Pien Tze Huang alleviates Concanavalin A-induced autoimmune hepatitis by regulating intestinal microbiota and memory regulatory T cells

BACKGROUND Traditional Chinese medicine has used the drug Pien Tze Huang(PTH),a classic prescription,to treat autoimmune hepatitis(AIH).However,the precise mode of action is still unknown.AIM To investigate the mechanism of PTH in an AIH mouse model by determining the changes in gut microbiota structure and memory regulatory T(mTreg)cells functional levels.METHODS Following induction of the AIH mouse model induced by Concanavalin A(Con A),prophylactic administration of PTH was given for 10 d.The levels of mTreg cells were measured by flow cytometry,and intestinal microbiota was analyzed by 16S rRNA analysis,while western blotting was used to identify activation of the toll-like receptor(TLR)2,TLR4/nuclear factor-κB(NF-κB),and CXCL16/CXCR6 signaling pathways.RESULTS In the liver of mice with AIH,PTH relieved the pathological damage and reduced the numbers of T helper type 17 cells and interferon-γ,tumor necrosis factor-alpha,interleukin(IL)-1β,IL-2,IL-6,and IL-21 expression.Simultaneously,PTH stimulated the abundance of helpful bacteria,promoted activation of the TLR2 signal,which may enhance Treg/mTreg cells quantity to produce IL-10,and suppressed activation of the TLR4/NF-κB and CXCL16/CXCR6 signaling pathways.CONCLUSION PTH regulates intestinal microbiota balance and restores mTreg cells to alleviate experimental AIH,which is closely related to the TLR/CXCL16/CXCR6/NF-κB signaling pathway.

Stem cell-like memory T cells:Role in viral infections and autoimmunity

Stem cell-like memory T(TSCM)cells possess stem cell properties including multipotency and self-renewal and are being recognized as emerging players in various human diseases.Advanced technologies such as multiparametric flowcytometry and single cell sequencing have enabled their identification and molecular characterization.In case of chronic viral diseases such as human immunodeficiency virus-1,CD4+T_(SCM) cells,serve as major reservoirs of the latent virus.However,during immune activation and functional exhaustion of effector T cells,these cells also possess the potential to replenish the pool of functional effector cells to curtail the infection.More recently,these cells are speculated to play important role in protective immunity following acute viral infections such as coronavirus disease 2019 and might be amenable for therapeutics by ex vivo expansion.Similarly,studies are also investigating their pathological role in driving autoimmune responses.However,there are several gaps in the understanding of the role of T_(SCM) cells in viral and autoimmune diseases to make them potential therapeutic targets.In this minireview,we have attempted an updated compilation of the dyadic role of these complex T_(SCM) cells during such human diseases along with their biology and transcriptional programs.

Memory AND effector cells in children with bacterial infections of the gastrointestinal and respiratory tracts

Infections in infants and children under five years of age are a public health in México and are one of the major causes of death. Methods In this study, lymphocyte immunophenotyping for CD3+ (T-cells), CD3+CD4+, CD3+CD8+, CD3+CD19+, CD3+CD16/56+, CD45RA+, CD45RO+, CD62L- and CD28- were determined in the whole blood of gastrointestinal and respiratory bacterial infected children, using a four-color flow cytometry technique. Results: Our data showed that the percentages and the absolute numbers of monocytes and granulocytes are increased in infected children, when compared to the control group. Similarly, we observed increases in the percentages of B lymphocytes, CD8+ cells, memory T cells (CD4+CD45RO+ and CD8+CD45RO+) and effector lymphocytes (CD4+CD62L? and CD8+CD28?) in infected children compared with the control group. In contrast, naive T cells were decreased in the bacterial infected children relative to the control group. Additionally, we used ELISA assays to identify the pathogen agent in gastrointestinal and respiratory infection. Comparing different types of infection, we found that the children with respiratory bacterial infections had higher percentages of B lymphocytes, and cytotoxic lymphocytes (CD8+CD28-);and the children with gastrointestinal infections had higher percentages of CD3+ lymphocytes and effector cells (CD4+CD62L-). Conclusions The increase in B lymphocytes and CD8+CD28- cells in the children with respiratory infections and the increase of T lymphocytes and CD4+CD62L- cells in the children with gastrointestinal bacterial infections indicate that both cellular and humoral responses coincide, and both responses are necessary for eliminating the pathogen.

