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Accurate assessment of SARS-CoV-2 immunity is critical in evaluating vaccine efficacy and devising public health policies. Whilst the exact nature of effective immunity remains incompletely defined, SARS-CoV-2-specific T-cell responses are a critical feature that will likely form a key correlate of protection against COVID-19. Here, we developed and optimized a high-throughput whole blood-based assay to determine the T-cell response associated with prior SARS-CoV-2 infection and/or vaccination amongst 231 healthy donors and 68 cancer patients. Following overnight in vitro stimulation with SARS-CoV-2-specific peptides, blood plasma samples were analysed for TH 1-type cytokines. Highly significant differential IFN-γ+ /IL-2+ SARS-CoV-2-specific T-cell responses were seen amongst previously infected COVID-19-positive healthy donors in comparison with unknown / naïve individuals (p < 0·0001). IFN-γ production was more effective at identifying asymptomatic donors, demonstrating higher sensitivity (96·0% vs. 83·3%) but lower specificity (84·4% vs. 92·5%) than measurement of IL-2. A single COVID-19 vaccine dose induced IFN-γ and/or IL-2 SARS-CoV-2-specific T-cell responses in 116 of 128 (90·6%) healthy donors, reducing significantly to 27 of 56 (48·2%) when measured in cancer patients (p < 0·0001). A second dose was sufficient to boost T-cell responses in the majority (90·6%) of cancer patients, albeit IFN-γ+ responses were still significantly lower overall than those induced in healthy donors (p = 0·034). Three-month post-vaccination T-cell responses also declined at a faster rate in cancer patients. Overall, this cost-effective standardizable test ensures accurate and comparable assessments of SARS-CoV-2-specific T-cell responses amenable to widespread population immunity testing, and identifies individuals at greater need of booster vaccinations.

COVID-19 is characterized by profound lymphopenia in the peripheral blood, and the remaining T cells display altered phenotypes, characterized by a spectrum of activation and exhaustion. However, antigen-specific T cell responses are emerging as a crucial mechanism for both clearance of the virus and as the most likely route to long-lasting immune memory that would protect against re-infection. Therefore, T cell responses are also of considerable interest in vaccine development. Furthermore, persistent alterations in T cell subset composition and function post-infection have important implications for patients’ long-term immune function. In this review, we examine T cell phenotypes, including those of innate T cells, in both peripheral blood and lungs, and consider how key markers of activation and exhaustion correlate with, and may be able to predict, disease severity. We focus on SARS-CoV-2-specific T cells to elucidate markers that may indicate formation of antigen-specific T cell memory. We also examine peripheral T cell phenotypes in recovery and the likelihood of long-lasting immune disruption. Finally, we discuss T cell phenotypes in the lung as important drivers of both virus clearance and tissue damage. As our knowledge of the adaptive immune response to COVID-19 rapidly evolves, it has become clear that while some areas of the T cell response have been investigated in some detail, others, such as the T cell response in children remain largely unexplored. Therefore, this review will also highlight areas where T cell phenotypes require urgent characterisation.

Coronavirus disease 2019 has generated a rapidly evolving field of research, with the global scientific community striving for solutions to the current pandemic. Characterizing humoral responses towards SARS-CoV-2, as well as closely related strains, will help determine whether antibodies are central to infection control, and aid the design of therapeutics and vaccine candidates. This review outlines the major aspects of SARS-CoV-2-specific antibody research to date, with a focus on the various prophylactic and therapeutic uses of antibodies to alleviate disease in addition to the potential of cross-reactive therapies and the implications of long-term immunity.

COVID-19 was initially characterized as a disease primarily of the lungs, but it is becoming increasingly clear that the SARS-CoV2 virus is able to infect many organs and cause a broad pathological response. The primary infection site is likely to be a mucosal surface, mainly the lungs or the intestine, where epithelial cells can be infected with virus. Although it is clear that virus within the lungs can cause severe pathology, driven by an exaggerated immune response, infection within the intestine generally seems to cause minor or no symptoms. In this review, we compare the disease processes between the lungs and gastrointestinal tract, and what might drive these different responses. As the microbiome is a key part of mucosal barrier sites, we also consider the effect that microbial species may play on infection and the subsequent immune responses. Because of difficulties obtaining tissue samples, there are currently few studies focused on the local mucosal response rather than the systemic response, but understanding the local immune response will become increasingly important for understanding the mechanisms of disease in order to develop better treatments.

