Prime and pull of T cell responses against cancer-exogenous antigens is effective against CPI-resistant tumors.

Neoantigen (neoAg)-based cancer vaccines expand preexisting antitumor immunity and elicit novel cancer-specific T cells. However, at odds with prophylactic vaccines, therapeutic antitumor immunity must be induced when the tumor is present and has already established an immunosuppressive environment capable of rapidly impairing the function of anticancer neoAg T cells, thereby leading to lack of efficacy. To overcome tumor-induced immunosuppression, we first vaccinated mice bearing immune checkpoint inhibitor (CPI)-resistant tumors with an adenovirus vector encoding a set of potent cancer-exogenous CD8 and CD4 T cell epitopes (Ad-CAP1), and then "taught" cancer cells to express the same epitopes by using a tumor-retargeted herpesvirus vector (THV-CAP1). Potent CD8 effector T lymphocytes were elicited by Ad-CAP1, and subsequent THV-CAP1 delivery led to a significant delay in tumor growth and even cure.

Development of a Potency Assay for Nous-209, a Multivalent Neoantigens-Based Genetic Cancer Vaccine.

Quality control testing of vaccines, including potency assessment, is critical to ensure equivalence of clinical lots. We developed a potency assay to support the clinical advancement of Nous-209, a cancer vaccine based on heterologous prime/boost administration of two multivalent viral vector products: GAd-209 and MVA-209. These consist of a mix of four Adeno (Great Ape Adenovirus; GAd) and four Modified Vaccinia Ankara (MVA) vectors respectively, each containing a different transgene encoding a synthetic polypeptide composed of antigenic peptide fragments joined one after the other. The potency assay employs quantitative Reverse Transcription PCR (RT-Q-PCR) to quantitatively measure the transcripts from the four transgenes encoded by each product in in vitro infected cells, enabling simultaneous detection. Results showcase the assay's robustness and biological relevance, as it effectively detects potency loss in one component of the mixture comparably to in vivo immunogenicity testing. This report details the assay's setup and validation, offering valuable insights for the clinical development of similar genetic vaccines, particularly those encoding synthetic polypeptides.

Tumor Burden Dictates the Neoantigen Features Required to Generate an Effective Cancer Vaccine.

Tumor neoantigens (nAg) represent a promising target for cancer immunotherapy. The identification of nAgs that can generate T-cell responses and have therapeutic activity has been challenging. Here, we sought to unravel the features of nAgs required to induce tumor rejection. We selected clinically validated Great Ape-derived adenoviral vectors (GAd) as a nAg delivery system for differing numbers and combinations of nAgs. We assessed their immunogenicity and efficacy in murine models of low to high disease burden, comparing multi-epitope versus mono-epitope vaccines. We demonstrated that the breadth of immune response is critical for vaccine efficacy and having multiple immunogenic nAgs encoded in a single vaccine improves efficacy. The contribution of each single neoantigen was examined, leading to the identification of 2 nAgs able to induce CD8+ T cell-mediated tumor rejection. They were both active as individual nAgs in a setting of prophylactic vaccination, although to different extents. However, the efficacy of these single nAgs was lost in a setting of therapeutic vaccination in tumor-bearing mice. The presence of CD4+ T-cell help restored the efficacy for only the most expressed of the two nAgs, demonstrating a key role for CD4+ T cells in sustaining CD8+ T-cell responses and the necessity of an efficient recognition of the targeted epitopes on cancer cells by CD8+ T cells for an effective antitumor response. This study provides insight into understanding the determinants of nAgs relevant for effective treatment and highlights features that could contribute to more effective antitumor vaccines. See related Spotlight by Slingluff Jr, p. 382.

Adenovirus Encoded Adjuvant (AdEnA) anti-CTLA-4, a novel strategy to improve Adenovirus based vaccines against infectious diseases and cancer.

