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Background Chronic inflammation is prevalent with antiretroviral therapy (ART)-suppressed human immunodeficiency virus (HIV) infection and one immune cell subset putatively driving this phenomenon is TIGIT+ γδ T cells. Methods To elucidate γδ T-cell phenotypic diversity, spectral flow cytometry was performed on blood lymphocytes from individuals of a HIV and aging cohort and data were analyzed using bioinformatic platforms. Plasma inflammatory markers were measured and correlated with γδ T-cell subset frequencies. Results Thirty-nine distinct γδ T-cell subsets were identified (22 Vδ1+, 14 Vδ2+, and 3 Vδ1−Vδ2−Vγ9+) and TIGIT was nearly exclusively found on the Vδ1+CD45RA+CD27− effector populations. People with ART-suppressed HIV infection (PWH) exhibited high frequencies of distinct clusters of Vδ1+ effectors distinguished via CD8, CD16, and CD38 expression. Among Vδ2+ cells, most Vγ9+ (innate-like) clusters were lower in PWH; however, CD27+ subsets were similar in frequency between participants with and without HIV. Comparisons by age revealed lower 'naive' Vδ1+CD45RA+CD27+ cells in older individuals, regardless of HIV status. Plasma inflammatory markers were selectively linked to subsets of Vδ1+ and Vδ2+ cells. Conclusions These results further elucidate γδ T-cell subset complexity and reveal distinct alterations and connections with inflammatory pathways of Vδ1+ effector and Vδ2+ innate-like subsets during ART-suppressed HIV infection. [ABSTRACT FROM AUTHOR]

Gliomas are histologically defined as low-grade gliomas (LGG) and high-grade gliomas (HGG). The most common type of HGG is the glioblastoma (GBM). We aimed to determine the immunological characteristics of CD3 T-cells, Vδ1 T-cells, and microglia/macrophages infiltrating brain gliomas. We collected 24 formalin-fixed paraffin-embedded samples issued from 19 cases of GBM and 5 cases of LGG. An immunohistochemical analysis was performed using anti-CD3, anti-Vδ1, and anti-iba-1 antibodies. Labelling indexes (LI) of CD3 and Vδ1 were evaluated quantitatively, and other CD3, Vδ1, and iba-1 staining characteristics were evaluated qualitatively. The median age of patients was 49 years in GBM and 52 years in LGG. The sex ratio was 1.4 and GBM predominated in males (p = 0.05). In GBM, the medians of CD3-LI and Vδ1-LI were 30 and 3.5 respectively. CD3-LI inversely correlated with survival in GBM cases (r = − 0.543; p = 0.016). CD3 staining intensity correlated with CD3-LI (p < 0.0001) and with the survival in GBM cases (p = 0.003). Compared to LGG, the CD3-LI, the intensity of intra-tumoral Vδ1 staining, and the amount of iba-1 were higher in GBM (p = 0.042; p = 0.014; and p = 0.001 respectively). The iba-1 organization was more amoeboid in older patients and more branched in younger patients (p = 0.028) and tended to be more amoeboid in cases with high iba-1 amount (p = 0.09). Our results suggest that a high level of CD3-LI and a strong intra-tumoral infiltration of Vδ1 T-cells as well as a high involvement of TAM can be considered potential markers of poor prognosis of GBM. However, this requires further studies on more balanced GBM-LGG sample, including an expanded panel of biomarkers. [ABSTRACT FROM AUTHOR]