Epigenetic regulation plays a key role in the link between inflammation and cancer. Here we examine Mbd2, which mediates epigenetic transcriptional silencing by binding to methylated DNA. In separate studies the Mbd2 −/− mouse has been shown (1) to be resistant to intestinal tumourigenesis and (2) to have an enhanced inflammatory/immune response, observations that are inconsistent with the links between inflammation and cancer. To clarify its role in tumourigenesis and inflammation, we used constitutive and conditional models of Mbd2 deletion to explore its epithelial and non‐epithelial roles in the intestine. Using a conditional model, we found that suppression of intestinal tumourigenesis is due primarily to the absence of Mbd2 within the epithelia. Next, we demonstrated, using the DSS colitis model, that non‐epithelial roles of Mbd2 are key in preventing the transition from acute to tumour‐promoting chronic inflammation. Combining models revealed that prior to inflammation the altered Mbd2 −/− immune response plays a role in intestinal tumour suppression. However, following inflammation the intestine converts from tumour suppressive to tumour promoting. To summarise, in the intestine the normal function of Mbd2 is exploited by cancer cells to enable tumourigenesis, while in the immune system it plays a key role in preventing tumour‐enabling inflammation. Which role is dominant depends on the inflammation status of the intestine. As environmental interactions within the intestine can alter DNA methylation patterns, we propose that Mbd2 plays a key role in determining whether these interactions are anti‐ or pro‐tumourigenic and this makes it a useful new epigenetic model for inflammation‐associated carcinogenesis. © 2018 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Background The relationship between intestinal epithelial integrity and the development of intestinal disease is of increasing interest. A reduction in mucosal integrity has been associated with ulcerative colitis, Crohn’s disease and potentially could have links with colorectal cancer development. The Ussing chamber system can be utilised as a valuable tool for measuring gut integrity. Here we describe step-by-step methodology required to measure intestinal permeability of both mouse and human colonic tissue samples ex vivo, using the latest equipment and software. This system can be modified to accommodate other tissues. Methods An Ussing chamber was constructed and adapted to support both mouse and human tissue to measure intestinal permeability, using paracellular flux and electrical measurements. Two mouse models of intestinal inflammation (dextran sodium sulphate treatment and T regulatory cell depletion using C57BL/6-FoxP3DTR mice) were used to validate the system along with human colonic biopsy samples. Results Distinct regional differences in permeability were consistently identified within mouse and healthy human colon. In particular, mice showed increased permeability in the mid colonic region. In humans the left colon is more permeable than the right. Furthermore, inflammatory conditions induced chemically or due to autoimmunity reduced intestinal integrity, validating the use of the system. Conclusions The Ussing chamber has been used for many years to measure barrier function. However, a clear and informative methods paper describing the setup of modern equipment and step-by-step procedure to measure mouse and human intestinal permeability isn’t available. The Ussing chamber system methodology we describe provides such detail to guide investigation of gut integrity. Electronic supplementary material The online version of this article (10.1186/s12876-019-1002-4) contains supplementary material, which is available to authorized users.

Epigenetic regulation plays a key role in the link between inflammation and cancer. Here we examine Mbd2, which mediates epigenetic transcriptional silencing by binding to methylated DNA. In separate studies the Mbd2−/− mouse has been shown (1) to be resistant to intestinal tumourigenesis and (2) to have an enhanced inflammatory/immune response, observations that are inconsistent with the links between inflammation and cancer. To clarify its role in tumourigenesis and inflammation, we used constitutive and conditional models of Mbd2 deletion to explore its epithelial and non-epithelial roles in the intestine. Using a conditional model, we found that suppression of intestinal tumourigenesis is due primarily to the absence of Mbd2 within the epithelia. Next, we demonstrated, using the DSS colitis model, that non-epithelial roles of Mbd2 are key in preventing the transition from acute to tumour-promoting chronic inflammation. Combining models revealed that prior to inflammation the altered Mbd2−/− immune response plays a role in intestinal tumour suppression. However, following inflammation the intestine converts from tumour suppressive to tumour promoting. To summarise, in the intestine the normal function of Mbd2 is exploited by cancer cells to enable tumourigenesis, while in the immune system it plays a key role in preventing tumour-enabling inflammation. Which role is dominant depends on the inflammation status of the intestine. As environmental interactions within the intestine can alter DNA methylation patterns, we propose that Mbd2 plays a key role in determining whether these interactions are anti- or pro-tumourigenic and this makes it a useful new epigenetic model for inflammation-associated carcinogenesis.