Introduction: Virus vectored genetic vaccines (Vvgv) represent a promising approach for eliciting immune protection against infectious diseases and cancer. However, at variance with classical vaccines to date, no adjuvant has been combined with clinically approved genetic vaccines, possibly due to the detrimental effect of the adjuvant-induced innate response on the expression driven by the genetic vaccine vector. We reasoned that a potential novel approach to develop adjuvants for genetic vaccines would be to "synchronize" in time and space the activity of the adjuvant with that of the vaccine. Methods: To this aim, we generated an Adenovirus vector encoding a murine anti-CTLA-4 monoclonal antibody (Ad-9D9) as a genetic adjuvant for Adenovirus based vaccines. Results: The co-delivery of Ad-9D9 with an Adeno-based COVID-19 vaccine encoding the Spike protein resulted in stronger cellular and humoral immune responses. In contrast, only a modest adjuvant effect was achieved when combining the vaccine with the same anti-CTLA-4 in its proteinaceous form. Importantly, the administration of the adjuvant vector at different sites of the vaccine vector abrogates the immunostimulatory effect. We showed that the adjuvant activity of Ad-α-CTLA-4 is independent from the vaccine antigen as it improved the immune response and efficacy of an Adenovirus based polyepitope vaccine encoding tumor neoantigens. Discussion: Our study demonstrated that the combination of Adenovirus Encoded Adjuvant (AdEnA) with an Adeno-encoded antigen vaccine enhances immune responses to viral and tumor antigens, representing a potent approach to develop more effective genetic vaccines.

Vector Aided Microenvironment programming (VAMP): reprogramming the TME with MVA virus expressing IL-12 for effective antitumor activity.

BACKGROUND: Tumor microenvironment (TME) represents a critical hurdle in cancer immunotherapy, given its ability to suppress antitumor immunity. Several efforts are made to overcome this hostile TME with the development of new therapeutic strategies modifying TME to boost antitumor immunity. Among these, cytokine-based approaches have been pursued for their known immunomodulatory effects on different cell populations within the TME. IL-12 is a potent pro-inflammatory cytokine that demonstrates striking immune activation and tumor control but causes severe adverse effects when systemically administered. Thus, local administration is considered a potential strategy to achieve high cytokine concentrations at the tumor site while sparing systemic adverse effects. METHODS: Modified Vaccinia Ankara (MVA) vector is a potent inducer of pro-inflammatory response. Here, we cloned IL-12 into the genome of MVA for intratumoral immunotherapy, combining the immunomodulatory properties of both the vector and the cargo. The antitumor activity of MVA-IL-12 and its effect on TME reprogramming were investigated in preclinical tumor models. RNA sequencing (RNA-Seq) analysis was performed to assess changes in the TME in treated and distal tumors and the effect on the intratumoral T-cell receptor repertoire. RESULTS: Intratumoral injection of MVA-IL-12 resulted in strong antitumor activity with the complete remission of established tumors in multiple murine models, including those resistant to checkpoint inhibitors. The therapeutic activity of MVA-IL-12 was associated with very low levels of circulating cytokine. Effective TME reprogramming was demonstrated on treatment, with the reduction of immunosuppressive M2 macrophages while increasing pro-inflammatory M1, and recruitment of dendritic cells. TME switch from immunosuppressive into immunostimulatory environment allowed for CD8 T cells priming and expansion leading to tumor attack. CONCLUSIONS: Intratumoral administration of MVA-IL-12 turns immunologically 'cold' tumors 'hot' and overcomes resistance to programmed cell death protein-1 blockade.

VENUS, a Novel Selection Approach to Improve the Accuracy of Neoantigens' Prediction.

Neoantigens are tumor-specific antigens able to induce T-cell responses, generated by mutations in protein-coding regions of expressed genes. Previous studies demonstrated that only a limited subset of mutations generates neoantigens in microsatellite stable tumors. We developed a method, called VENUS (Vaccine-Encoded Neoantigens Unrestricted Selection), to prioritize mutated peptides with high potential to be neoantigens. Our method assigns to each mutation a weighted score that combines the mutation allelic frequency, the abundance of the transcript coding for the mutation, and the likelihood to bind the patient's class-I major histocompatibility complex alleles. By ranking mutated peptides encoded by mutations detected in nine cancer patients, VENUS was able to select in the top 60 ranked peptides, the 95% of neoantigens experimentally validated including both CD8 and CD4 T cell specificities. VENUS was evaluated in a murine model in the context of vaccination with an adeno vector encoding the top ranked mutations prioritized in the MC38 cell line. Efficacy studies demonstrated anti tumoral activity of the vaccine when used in combination with checkpoint inhibitors. The results obtained highlight the importance of a combined scoring system taking into account multiple features of each tumor mutation to improve the accuracy of neoantigen prediction.

SARS CoV2 infection _The longevity study perspectives.