Effector capabilities of γδ T cells are evident in Plasmodium infection in young and adult individuals, while children are the most vulnerable groups affected by malaria. Here, we aimed to investigate the age-dependent phenotypic composition of Vδ1+, Vδ2+, and Vδ3+ T cells in children living in endemic malaria areas and how this differs between children that will develop symptomatic and asymptomatic Plasmodium falciparum infections. Flow cytometric profiling of naïve and effector peripheral blood γδ T cells was performed in 6 neonates, 10 adults, and 52 children. The study population of young children, living in the same malaria endemic region of Ghana, was monitored for symptomatic vs asymptomatic malaria development for up to 42 weeks after peripheral blood sampling at baseline. For the Vδ2+ T cell population, there was evidence for an established type 1 effector phenotype, characterized by CD94 and CD16 expression, as early as 1 year of life. This was similar among children diagnosed with symptomatic or asymptomatic malaria. In contrast, the proportion of type 2- and type 3-like Vδ2 T cells declined during early childhood. Furthermore, for Vδ1+ and Vδ3+ T cells, similar phenotypes of naïve (CD27+) and type 1 effector (CD16+) cells were observed, while the proportion of CD16+ Vδ1+ T cells was highest in children with asymptomatic malaria. In summary, we give evidence for an established adult-like γδ T cell compartment in early childhood with similar biology of Vδ1+ and Vδ3+ T cells. Moreover, the data supports the idea that type 1 effector Vδ1+ T cells mediate the acquisition of and can potentially serve as biomarker for natural immunity to P. falciparum infections in young individuals from malaria-endemic settings. [ABSTRACT FROM AUTHOR]

Effector capabilities of γδ T cells are evident in Plasmodium infection in young and adult individuals, while children are the most vulnerable groups affected by malaria. Here, we aimed to investigate the age-dependent phenotypic composition of Vδ1+, Vδ2+, and Vδ3+ T cells in children living in endemic malaria areas and how this differs between children that will develop symptomatic and asymptomatic Plasmodium falciparum infections. Flow cytometric profiling of naïve and effector peripheral blood γδ T cells was performed in 6 neonates, 10 adults, and 52 children. The study population of young children, living in the same malaria endemic region of Ghana, was monitored for symptomatic vs asymptomatic malaria development for up to 42 weeks after peripheral blood sampling at baseline. For the Vδ2+ T cell population, there was evidence for an established type 1 effector phenotype, characterized by CD94 and CD16 expression, as early as 1 year of life. This was similar among children diagnosed with symptomatic or asymptomatic malaria. In contrast, the proportion of type 2- and type 3-like Vδ2 T cells declined during early childhood. Furthermore, for Vδ1+ and Vδ3+ T cells, similar phenotypes of naïve (CD27+) and type 1 effector (CD16+) cells were observed, while the proportion of CD16+ Vδ1+ T cells was highest in children with asymptomatic malaria. In summary, we give evidence for an established adult-like γδ T cell compartment in early childhood with similar biology of Vδ1+ and Vδ3+ T cells. Moreover, the data supports the idea that type 1 effector Vδ1+ T cells mediate the acquisition of and can potentially serve as biomarker for natural immunity to P. falciparum infections in young individuals from malaria-endemic settings.

Background: Gamma-delta (γδ) T cells comprise an important subset of human T cells, responding to viral and bacterial infections, and are significant for cancer immunosurveillance. Human γδ T cells are divided into 5 major subsets, namely Vδ1-Vδ5, of which the latter 3 have limited available literature. At present, Vδ2 is the most studied subpopulation., Objectives: In the current paper, we focused on non-Vδ2 cells in chronic lymphocytic leukemia (CLL). We assessed the expression of co-inhibitory checkpoint receptors (CTLA-4, PD-1 and TIGIT) and co-stimulatory (CD226 and NKp30) molecules separately on Vδ1 and Vδ3-Vδ5 cells., Material and Methods: We assessed γδ T cells for their expression of both cytotoxicity-related (NKp30, CD226) and co-inhibitory (PD-1, TIGIT) molecules with flow cytometry in CLL patients. Moreover, we evaluated the expression of TIGIT and CD226 ligand (PVR , CD155) in neoplastic B cells in CLL patients with quantitative real-time polymerase chain reaction (qPCR)., Results: A significant accumulation of Vδ1 T cells was noted, while no difference was observed in the total percentage of Vδ2 cells. Contrary to our initial hypothesis, the impact of CLL burden on CD226 and TIGIT expression was lower than anticipated. The former tends to be lower in more advanced disease. Finally, a strong upregulation of CD155 (PVR) was noted on CLL-derived B cells when compared to healthy B cells., Conclusions: Chronic lymphocytic leukemia regulates the expression of the CD155-CD226/TIGIT axis. Contrary to expectations, the ligand is significantly more affected than the receptors. Nevertheless, the relatively high expression of CD155 and TIGIT makes CLL an interesting target for anti-TIGIT immunotherapy.