Tertiary lymphoid structures (TLSs) display phenotypic and functional characteristics of secondary lymphoid organs, and often develop in tissues affected by chronic inflammation, as well as in certain inflammation-associated cancers where they are prognostic of improved patient survival. However, the mechanisms that govern the development of tumour-associated TLSs remain ill-defined. Here, we observed tumour-associated TLSs in a preclinical mouse model (gp130F/F) of gastric cancer, where tumourigenesis is dependent on hyperactive STAT3 signalling through the common IL-6 family signalling receptor, gp130. Gastric tumourigenesis was associated with the development of B and T cell-rich submucosal lymphoid aggregates, containing CD21+ cellular networks and high endothelial venules. Temporally, TLS formation coincided with the development of gastric adenomas and induction of homeostatic chemokines including Cxcl13, Ccl19 and Ccl21. Reflecting the requirement of gp130-driven STAT3 signalling for gastric tumourigenesis, submucosal TLS development was also STAT3-dependent, but independent of the cytokine IL-17 which has been linked with lymphoid neogenesis in chronic inflammation and autoimmunity. Interestingly, upregulated lymphoid chemokine expression and TLS formation were also observed in a chronic gastritis model induced by Helicobacter felis infection. Tumour-associated TLSs were also observed in patients with intestinal-type gastric cancer, and a gene signature linked with TLS development in gp130F/F mice was associated with advanced clinical disease, but was not prognostic of patient survival. Collectively, our in vivo data reveal that hyperactive gp130-STAT3 signalling closely links gastric tumourigenesis with lymphoid neogenesis, and while a TLS gene signature was associated with advanced gastric cancer in patients, it did not indicate a favourable prognosis.

The power of T cells for cancer treatment has been demonstrated by the success of co‐inhibitory receptor blockade and adoptive T‐cell immunotherapies. These treatments are highly successful for certain cancers, but are often personalized, expensive and associated with harmful side effects. Other T‐cell‐modulating drugs may provide additional means of improving immune responses to tumours without these disadvantages. Conventional chemotherapeutic drugs are traditionally used to target cancers directly; however, it is clear that some also have significant immune‐modulating effects that can be harnessed to target tumours. Cyclophosphamide is one such drug; used at lower doses than in mainstream chemotherapy, it can perturb immune homeostasis, tipping the balance towards generation of anti‐tumour T‐cell responses and control of cancer growth. This review discusses its growing reputation as an immune‐modulator whose multiple effects synergize with the microbiota to tip the balance towards tumour immunity offering widespread benefits as a safe, and relatively inexpensive component of cancer immunotherapy.

International audience; The inherent resistance of cancer stem cells (CSCs) to existing therapies has largely hampered the development of effective treatments for advanced malignancy. To help develop novel immunotherapy approaches that efficiently target CSCs, an experimental model allowing reliable distinction of CSCs and non-CSCs was set up to study their interaction with non-MHC-restricted γδ T cells and antigen-specific CD8 + T cells. Stable lines with characteristics of breast CSC-like cells were generated from ras-transformed human mammary epithelial (HMLER) cells as confirmed by their CD44 hi CD24 lo GD2 + phenotype, their mesenchymal morphology in culture and their capacity to form mammospheres under non-adherent conditions, as well as their potent tumorigenicity, self-renewal and differentiation in xenografted mice. The resistance of CSC-like cells to γδ T cells could be overcome by inhibition of farnesyl pyrophosphate synthase (FPPS) through pretreatment with zoledronate or with FPPS-targeting short hairpin RNA. γδ T cells induced upregulation of MHC class I and CD54/ICAM-1 on CSC-like cells and thereby increased the susceptibility to antigen-specific killing by CD8 + T cells. Alternatively, γδ T-cell responses could be specifically directed against CSC-like cells using the humanised anti-GD2 monoclonal antibody hu14.18K322A. Our findings identify a powerful synergism between MHC-restricted and non-MHC-restricted T cells in the eradication of cancer cells including breast CSCs. Our research suggests that novel immunotherapies may benefit from a two-pronged approach combining γδ T-cell and CD8 + T-cell targeting strategies that triggers effective innate-like and tumour-specific adaptive responses.