Like other infectious diseases, COVID-19 shows a clinical outcome enormously variable, ranging from asymptomatic to lethal. In Italy, like in other countries, old male individuals, with one or more comorbidity, are the most susceptible group, and show, consequently, the highest mortality, and morbidity, including lethal respiratory distress syndrome, as the most common complication. In addition, another extraordinary peculiarity, that is a surprising resistance to COVID-19, characterizes some Italian nonagenarians/centenarians. Despite having the typical COVID-19 signs and/or symptoms, such exceptional individuals show a surprising tendency to recover from illness and complications. On the other hand, long-lived people have an optimal performance of immune system related to an overexpression of anti-inflammatory variants in immune/inflammatory genes, as demonstrated by our and other groups. Consequently, we suggest long-lived people as an optimal model for detecting genetic profiles associated with the susceptibility and/or protection to COVID-19, to utilize as potential pharmacological targets for preventing or reducing viral infection in more vulnerable individuals.

A Typical Immune T/B Subset Profile Characterizes Bicuspid Aortic Valve: In an Old Status?

Bicuspid valve disease is associated with the development of thoracic aortic aneurysm. The molecular mechanisms underlying this association still need to be clarified. Here, we evaluated the circulating levels of T and B lymphocyte subsets associated with the development of vascular diseases in patients with bicuspid aortic valve or tricuspid aortic valve with and without thoracic aortic aneurysm. We unveiled that the circulating levels of the MAIT, CD4+IL-17A+, and NKT T cell subsets were significantly reduced in bicuspid valve disease cases, when compared to tricuspid aortic valve cases in either the presence or the absence of thoracic aortic aneurysm. Among patients with tricuspid aortic valve, these cells were higher in those also affected by thoracic aortic aneurysm. Similar data were obtained by examining CD19+ B cells, naïve B cells (IgD+CD27-), memory unswitched B cells (IgD+CD27+), memory switched B cells (IgD-CD27+), and double-negative B cells (DN) (IgD-CD27-). These cells resulted to be lower in subjects with bicuspid valve disease with respect to patients with tricuspid aortic valve. In whole, our data indicate that patients with bicuspid valve disease show a quantitative reduction of T and B lymphocyte cell subsets. Future studies are encouraged to understand the molecular mechanisms underlying this observation and its pathophysiological significance.

The complex alteration in the network of IL-17-type cytokines in patients with hereditary angioedema.

Hereditary angioedema (HAE) is a rare autosomic-dominant disorder characterized by a deficiency of C1 esterase inhibitor which causes episodic swellings of subcutaneous tissues, bowel walls and upper airways that are disabling and potentially life-threatening. We evaluated n = 17 patients with confirmed HAE diagnosis during attack and remission state and n = 19 healthy subjects. The samples were tested for a panel of IL (Interleukin)-17-type cytokines (IL-1ß, IL-6, IL-10, granulocyte-macrophage colony stimulating factor (GM-CSF), IL-17, IL-21, IL-22, IL-23) and transforming growth factor-beta (TGF-ß) subtypes. Data indicate that there are variations of cytokine levels in HAE subjects comparing the condition during the crisis respect to the value in the remission phase, in particular type 17 signature cytokines are increased, whereas IL-23 is unmodified and TGF-ß3 is significantly reduced. When comparing healthy and HAE subjects in the remission state, we found a significant difference for IL-17, GM-CSF, IL-21, TGF-ß1 and TGF-ß2 cytokines. These results confirm and extend our previous findings indicating that in HAE there is operating an inflammatory activation process, which involves also T helper 17 (Th17) cytokines and TGF-ß isoforms, associated with localized angioedema attacks and characterized by elevated bradykinin levels.

From lymphopoiesis to plasma cells differentiation, the age-related modifications of B cell compartment are influenced by "inflamm-ageing".