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.

Background: γδT cell lymphoma (γδ TCL) is a class of hematopoietic malignancy that expresses the γδ T cell receptor (TCR) with a low incidence. Determining the clonal proliferation of γδT cells is important for the diagnosis of such malignancies. Few studies have used flow cytometry to detect VδTCR and its subtypes (Vδ1 and Vδ2) at the protein level, although it is a practical method for determining the neoplastic γδT cells.Methods: A TCRVδ-based 10-color protocol was designed for the detection of malignant proliferation of γδT subtype cells by multiparameter flow cytometry, and the diagnostic results were compared with the gene rearrangement results.Results: All 19 cases of γδ TCL were positive for cluster of differentiation 3 (CD3) and TCR γδ and presented with abnormal distribution patterns of Vδ1 and Vδ2, of which 16 of the 19 cases showed a restricted Vδ1 staining pattern and the remaining three cases lacked the expression of either Vδ1 or Vδ2. Among the 10 normal controls and 11 patients with reactively higher CD4 and CD8 double-negative ratio, the percentage of Vδ2 positive events (range: 16.4–99.0%) was significantly higher than that of Vδ1 (range: 0–50.5%; p < 0.0001), and all cases had a normal Vδ distribution pattern. To detect clonality, there was no difference in the detection rate between the TCRVδ analysis and the gene scanning techniques (p = 1.000) with a high degree of coincidence (Kappa = 0.850, p < 0.001). The heteroduplex analysis was less sensitive than the other methods but was more specific (100%) than the gene scanning techniques, and the TCRVδ subtype analysis had the highest sensitivity, specificity, positive predictive value, and negative predictive value. Compared with molecular methods, immunophenotyping is able to distinguish the T cell lineage.Conclusion: The γδT panel, based on the TCRVδ antibody by flow cytometry, could be advantageous for the rapid identification of suspected γδTCL.

Elimination of the latent HIV reservoir remains a major barrier to achieving an HIV cure. In this review, we discuss the cytolytic nature of human gamma delta T cells and highlight the emerging evidence that they can target and eliminate HIV-infected T cells. Based on observations from human clinical trials assessing gamma delta immunotherapy in oncology, we suggest key questions and research priorities for the study of these unique T cells in HIV cure research.

Abstract Background Previous studies reported HIV infection alters the distribution and function of γδ T cells and their subsets. γδ T phenotypes in healthy and diseased individuals has received little attention in Ethiopia. We conducted this study to analyze the distribution of γδ T cells, the subsets and levels of expression of activation (CD38), exhaustion or anergy (CD95, PD1), adhesion (N-CAM/CD56 and CD103), among HIV and TB infected patients. Method The distributions of total γδ T cells, Vδ1 and Vδ2 T cells subsets were analyzed in clinical samples collected from asymptomatic HIV, pulmonary TB patients and apparently healthy controls. Multicolor flow cytometry and IFN-γ ELISA were used to assess surface markers and functional responses of Vδ2 T cells to isopentenyl pyrophosphate stimulation, respectively. Result A total of 52 study participants were enrolled in this study, 22 HIV + TB-, 10 HIV-TB+ and 20 healthy controls. No significant differences were observed in the distribution of total γδ T cells and in the proportion of Vδ1 subsets in all study groups, though slightly higher proportions were observed in HIV + TB- patients for the latter, of borderline statistical significance (p = 0.07). However, the proportion of Vδ2 T cells, as well as the IFN-γ response to IPP stimulation, was significantly reduced in HIV + TB- patients compared to healthy controls (p