Memory stem T cells generated by Wnt signaling from blood of human renal clear cell carcinoma patients

Objective: Memory stem T cells(Tscm) have attracted attention because of their enhanced self-renewal, multipotent capacity, and anti-tumor capacities. However, little is known about Tscm in patients with renal clear cell carcinoma(RCC) and the role of Wnt signaling in these cells. We evaluated Tscm from RCC patients concerning their activation of Wnt signaling in vitro and explored the mechanism of preferential survival.Methods: Flow cytometry identified surface markers and cytokines produced from accumulated Tscm in the presence of the glycogen synthase kinase beta inhibitor TWS119. Apoptosis was evaluated after induction using tumor necrosis factor-alpha.Immunofluorescence and Western blot analyses were used to investigate the activation of the nuclear factor-kappa B(NF-КB)pathway.Results: RCC patients had a similar percentage of CD4^+ and CD8^+ Tscm as healthy donors. Activation of Wnt signaling by TWS119 resulted in the accumulation of Tscm in activated T cells, but reversal of differentiated T cells to Tscm was not achieved.Preferential survival of Tscm was associated with increased anti-apoptotic ability mediated downstream of the NF-КB activation pathway.Conclusions: The finding that Tscm can accumulate by Wnt signaling in vitro in blood from RCC patients will help in devising new cancer therapy strategies of Tscm-based adoptive immunotherapy, such as dendritic cell-stimulated Tscm, and T cell receptor or chimeric antigen receptor-engineered Tscm.

Low-dose intralesional injection of 5-fluorouracil and triamcinolone reduces tissue resident memory T cells in chronic eczema

BACKGROUND Tissue resident memory T(TRM)cells have been reported to play a significant role in the pathogenesis and relapse of chronic eczema.AIM To compare the efficacy and safety of the intralesional injection of 5-fluorouracil(5-FU)and triamcinolone(TA)with those associated with TA alone for the treatment of chronic eczema.METHODS A total of 168 patients were randomized to 5-FU+TA or TA groups and received a one-time intralesional injection of 5-FU+TA or TA only.Biopsies were collected before and 2 wk after treatment for evaluation of histopathological changes.All patients were followed up monthly for up to 1 year.RESULTS No serious adverse event was observed in either group.Although the mean atopic dermatitis severity index scores and effective rates were comparable between the two groups after 2 wk of treatment,the relapse rate was significantly lower in the 5-FU+TA group than in the TA group.Histological examination showed significantly fewer CD8^(+)and CD103^(+)T cells but not CD4^(+)T cells in the 5-FU+TA group.CONCLUSION One-time intralesional injection of 5-FU+TA is effective and safe for chronic eczema treatment and can further reduce the retention of T_(RM) cells in the lesional skin and the relapse rate of chronic eczema.

Cytotoxic CD8+ T cells and tissue resident memory cells in colorectal cancer based on microsatellite instability and BRAF status

BACKGROUND Recent studies in non-colorectal malignancy have associated T resident memory(T_(RM)) cells with improved patient survival. It is unknown if T_(RM) plays a role in colorectal cancer(CRC).AIM To examine the potential role of T_(RM) cells in providing immunogenicity in CRC stratified by microsatellite instability(MSI) and BRAF status.METHODS Patients with known MSI and BRAF mutation status were eligible for inclusion in this study. CRC tumour sections stained with haematoxylin and eosin were microscopically reviewed and the images scanned prior to assessment for location of invading edge and core of tumour. Sequential sections were prepared for quantitative multiplex immunohistochemistry(IHC) staining. Opal Multiplex IHC staining was performed with appropriate positive and negative controls and imaged using a standard fluorescent microscope fitted with a spectral scanning camera(Mantra) in conjunction with Mantra snap software. Images were unmixed and annotated in in Form 2.2.0. Statistical analysis was performed using Graphpad Prism Version 7 and Stata Version 15.RESULTS Seventy-two patients with known MSI and BRAF status were included in the study. All patients were assessed for MSI by IHC and high resolution capillary electrophoresis testing and 44 of these patients successfully underwent quantitative multiplex IHC staining. Overall, there was a statistically significant increase in CD8+ T_(RM) cells in the MSI(BRAF mutant and wild type) group over the microsatellite stable(MSS) group. There was a statistically significant difference in CD8+ T_(RM) between high level MSI(MSI-H):BRAF mutant [22.57, 95% confidence interval(CI): 14.31-30.84] vs MSS [8.031(95%CI: 4.698-11.36)], P = 0.0076 and MSI-H:BRAF wild type [16.18(95%CI: 10.44-21.93)] vs MSS [8.031(95%CI: 4.698-11.36)], P = 0.0279. There was no statistically significant difference in CD8 T cells(both CD8+CD103-and CD8+CD103+T_(RM)) between MSI-H: BRAF mutant and wild type CRC.CONCLUSION This study has shown that CD8+ T_(RM) are found in greater abundance in MSI-H CRC, both BRAF mutant and MSI-H:BRAF wild type, when compared with their MSS counterpart. CD8+ T_(RM) may play a role in the immunogenicity in MSI-H CRC(BRAF mutant and BRAF wild type). Further studies should focus on the potential immunogenic qualities of T_(RM) cells and investigate potential immunotherapeutic approaches to improve treatment and survival associated with CRC.

Regulation of neuroinflammatory properties of glial cells by T cell effector molecules

Multiple sclerosis （MS） is a chronic inflammatory and neurodegenerative disorder that is thought to be mediated by autoreactive T lymphocytes that find their way into the central nervous system （CNS）. The pathological mechanism of MS is still being elucidated but it involves complex interactions between infiltrating immune cells and resi- dent glial cells within the CNS that culminate into strong neuroinflammation and axonal damage.