Although elevated CD4+Foxp3+ regulatory T cell (Treg) frequencies within tumors are well documented, the functional and phenotypic characteristics of CD4+Foxp3+ and CD4+Foxp3− T cell subsets from matched blood, healthy colon, and colorectal cancer require in-depth investigation. Flow cytometry revealed that the majority of intratumoral CD4+Foxp3+ T cells (Tregs) were Helios+ and expressed higher levels of cytotoxic T-lymphocyte antigen 4 (CTLA-4) and CD39 than Tregs from colon and blood. Moreover, ~30% of intratumoral CD4+Foxp3− T cells expressed markers associated with regulatory functions, including latency-associated peptide (LAP), lymphocyte activation gene-3 (LAG-3), and CD25. This unique population of cells produced interleukin-10 (IL-10) and transforming growth factor-β (TGF-β), and was ~50-fold more suppressive than Foxp3+ Tregs. Thus, intratumoral Tregs are diverse, posing multiple obstacles to immunotherapeutic intervention in colorectal malignancies.

Foxp3+ regulatory T cells (Tregs) are often highly enriched within the tumor-infiltrating T cell pool. Using a well-characterised model of carcinogen-induced fibrosarcomas we show that the enriched tumor-infiltrating Treg population comprises largely of CXCR3+ T-bet+ 'TH1-like' Tregs which are thymus-derived Helios+ cells. Whilst IL-2 maintains homeostatic ratios of Tregs in lymphoid organs, we found that the perturbation in Treg frequencies in tumors is IL-2 independent. Moreover, we show that the TH1 phenotype of tumor-infiltrating Tregs is dispensable for their ability to influence tumor progression. We did however find that unlike Tconvs, the majority of intra-tumoral Tregs express the activation markers CD69, CD25, ICOS, CD103 and CTLA4 and are significantly more proliferative than Tconvs. Moreover, we have found that CD69+ Tregs are more suppressive than their CD69- counterparts. Collectively, these data indicate superior activation of Tregs in the tumor microenvironment, promoting their suppressive ability and selective proliferation at this site.

Liver disease is an increasing global health burden. The final sequalae of cirrhosis, liver failure and hepatocellular carcinoma are often the result of inflammation driven by intrahepatic lymphocytes. Accurate assessment of organ-specific diseases ideally employs tissue sampling though this is rarely performed. Here we report our experiences of utilising repeated fine needle aspirations (FNAs) to assess liver-derived leukocytes. In 88 patient samples, we obtained a mean of 36,959 lymphocytes from each FNA-derived biopsy (SD 22,319 cells, range 5034–91,242 cells) measured by flow cytometry. This quick technique required minimal analgesia compared to liver biopsy (p = 0.03); was well tolerated and safe, and hence repeated sampling up to 3 times within a week was feasible. We detail the technique to rapidly derive a single cell suspension suitable for multiparameter flow cytometry analysis. Finally we illustrate the importance of organ-derived sampling by showing that natural killer (NK) cells from FNA samples have a markedly altered phenotype compared to those assessed in peripheral blood. In combination these data validate FNA as a powerful and well-tolerated method of sampling intrahepatic lymphocytes to study the immunology of acute and chronic liver diseases.

Current dogma suggests that tumor-reactive IFN-γ–producing (TH1-type) T-cells are beneficial to patient outcome; however, the clinical consequence of these responses with respect to long-term prognosis in colorectal cancer (CRC) is not understood. Here, we compared the utility of preoperative, peripheral blood–derived IFN-γ+ T-cell responses specific to carcinoembryonic antigen (CEA), 5T4, or control antigens (n = 64) with tumor staging and clinical details (n = 87) in predicting five-year outcome of CRC patients who underwent resection with curative intent. Although disease recurrence was more likely in patients with stage III tumors, the presence of preoperative, CEA-specific IFN-γ–producing T-cells identified patients at a statistically significantly greater risk of tumor recurrence following surgical resection, irrespective of tumor stage (odds ratio = 5.00, 95% confidence interval = 1.96 to 12.77, two-sided P

Prolonged patient survival after surgical resection, is associated with a higher cytotoxic and memory T cell density within colorectal cancers (CRC). High endothelial venules (HEVs) are specialized blood vessels present in secondary lymphoid organs (SLO) that allow ingress of naïve and central memory T cells from the blood. It has been proposed that HEVs in tumors might serve as a similar route of entry for lymphocytes into the tumor and result in an improved prognosis. The present study aimed to characterize HEVs and their microenvironment in resected tumors from colorectal cancer patients (n = 62). We observed HEVs in association with lymphoid aggregates in 49 out of 62 patients. However, these HEV+ lymphoid aggregates were largely at the invasive margin of the tumor and although there was an association with lymphocytes and HEVs at the invasive margin (p = 0.002) there was only a very weak association with tumor infiltrating lymphocytes. Indeed, lymphoid aggregates were associated with more advanced disease (Dukes’ stage C) and did not indicate a favorable prognosis.

