80) and reticulocytes (FR=1.89), chromosomal aberrations (FR=2.19), DNA damage assessed by comet assay (mean ratio, MR=1.71), and a significant decrease in the proportion of B lymphocytes (MR=0.88). Results were not consistent for organic farmers when compared to controls, with a 48% increase of micronuclei in lumphocytes frequency (p=0.016) contrasted by the significant decreases of TCR-Mf (p=0.001) and %T (p=0.001). Our data confirm the increased presence of DNA damage in farmers exposed to pesticides, and show as exposure conditions may influence observed effects. These results must be interpreted with caution due to the small size of the sample and the unbalanced distribution of individuals in the three study groups.

TCRγδ(+)CD4(-)CD8(-) T cells suppress the CD8(+) T-cell response to hepatitis B virus peptides, and are associated with viral control in chronic hepatitis B

The immune mechanisms underlying failure to achieve hepatitis B e antigen (HBeAg) seroconversion associated with viral control in chronic hepatitis B (CHB) remain unclear. Here we investigated the role of CD4(-)CD8(-) T (double-negative T; DNT) cells including TCRαβ(+) DNT (αβ DNT) and TCRγδ(+) DNT (γδ DNT) cells. Frequencies of circulating DNT cell subsets were measured by flow cytometry in a retrospective cohort of 51 telbivudine-treated HBeAg-positive CHB patients, 25 immune tolerant carriers (IT), 33 inactive carriers (IC), and 37 healthy controls (HC). We found that γδ DNT cell frequencies did not significantly change during treatment, being lower at baseline (P = 0.019) in patients with HBeAg seroconversion after 52 weeks of antiviral therapy (n = 20) than in those without (n = 31), and higher in the total CHB and IT than IC and HC groups (P<0.001). αβ DNT cell frequencies were similar for all groups. In vitro, γδ DNT cells suppressed HBV core peptide-stimulated interferon-γ and tumor necrosis factor-α production in TCRαβ(+)CD8(+) T cells, which may require cell-cell contact, and could be partially reversed by anti-NKG2A. These findings suggest that γδ DNT cells limit CD8(+) T cell response to HBV, and may impede HBeAg seroconversion in CHB.

Splenic lymphoid subsets with less well-recognized phenotypes mimic aberrant antigen expression

OBJECTIVES

Flow cytometry can assist in the diagnosis of lymphoma by identifying aberrant antigen expression. Recognition of aberrancy requires knowledge of the phenotype of normal lymphoid cells.

METHODS

Lymphoid subsets were characterized in 20 spleens removed for traumatic rupture, using 8-color flow cytometry.

RESULTS

Normal variation in splenic lymphoid subsets was highlighted and several well-recognized subsets were identified: CD5+ B cells (20/20 specimens), CD7- T cells (20/20), and CD3 brightγδT cells (16/20). In addition, less well-recognized lymphoid subsets that resemble those described in lymphoma were identified in all specimens: CD5- T cells (4.5 ± 5.1% of T cells), CD2- natural killer (NK) cells (38 ± 7% of NK cells), and CD7dim+ NK cells. Similar populations were identified in 20 control peripheral blood specimens, where they represented a smaller proportion of total lymphoid cells.

CONCLUSIONS

Familiarity with the phenotype of normal lymphoid subsets can help prevent misinterpreting flow cytometric data. Furthermore, in the context of neoplastic cells, the phenotype may suggest expanded normal subsets rather than aberrant antigen expression.