Background: γδT cell lymphoma (γδ TCL) is a class of hematopoietic malignancy that expresses the γδ T cell receptor (TCR) with a low incidence. Determining the clonal proliferation of γδT cells is important for the diagnosis of such malignancies. Few studies have used flow cytometry to detect VδTCR and its subtypes (Vδ1 and Vδ2) at the protein level, although it is a practical method for determining the neoplastic γδT cells. Methods: A TCRVδ-based 10-color protocol was designed for the detection of malignant proliferation of γδT subtype cells by multiparameter flow cytometry, and the diagnostic results were compared with the gene rearrangement results. Results: All 19 cases of γδ TCL were positive for cluster of differentiation 3 (CD3) and TCR γδ and presented with abnormal distribution patterns of Vδ1 and Vδ2, of which 16 of the 19 cases showed a restricted Vδ1 staining pattern and the remaining three cases lacked the expression of either Vδ1 or Vδ2. Among the 10 normal controls and 11 patients with reactively higher CD4 and CD8 double-negative ratio, the percentage of Vδ2 positive events (range: 16.4–99.0%) was significantly higher than that of Vδ1 (range: 0–50.5%; p < 0.0001), and all cases had a normal Vδ distribution pattern. To detect clonality, there was no difference in the detection rate between the TCRVδ analysis and the gene scanning techniques (p = 1.000) with a high degree of coincidence (Kappa = 0.850, p < 0.001). The heteroduplex analysis was less sensitive than the other methods but was more specific (100%) than the gene scanning techniques, and the TCRVδ subtype analysis had the highest sensitivity, specificity, positive predictive value, and negative predictive value. Compared with molecular methods, immunophenotyping is able to distinguish the T cell lineage. Conclusion: The γδT panel, based on the TCRVδ antibody by flow cytometry, could be advantageous for the rapid identification of suspected γδTCL. [ABSTRACT FROM AUTHOR]

Elimination of the latent HIV reservoir remains a major barrier to achieving an HIV cure. In this review, we discuss the cytolytic nature of human gamma delta T cells and highlight the emerging evidence that they can target and eliminate HIV-infected T cells. Based on observations from human clinical trials assessing gamma delta immunotherapy in oncology, we suggest key questions and research priorities for the study of these unique T cells in HIV cure research. [ABSTRACT FROM AUTHOR]

Gamma-delta (γδ) T cells are unconventional T cells that help control cytomegalovirus (CMV) infection in adults. γδ T cells develop early in gestation, and a fetal public γδ T cell receptor (TCR) clonotype is detected in congenital CMV infections. However, age-dependent γδ T cell responses to primary CMV infection are not well-understood. Flow cytometry and TCR sequencing was used to comprehensively characterize γδ T cell responses to CMV infection in a cohort of 32 infants followed prospectively from birth. Peripheral blood γδ T cell frequencies increased during infancy, and were higher among CMV-infected infants relative to uninfected. Clustering analyses revealed associations between CMV infection and activation marker expression on adaptive-like Vδ1 and Vδ3, but not innate-like Vγ9Vδ2 γδ T cell subsets. Frequencies of NKG2C+CD57+ γδ T cells were temporally associated with the quantity of CMV shed in saliva by infants with primary infection. The public γδ TCR clonotype was only detected in CMV-infected infants

Abstract HIV infection is associated with a rapid and sustained inversion of the Vδ1:Vδ2 T‐cell ratio in peripheral blood. Studies of antiretroviral therapy (ART)‐treated cohorts suggest that ART is insufficient to reconstitute either the frequency or function of the γδ T‐cell subset. Recent advances are now beginning to shed light on the relationship between microbial translocation, chronic inflammation, immune ageing and γδ T‐cell immunology. Here, we review the impact of acute, chronic untreated and treated HIV infection on circulating and mucosal γδ T‐cell subsets and highlight novel approaches to harness γδ T cells as components of anti‐HIV immunotherapy.

Recent advances in γδ T cell biology have focused on the unique attributes of these cells and their role in regulating innate and adaptive immunity, promoting tissue homeostasis, and providing resistance to various disorders. Numerous bacterial and viral pathogens, including human immunodeficiency virus-1 (HIV), greatly alter the composition of γδ T cells in vivo. Despite the effectiveness of antiretroviral therapy (ART) in controlling HIV and restoring health in those affected, γδ T cells are dramatically impacted during HIV infection and fail to reconstitute to normal levels in HIV-infected individuals during ART for reasons that are not clearly understood. Importantly, their role in controlling HIV infection, and the implications of their failure to rebound during ART are also largely unknown and understudied. Here, we review important aspects of human γδ T cell biology, the effector and immunomodulatory properties of these cells, their prevalence and function in HIV, and their immunotherapeutic potential.