Background: Cells undergoing apoptosis are known to modulate their tissue microenvironments. By acting on phagocytes, notably macrophages, apoptotic cells inhibit immunological and inflammatory responses and promote trophic signaling pathways. Paradoxically, because of their potential to cause death of tumor cells and thereby militate against malignant disease progression, both apoptosis and tumor-associated macrophages (TAMs) are often associated with poor prognosis in cancer. We hypothesized that, in progression of malignant disease, constitutive loss of a fraction of the tumor cell population through apoptosis could yield tumor-promoting effects. Results: Here, we demonstrate that apoptotic tumor cells promote coordinated tumor growth, angiogenesis, and accumulation of TAMs in aggressive B cell lymphomas. Through unbiased "in situ transcriptomics" analysis-gene expression profiling of laser-captured TAMs to establish their activation signature insitu-we show that these cells are activated tosignal via multiple tumor-promoting reparatory, trophic, angiogenic, tissue remodeling, and anti-inflammatory pathways. Our results also suggest that apoptotic lymphoma cells help drive this signature. Furthermore, we demonstrate that, upon induction of apoptosis, lymphoma cells not only activate expression of the tumor-promoting matrix metalloproteinases MMP2 and MMP12 in macrophages but also express and process these MMPs directly. Finally, using a model of malignant melanoma, we show that the oncogenic potential of apoptotic tumor cells extends beyond lymphoma. Conclusions: In addition to its profound tumor-suppressive role, apoptosis can potentiate cancer progression. These results have important implications for understanding the fundamental biology of cell death, its roles in malignant disease, and the broader consequences of apoptosis-inducing anti-cancer therapy. Apoptosis and tumor-associated macrophages (TAMs) are often associated with poor prognosis in cancer. Ford etal. demonstrate apoptotic lymphoma cells can promote tumor growth, angiogenesis, TAM accumulation, and TAM activation to potentiate cancer progression. These results have important implications for apoptosis-inducing anti-cancer therapies.

The tumor microenvironment comprises newly formed blood and lymphatic vessels which shape the influx, retention and departure of lymphocytes within the tumor mass. Thus, by influencing the intratumoral composition of lymphocytes, these vessels affect the manner in which the adaptive immune system responds to the tumor, either promoting or impairing effective antitumor immunity. In our study, we utilized a mouse model of carcinogen-induced fibrosarcoma to examine the composition of tumor-infiltrating lymphocytes during tumor progression. In particular, we sought to determine whether CD4+Foxp3+ regulatory T cells (Tregs) became enriched during tumor progression thereby contributing to tumor-driven immunosuppression. This was not the case as the proportion of Tregs and effector CD4+ T cells actually declined within the tumor owing to the unexpected accumulation of naïve T cells. However, we found no evidence for antigen-driven migration of these T cells or for their participation in an antitumor immune response. Our data support the notion that lymphocytes can enter tumors via aberrantly formed blood and lymphatic vessels. Such findings suggest that targeting both the tumor vasculature and lymphatics will alter the balance of lymphocyte subpopulations that enter the tumor mass. A consideration of this aspect of tumor immunology may be critical to the success of solid cancer immunotherapies.

Balancing the generation of immune responses capable of controlling virus replication with those causing immunopathology is critical for the survival of the host and resolution of influenza-induced inflammation. Based on the capacity of interleukin-6 (IL-6) to govern both optimal T-cell responses and inflammatory resolution, we hypothesised that IL-6 plays an important role in maintaining this balance. Comparison of innate and adaptive immune responses in influenza-infected wild-type control and IL-6-deficient mice revealed striking differences in virus clearance, lung immunopathology and generation of heterosubtypic immunity. Mice lacking IL-6 displayed a profound defect in their ability to mount an anti-viral T-cell response. Failure to adequately control virus was further associated with an enhanced infiltration of inflammatory monocytes into the lung and an elevated production of the pro-inflammatory cytokines, IFN-α and TNF-α. These events were associated with severe lung damage, characterised by profound vascular leakage and death. Our data highlight an essential role for IL-6 in orchestrating anti-viral immunity through an ability to limit inflammation, promote protective adaptive immune responses and prevent fatal immunopathology.