Ex vivo restimulation of human PBMC expands a CD3+CD4-CD8- γδ+ T cell population that can confound the evaluation of CD4 and CD8 T cell responses to vaccination

The measurement of vaccine-induced humoral and CD4⁺ and CD8⁺ cellular immune responses represents an important correlate of vaccine efficacy. Accurate and reliable assays evaluating such responses are therefore critical during the clinical development phase of vaccines. T cells play a pivotal role both in coordinating the adaptive and innate immune responses and as effectors. During the assessment of cell-mediated immunity (CMI) in subjects participating in a large-scale influenza vaccine trial, we identified the expansion of an IFN-γ-producing CD3⁺CD4⁻CD8⁻γδ⁺ T cell population in the peripheral blood of 90/610 (15%) healthy subjects. The appearance of CD3⁺CD4⁻CD8⁻γδ⁺ T cells in the blood of subjects was transient and found to be independent of the study cohort, vaccine group, subject gender and ethnicity, and ex vivo restimulation conditions. Although the function of this population and relevance to vaccination are unclear, their inclusion in the total vaccine-specific T-cell response has the potential to confound data interpretation. It is thus recommended that when evaluating the induction of IFN-γ-producing CD4⁺ and CD8⁺ immune responses following vaccination, the CD3⁺CD4⁻CD8⁻γδ⁺ T cells are either excluded or separately enumerated from the overall frequency determination.

Endocrine and immunological parameters in individuals involved in Prestige spill cleanup tasks seven years after the exposure

In November 2002 the oil tanker Prestige spilled 63,000tonnes of heavy oil off the northwest coast of Spain, impacting more than 1000km of coastline. A general concern led to a huge mobilization of human and technical resources, and more than 300,000 people participated in cleanup activities, which lasted up to 10months. Some endocrine and immunological alterations were reported in Prestige oil exposed subjects for several months. Therefore, the objective of this study was to evaluate if these alterations are still present seven years after the exposure. Fifty-four individuals exposed for at least 2months were compared to 50 matched referents. Prolactin and cortisol plasma concentrations, percentages of lymphocyte subsets (CD3(+), CD4(+), CD8(+), CD19(+), and CD56(+)16(+)), plasma levels of circulating cytokines (interleukin (IL) 2, IL4, IL6, IL10, tumour necrosis factor α, and interferon γ), and serum concentrations of neopterin, tryptophan and kynurenine were determined in peripheral blood samples. Results showed significant differences in exposed individuals vs. referents only in cortisol (increase), kynurenine and %CD16(+)56(+) lymphocytes (both decrease). Time of exposure to the oil or using protective clothes did not influence the results, but effect of using protective mask was observed on neopterin, %CD8(+), CD4(+)/CD8(+) ratio and IL4. Surveillance of the exposed individuals for early detection of possible health problems related to the endocrine or immunological systems is recommended.

Age-associated alterations in γδ T-cells are present predominantly in individuals infected with Cytomegalovirus

Background

Despite the common perception that latent Cytomegalovirus (CMV) infection is usually symptom-free, emerging epidemiological evidence suggests that it may in fact be associated with higher mortality over extended follow-up. Mechanisms responsible for this potentially important effect are unclear. CMV infection is known to have a large impact on the distribution of T cell phenotypes, especially the accumulation of late-stage differentiated CD8⁺, as well as Vδ2^- γδ T-cells, which are the main subset of γδ T-cells involved in anti-CMV immunity. Its impact on γδ T-cells in the aging context is less well-defined.

Results

Here, we investigated a group of healthy individuals aged between 21 and 89 years, in order to correlate the frequency and differentiation status of γδ T-cells with age. We found that these parameters were only marginally influenced by age, but were marked in people with a latent CMV infection. Thus, we observed a significant age-associated accumulation of late-differentiated T-cells within the Vδ2^- population, but only in CMV-seropositive donors. There was also a strong trend towards reduced frequency of early-differentiated cells within the Vδ2^- phenotype. Older people had significantly higher anti-CMV IgG titers, which in turn correlated significantly with a lower Vδ2⁺/Vδ2^- ratio and a shift from early- to a late-differentiated Vδ2^- T-cell phenotype.

Conclusions

Our findings demonstrate a strong influence of CMV on γδ T-cells during human ageing, similar to that observed for αβ T-cells. Differences between donors of different ages are more marked in CMV-infected individuals. The biological implications of this potent age-associated CMV-mediated immune-modulation require clarification.