Ageing is a complex process characterized by a general decline in physiological functions with increasing morbidity and mortality. The most important aspect of ageing is the chronic inflammatory status, named "inflamm-ageing", strictly associated with the deterioration of the immune function, termed "immunosenescence". Both are causes of increased susceptibility of elderly to infectious diseases, cancer, dementia, cardiovascular diseases and autoimmunity, and of a decreased response to vaccination. It has been widely demonstrated that ageing has a strong impact on the remodelling of the B cell branch of immune system. The first evident effect is the significant decrease in circulating B cells, primarily due to the reduction of new B cell coming from bone marrow (BM) progenitors, as inflammation directly impacts on B lymphopoiesis. Besides, in aged individuals, there is a shift from naïve to memory immunoglobulins production, accompanied by the impaired ability to produce high affinity protective antibodies against newly encountered antigens. This is accompanied by the increase of expanded clones of B cells, which correlates with poor health status. Age-related modifications also occur in naïve/memory B cells subsets. Indeed, in the elderly, there is a reduction of naïve B cells, accompanied by the expansion of memory B cells that show a senescence-associated phenotype. Finally, elderly show the impaired ability of memory B cells to differentiate into plasma cells. It can be concluded that inflammation is the leading cause of the age-related impairment of B cell compartment, which play certainly a key role in the development of age-related diseases. This makes study of B cells in the aged an important tool for monitoring immunosenescence, chronic inflammatory disorders and the effectiveness of vaccines or pharmacological therapies.

Bone marrow B lymphocytes in multiple myeloma and MGUS: Focus on distribution of naïve cells and memory subsets.

BACKGROUND/AIMS: Multiple myeloma (MM) is caused by proliferation of clonal plasma cells (cPCs) in bone marrow (BM), associated with numerical and functional defects in immune subsets. An impairment of B cell compartment is involved in onset/progression of the disease. METHODS: By flow cytometry, we studied distribution of naïve/transitional (IgD(+)CD27(-)), memory unswitched (IgD(+)CD27(+)), memory switched (IgD(-)CD27(+)) and double negative (DN) (IgD(-)CD27(-)) B lymphocytes in BM of control subjects, and responding and relapsing patients. RESULTS: We observed an increased percentage of IgD(+)CD27(+) B cells in healthy controls vs responding patients (p<0.05). Treated non complete responders exhibited an expanded DN compartment vs stringent complete responders (p=0.011); in turn IgD(+)CD27(-) subpopulation was larger in stringent complete responders vs other responding patients (p=0.006). None of the studied B cell subsets showed clonal restriction. Correlation analysis revealed negative correlations between naïve/transitional and DN B cells in all groups, except in newly diagnosed subjects. CONCLUSIONS: This may be considered a feasible start point to explore the importance of B cells in the immunosuppressive MM BM microenvironment, correlating these findings with immunosenescence and therapy related increased risk of infection. Moreover, we propose a possible role of naïve/transitional and DN B cells as predictive markers in treated patients.

Correlation between CD117+ myeloma plasma cells and hematopoietic progenitor cells in different categories of patients.

BACKGROUND: Multiple myeloma (MM) is a neoplastic disorder of plasma cells interesting mainly the elderly. MM remains an incurable disease, mostly because of the strong interplay between clonal plasma cells (cPCs) and bone marrow (BM) microenvironment. Multiparameter flow cytometry (MFC) allows the simultaneous study of the cPC immunophenotype and alterations involving other cells in BM, but rarely these data are interpreted as connected. One exception to this habit are previous studies about relationship between CD117 cPC positivity and hematopoietic progenitor cell (HPC) distribution in newly diagnosed patients. Thus we were interested in verifying the distribution of BM CD34+ HPCs in healthy controls, and monoclonal gammopathy of undetermined significance (MGUS) patients and various categories of responding/relapsing MM subjects divided according to CD117 positivity. RESULTS: Our data completely agree with precedent reports as regards untreated patients. In the group with progression of disease, CD117- patients exhibited a lower CD34 + CD19-/CD34 + CD19+ ratio vs CD117+ subjects. Among CD117- cases, newly diagnosed patients exhibited differences in distribution of HPCs vs responding myeloma subjects and patients with progressive disease. These differences reached statistical significance comparing CD117- newly diagnosed with CD117- responding cases, as reflected by CD34 + CD19-/CD34 + CD19+ ratio. In turn, no differences emerged comparing CD117+ treated and untreated patients. CONCLUSIONS: We demonstrate that administration of treatment and depth of reached response/presence of relapse imply a distinct regulation in distribution of CD34+ HPC subsets in CD117- and CD117+ patients. These differences become evident comparing untreated and treated CD117- patients, but they are impossible to detect in CD117+ cases.

Old and new immunophenotypic markers in multiple myeloma for discrimination of responding and relapsing patients: The importance of "normal" residual plasma cell analysis.