Decline of cell-mediated immunity is often attributed to decaying T-cell numbers and their distribution in peripheral organs. This study examined the hypothesis that qualitative as well as quantitative changes contribute to the declining efficacy of CD8(+) T-cell memory. Using a model of influenza virus infection, where loss of protective CD8(+) T-cell immunity was observed 6 months postinfection, we found no decline in antigen-specific T-cell numbers or migration to the site of secondary infection. There was, however, a large reduction in antigen-specific CD8(+) T-cell degranulation, cytokine secretion, and polyfunctionality. A profound loss of high-avidity T cells over time indicated that failure to confer protective immunity resulted from the inferior functional capacity of remaining low avidity cells. These data imply that high-avidity central memory T cells wane with declining antigen levels, leaving lower avidity T cells with reduced functional capabilities.

An enormous body of work supports a role for CD4+ CD25+ regulatory cells (Tregs) in shaping the immune response to tumours. Indeed, there is evidence that the cells impede effective tumour immunosurveillance, inhibit vaccine-induced antitumour immune responses and promote tumour progression. Studies exploring the impact of Tregs on tumour development are discussed in the context of manipulating this T-cell population for the purpose of cancer immunotherapy.

CD59 blocks formation of the membrane attack complex of complement by inhibiting binding of C9 to the C5b-8 complex. To investigate a role for CD59 in promoting T cell responses, we compared T cell activation in CD59a-deficient (Cd59a−/−) and wild-type (WT) mice after in vitro stimulation and after infection with recombinant vaccinia virus. Virus-specific CD4+ T cell responses were significantly enhanced in Cd59a−/− mice compared to WT mice. Similarly, Cd59a−/− T cells responded more vigorously to in vitro stimulation with CD3-specific antibodies compared to WT mice. This effect of CD59a on T cell proliferation was found to be complement-independent. Collectively, these results demonstrate that CD59a down-modulates CD4+ T cell activity in vitro and in vivo, thereby revealing another link between complement regulators and T cell activation.

Liver disease is an increasing global health burden. The final sequalae of cirrhosis, liver failure and hepatocellular carcinoma are often the result of inflammation driven by intrahepatic lymphocytes. Accurate assessment of organ-specific diseases ideally employs tissue sampling though this is rarely performed. Here we report our experiences of utilising repeated fine needle aspirations (FNAs) to assess liver-derived leukocytes. In 88 patient samples, we obtained a mean of 36,959 lymphocytes from each FNA-derived biopsy (SD 22,319 cells, range 5034–91,242 cells) measured by flow cytometry. This quick technique required minimal analgesia compared to liver biopsy (p=0.03); was well tolerated and safe, and hence repeated sampling up to 3 times within a week was feasible. We detail the technique to rapidly derive a single cell suspension suitable for multiparameter flow cytometry analysis. Finally we illustrate the importance of organ-derived sampling by showing that natural killer (NK) cells from FNA samples have a markedly altered phenotype compared to those assessed in peripheral blood. In combination these data validate FNA as a powerful and well-tolerated method of sampling intrahepatic lymphocytes to study the immunology of acute and chronic liver diseases.

Accurate assessment of SARS-CoV-2 immunity in the population is critical to evaluating vaccine efficacy and devising public health policies. Whilst the exact nature of effective immunity remains incompletely defined, SARS-CoV-2-specific T cell responses are a critical feature of the immune response that will likely form a key correlate of protection against COVID-19. Here, we developed and optimised a high-throughput whole blood-based assay to determine the T cell response associated with prior SARS-CoV-2 infection and/or vaccination amongst 156 healthy donors and 67 cancer patients. Following overnight in vitro stimulation with SARS-CoV-2-specific peptides, blood plasma samples were harvested and analysed for TH1-type effector cytokines (IFN-γ and IL-2). Amongst healthy donors, highly significant differential IFN-γ+/IL-2+ SARS-CoV-2-specific T cell responses were seen amongst vaccinated or previously infected COVID-19-positive individuals in comparison to unknown/naïve individuals (P < 0.0001). IL-2 production from T cells in response to SARS-CoV-2 derived antigens was a highly predictive diagnostic assay (P < 0.0001; 96.0% sensitivity, 93.9% specificity); measurement of IFN-γ+ SARS-CoV-2 specific T cell responses was equally effective at identifying asymptomatic (antibody and T cell positive) participants. A single dose of COVID-19 vaccine induced IFN-γ and/or IL-2 SARS-CoV-2-specific T cell responses in 28/29 (96.6%) of healthy donors, reducing significantly to 27/56 (48.2%) when measured in cancer patients (P = 0.0003). Overall, this cost-effective standardisable test ensures accurate and comparable assessments of SARS-CoV-2-specific T cell responses amenable to widespread population immunity testing.