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. [ABSTRACT FROM AUTHOR]

Abstract: Although there exist case reports describing the association of clonal expansion of γδ T cells with chronic acquired pure red cell aplasia (PRCA), there is no consensus regarding whether clonal expansion of γδ T cells are generally found in chronic PRCA. We examined the γδ T cell receptor repertoire in 19 PRCA patients and found that there was a difference in γδ T-cell repertoires between PRCA patients and healthy donors. We observed an increase in Vδ1 γδ T cells and a decrease in Vδ2 T cells in PRCA patients. CDR3δ1 size distribution patterns were skewed in 9 out of 13 PRCA patients examined, although the skewing was also observed in 7 out of 10 healthy individuals. No significant changes were present in CDR3δ1 size distribution between PRCA patients and healthy donors. Moreover, no apparent consensus amino acid motifs were identified in PRCA patients. Expansion of Vδ1 T cells and depletion of Vδ2 T cells are unique features for chronic acquired PRCA but expansion of Vδ1 T cells does not seem to be the consequence of CDR3-dependent selection. We conclude that clonal expansion of Vδ1 T cells is not a general feature for chronic acquired PRCA. [Copyright &y& Elsevier]

It has been suggested that γδ T cells are involved in certain autoimmune disorders. To establish reference data for clinical studies to explore the role of γδ T cells in autoimmune bone marrow failure syndrome, we examined the γδ T-cell repertoire in 120 healthy Japanese individuals by flow cytometry. The average numbers of T lymphocytes in blood were as follows: 1,084 ± 369 (SD) αβ T cells, 68 ± 44 γδ T cells, 16 ± 12 Vδ1 T cells, and 43 ± 36 Vδ2 T cells (/μl). Absolute numbers of γδ T cells decreased with aging (R = -0.378, P < 0.001). The decrease of γδ T cells was the result of reduction of Vδ2, but not of Vδ1, T cells. Numbers of Vδ2 T cells were significantly higher in male than in female donors (P = 0.007). The Vδ2 T cells but not Vδ1 T cells showed a rapid reduction in cell numbers on mitogen stimulation, which was accompanied by modest down-regulation of Bcl-2 protein expression. These results indicate that age and gender have a major impact on γδ T-cell repertoire in Japanese donors, as well as European and American donors. The age-related decrease of Vδ2 T cells may be explained by their susceptibility to activation-induced cell death. [ABSTRACT FROM AUTHOR]

TCR γδ+ cells constitute <5% of all circulating T cells in healthy, adult Caucasians, and Vδ1+ cells constitute a minority of these cells. In contrast to TCR αβ+ cells, their repertoire is selected extrathymically by environmental antigens. Although increased frequencies of Vδ1+ cells are found in several diseases, their function remains obscure. Here we show that the frequency of peripheral blood γδ T cells in healthy West Africans is about twice that of Caucasians, mainly due to a 5-fold increase in Vδ1+ cells, which is consequently the dominant subset. No age dependency of Vδ1 frequencies was identified and the Vδ1+ cells in the African donors did not show preferential Vγ chain usage. Analysis of the CDR3 region size did not reveal any particular skewing of the Vδ1 repertoire, although oligoclonality was more pronounced in adults compared to children. The proportions of CD8+, CD38+ and CD45RAhiCD45RO– cells within the Vδ1+ subset were higher in the African than in the European donors, without obvious differences in expression of activation markers. No significant correlations between levels of Vδ1+ cells and environmental antigens or immunological parameters were identified. Taken together, the evidence argues against a CDR3-restricted, antigen-driven expansion of Vδ1+ cells in the African study population. Our study shows that high frequencies of TCR γδ+ cells with dominance of the Vδ1+ subset can occur at the population level in healthy people, raising questions about the physiological role of Vδ1+ T cells in the function and regulation of the immune system. [ABSTRACT FROM PUBLISHER]