BACKGROUND: Multiple myeloma is an incurable disease characterized by proliferation of clonal malignant plasma cells (CPCs), which can be immunophenotypically distinguished from polyclonal plasma cells (PPCs) by multiparameter flow cytometry (MFC). The utility of PPCs analysis in detecting prognostic and predictive information is still a matter of debate. METHODS: we tested the ability of 11 MFC markers in detecting differences in the immunophenotype of CPCs and PPCs among patients in various disease stages; we verified if these markers could be associated with disease stage/response to therapy despite the role of clinical parameters. RESULTS: significant changes in the expression of markers occurred both in CPCs and PPCs. CD58 on PPCs of responding patients was downregulated compared with PPC of relapsing group. Fraction of CD200 expressing PCs was lower in control subjects than in PPCs from MGUS and myeloma groups. CD11a levels of expression on both CPCs and PPCs showed an upregulation in newly diagnosed and relapsing patients versus PCs of controls; CD20 was less expressed on control PCs than on MGUS CPCs and PPCs. CD49d revealed to be advantageous in discrimination of PPCs from CPCs. In our multiple regression model, CD19 and CD49d on CPCs, and CD45, CD58 and CD56 on PPCs maintained their association with groups of patients independently of other prognostic variables. CONCLUSIONS: we provide a feasible start point to put in order ranges of expression on PPCs in healthy and myeloma subjects; we propose a new approach based on PPC analysis to monitor the stages of the disease.

Double negative (IgG+IgD-CD27-) B cells are increased in a cohort of moderate-severe Alzheimer's disease patients and show a pro-inflammatory trafficking receptor phenotype.

Alzheimer's disease (AD) is a progressive, irreversible, and debilitating disease for which no effective preventive or disease modifying therapies or treatments have so far been detected. The crucial step in AD pathogenesis is the production of amyloid-ß42 peptide, which causes chronic inflammation. Activated cells in the central nervous system (CNS) produce pro-inflammatory mediators that lead to the recruitment of myeloid or lymphocytic cells. As a consequence, the communication between the CNS and peripheral blood of AD subjects could influence the lymphocyte distribution and/or the expression of phenotypic markers. In the present paper, we show a significant decrease in total CD19+ B lymphocytes and a remodeling of the B cell subpopulations in moderate-severe AD patients, compared with their coeval healthy controls and mild AD subjects. In particular, we report a significant reduction in naïve B cells (IgD+CD27-) and a simultaneous increase in double negative (DN, IgD-CD27-) memory B lymphocytes. We have also evaluated the expression of the pro-inflammatory chemokine receptors CCR6 and CCR7 in total and naïve/memory B cells from mild and moderate-severe AD patients, with the aim to detect a possible relationship between the trafficking profile and the stage of the disease. Our results demonstrate that both the amount and the trafficking profile of B cells are related to the severity of AD. The results discussed in this paper suggest a well-selected antibody panel should be used as an additional test for the identification of early AD.

Double negative (CD19+IgG+IgD-CD27-) B lymphocytes: a new insight from telomerase in healthy elderly, in centenarian offspring and in Alzheimer's disease patients.

Immunosenescence is characterized by the impairment of humoral immunity with changes in the memory/naive B cell compartment. In particular we have previously reported the percentage increase of a Memory IgD(-)CD27(-) (Double Negative, DN) B cell population in aged people. In this study, we have further characterized DN B cells with the aim to better understand their contribution to immunosenescence. As DN B cells show a poor ability to proliferate in vitro, we have evaluated the expression of the inhibitory receptors CD307d and CD22 on these cells from young and old individuals. In addition we have evaluated the ability to activate DN B cells by the simultaneous use of innate (CpG) and adaptive (α-Ig/CD40) ligands. Our data demonstrate that the refractoriness to proliferate of DN B cells does not depend on the expression of inhibitory receptors, but it is due to the kind of stimulation. Indeed, when DN B cells are stimulated engaging both BCR and TLR9, they become able to proliferate and reactivate the telomerase enzyme. In the present study, we have also compared the telomerase activity in a group of people genetically advantaged for longevity as centenarian offspring (CO) and in a group of moderate-severe Alzheimer's disease (AD) patients, who represent a model of unsuccessful aging. Our study suggests that telomerase reactivation of DN B cells, as well as their number and ability in activating, depend essentially by the biological age of the subjects studied, so the evaluation of DN B cells might allow to gain insight to healthy and unsuccessful aging.