We have determined the distribution of Tγδ cells in the peripheral blood of 44 patients with rheumatoid arthritis and in 36 healthy controls. In addition, paired blood and synovial fluid samples were obtained from seven patients with RA. The monoclonal antibodies A13, BB3 and TiγA, which are specific for the Vδ1, Vδ2 and Vγ9 gene products respectively, were used to define Tγδ subsets. Tγδ+ cells expressed as a percentage of CD3+ lymphocytes were reduced in RA peripheral blood compared with the control group (3.9% ± 0.5 versus 5.7% ± 0.7; <0.0001). There was a reduction in the Vδ9/Vδ2+ subset (from 5.6% ± 1.2 to 1.7% ± 0.4) leading to a change in the mean ratio of Vδ2/Vδ1+ cells from 4.3 in normal subjects to 1.1 (<0.002). No statistical difference was observed in Tγδ cell numbers in synovial fluid compared with the paired blood samples (4.0% ± 1.1 in blood and 4.4% ± 1.4 in synovial fluid). Also the distribution of Vδ2+ and Vδ1+ cells was similar in the two compartments and a similar alteration in subset distribution was found in blood and synovial fluid. These findings do not indicate a selective accumulation of a specific Tγδ subset in RA synovial effusions. [ABSTRACT FROM PUBLISHER]

Gamma-delta (γδ) T cells are unconventional T cells that help control cytomegalovirus (CMV) infection in adults. γδ T cells develop early in gestation, and a fetal public γδ T cell receptor (TCR) clonotype is detected in congenital CMV infections. However, age-dependent γδ T cell responses to primary CMV infection are not well-understood. Flow cytometry and TCR sequencing was used to comprehensively characterize γδ T cell responses to CMV infection in a cohort of 32 infants followed prospectively from birth. Peripheral blood γδ T cell frequencies increased during infancy, and were higher among CMV-infected infants relative to uninfected. Clustering analyses revealed associations between CMV infection and activation marker expression on adaptive-like Vδ1 and Vδ3, but not innate-like Vγ9Vδ2 γδ T cell subsets. Frequencies of NKG2C + CD57 + γδ T cells were temporally associated with the quantity of CMV shed in saliva by infants with primary infection. The public γδ TCR clonotype was only detected in CMV-infected infants <120 days old and at lower frequencies than previously described in fetal infections. Our findings support the notion that CMV infection drives age-dependent expansions of specific γδ T cell populations, and provide insight for novel strategies to prevent CMV transmission and disease.

Recent advances in γδ T cell biology have focused on the unique attributes of these cells and their role in regulating innate and adaptive immunity, promoting tissue homeostasis, and providing resistance to various disorders. Numerous bacterial and viral pathogens, including human immunodeficiency virus-1 (HIV), greatly alter the composition of γδ T cells in vivo. Despite the effectiveness of antiretroviral therapy (ART) in controlling HIV and restoring health in those affected, γδ T cells are dramatically impacted during HIV infection and fail to reconstitute to normal levels in HIV-infected individuals during ART for reasons that are not clearly understood. Importantly, their role in controlling HIV infection, and the implications of their failure to rebound during ART are also largely unknown and understudied. Here, we review important aspects of human γδ T cell biology, the effector and immunomodulatory properties of these cells, their prevalence and function in HIV, and their immunotherapeutic potential. [ABSTRACT FROM AUTHOR]

HIV infection is associated with a rapid and sustained inversion of the Vδ1:Vδ2 T‐cell ratio in peripheral blood. Studies of antiretroviral therapy (ART)‐treated cohorts suggest that ART is insufficient to reconstitute either the frequency or function of the γδ T‐cell subset. Recent advances are now beginning to shed light on the relationship between microbial translocation, chronic inflammation, immune ageing and γδ T‐cell immunology. Here, we review the impact of acute, chronic untreated and treated HIV infection on circulating and mucosal γδ T‐cell subsets and highlight novel approaches to harness γδ T cells as components of anti‐HIV immunotherapy. [ABSTRACT FROM AUTHOR]