Role of TGF-ß pathway polymorphisms in sporadic thoracic aortic aneurysm: rs900 TGF-ß2 is a marker of differential gender susceptibility.

Thoracic aortic aneurysm (TAA) is a progressive disorder involving gradual dilation of ascending and/or descending thoracic aorta with dissection or rupture as complications. It occurs as sporadic or defined syndromes/familial forms.Genetic, molecular and cellular mechanims of sporadic TAA forms are poorly characterized and known. Thus, our interest has been focused on investigating the role of genetic variants of transforming growth factor-ß (TGF-ß) pathways in TAA risk. On the other hand, no data on the role of genetic variants of TGF-ß pathway in sporadic TAA exist until now. In addition, other cytokines, including IL-10, orchestrate TAA pathophysiology. Their balance determines the ultimate fate of the aortic wall as healing atherosclerosis or aneurysm formation. Thus, in this paper it was analyzed the role of ten polymorphisms of genes encoding TGF-ß isoforms and receptors, and IL-10 in sporadic TAA. Our study included cases affected by sporadic TAA and two control groups. The most relevant finding obtained allows us to propose that rs900 TGF-ß2 SNP is associated with sporadic TAA in women. This might open new perspectives for the analysis of sporadic TAA susceptibility factors and prevention.

Trafficking phenotype and production of granzyme B by double negative B cells (IgG(+)IgD(-)CD27(-)) in the elderly.

The impairment of humoral immune response in elderly humans has been extensively demonstrated. We have reported the increase of memory B cells (IgG(+)IgD(-)CD27(-), double negative, DN) population in the elderly, in which there is also a typical inflammatory micro-environment. In order to evaluate whether this pro-inflammatory status could influence the trafficking phenotype of naïve/memory B cells, we have assessed the expression of CCR7, CCR6, CXCR3, CXCR4, CXCR5 and CD62L on naïve/memory B cell subpopulations in young and elderly subjects. Moreover, the combination of pro-inflammatory interleukin-21 (IL-21) and B cell receptor (BCR) stimulation enables B cells to produce and secrete granzyme B (GrB), which plays a critical role in early anti-viral immune responses, in the regulation of autoimmune mechanisms and in cancer immunosurveillance. Our data demonstrate that in the elderly, naïve/memory B cell populations present a different expression of the studied receptors that could be discussed in terms of "inflamm-aging". In particular IgG(+)IgD(-)CD27(-) DN B cells show a tissue trafficking phenotype and they can be stimulated to produce GrB.

Centenarian offspring: a model for understanding longevity.

A main objective of current medical research is to improve the life quality of elderly people as priority of the continuous increase of ageing population. This phenomenon implies several medical, economic and social problems because of dramatic increase in number of non autonomous individuals affected by various pathologies. Accordingly, the research interest is focused on understanding the biological mechanisms involved in determining the positive ageing phenotype, i.e. the centenarian phenotype. In achieving this goal the choice of an appropriate study models is fundamental. Centenarians have been used as an optimal model for successful ageing. However, this model shows several limitations, i.e. the selection of appropriate controls and the use itself of the centenarians as a suitable model for healthy ageing. Thus, the interest has been centered on centenarian offspring, healthy elderly people. They may represent a model for understanding exceptional longevity for the following reasons: they exhibit a protective genetic background, cardiovascular and immunological profile, as well as a reduced rate of cognitive decline than age-matched people without centenarian relatives. Several of these aspects are summarized in this review based on the literature and the results of our studies.

Evidence for less marked potential signs of T-cell immunosenescence in centenarian offspring than in the general age-matched population.

People may reach the upper limits of the human life span at least partly because they have maintained more appropriate immune function, avoiding changes to immunity termed "immunosenescence." Exceptionally long-lived people may be enriched for genes that contribute to their longevity, some of which may bear on immune function. Centenarian offspring would be expected to inherit some of these, which might be reflected in their resistance to immunosenescence, and contribute to their potential longevity. We have tested this hypothesis by comparing centenarian offspring with age-matched controls. We report differences in the numbers and proportions of both CD4(+) and CD8(+) early- and late-differentiated T cells, as well as potentially senescent CD8(+) T cells, suggesting that the adaptive T-cell arm of the immune system is more "youthful" in centenarian offspring than controls. This might reflect a superior ability to mount effective responses against newly encountered antigens and thus contribute to better protection against infection and to greater longevity.