Are CD45RO^(+)and CD45RA^(-)genuine markers for bovine memory T cells?

Effective vaccination in duces memory T cells,which protect the host against pathogen re-infecti ons.Therefore,detection of memory T cells is essential for evaluating vaccine efficacy,which was originally dependent on cytokine induction assays.Currently,two isoforms of CD45 tyrosine phosphatase,CD45RO expression and CD45RA exclusion(CD45RO^(+)/CD45RA^(-)) are used extensively for detecting memory T cells in cattle.The CD45RO^(+)/CD45RA^(-) markers were first established in humans around three decades ago,and were adopted in cattle soon after.However,in the last two decades,some published data in humans have challenged the initial paradigm,and required multiple markers for identifying memoryT cells.On the contrary,memoryT cell detection in cattle still mostly relies on CD45RO^(+)/CD45RA^(-)despite some con troversial evidence.In this review,we summarized the current literature to exami ne if CD45RO^(+)/CD45RA^(-)are valid markers for detecting memoryT cells in cattle.It seems CD45RA and CD45RO(CD45RA/RO)as markers for identifyi ng bovine memoryT cells are questi on able.

Function of Helper T Cells in the Memory CTL-mediated Anti-tumor Immunity

To investigate the role of CD4 + helper T (Th) cells in the memory CTL-mediated anti-tumor immunity, the RAG-1 gene knock out mice were adoptively transferred with OT-1 cells to generate the memory CTL, the C57BL/6 mice immunized with the epitope peptide of OVA specific Th cells and with different adjuvants were adoptively transferred with these memory-CTLs, and then the animals were challenged with tumor cells EG7. It was found that although the simple immunization of mice with the epitope peptide of the OVA specific Th cells could generate more effect CTL, but this effect was not so strong enough to resist completely the challenges with tumor cells. Nevertheless, the memory CTL-mediated anti-tumor immune effect required the helps of Th1 and Th2 cells. The cross-regulation between Th1 and Th2 cells seemed to be beneficial for the host to generate more effector CTL for mounting an efficient anti-tumor response. It concluded that the interaction between Th1 and Th2 cells might be more important than the single subset of Th cells in the memory CTL-mediated anti-tumor immune response. More attention should be paid in this regard for the future studies.

Role of OX40 in mechanisms of memory T cells in islet transplant tolerance

Objective To investigate the role of OX40 in the mechanisms of memory T cells in islet transplant tolerance. Methods The expression of OX40 on native, like memory and memory CD8 + T cells was detected by RT - PCR. Splenic T ceels from B6 mice were injected into Rag - / - mice via the tail vein,and the Rag mice were divided into three groups ( n = 8 each) :

雌性和雄性非肥胖糖尿病小鼠中CD8^(+)T细胞分化亚群差异研究

目的以雌性和雄性非肥胖糖尿病(nonobese diabetic,NOD)小鼠以及健康对照癌症研究所(institute for cancer research,ICR)小鼠为研究对象,比较分析初始、效应、记忆、耗竭以及调节性CD8^(+)T细胞分化亚群差异,探讨1型糖尿病(type 1 diabetes,T1D)背景下的性别因素对CD8^(+)T细胞分化命运的影响。方法采用流式细胞术检测雌雄NOD小鼠脾脏、胰腺引流淋巴结(pancreatic draining lymph nodes,pLN)、胰腺浸润淋巴细胞(pancreas-infiltrating lymphocytes,PIL)、初始T细胞(naive T cells,T_(N))、中枢记忆T细胞(central memory T cells,T_(CM))、效应T细胞(effector T cells,T_(EFF))、效应前体样T细胞(effector precursor T cells,T_(EP))、耗竭T细胞(exhausted T cells,T_(EX))、耗竭前体T细胞(precursor exhausted T cells,T_(PEX))以及调节性T细胞(regulatory T cells,Tregs)等CD8^(+)T细胞分化亚群的频率和表型差异。结果与雄性NOD小鼠比较,雌性NOD小鼠pLN及PIL中IFN-γ^(+)、CD107a^(+)和CCL5^(+)CD8^(+)T_(EFF)频率显著升高(P<0.01,P<0.05,P<0.05),同时脾脏中CD8^(+)T_(N)、CD8^(+)T_(CM)、CD8^(+)T_(EX)、CD8^(+)T_(PEX)和CD122^(+)CD8^(+)Tregs亚群的频率均显著降低(P<0.01,P<0.01,P<0.01,P<0.01,P<0.001);而雌性和雄性ICR小鼠体内除CD122^(+)CD8^(+)Tregs差异变化与NOD小鼠一致(P<0.05),其余上述各CD8^(+)T细胞分化亚群无显著差异。结论雄激素可能通过抑制记忆T细胞向效应T细胞分化,同时促进效应T细胞功能耗竭,导致雌雄发病率差异。

Neutrophils inhibit CD8^(+)T cells immune response by arginase-1 signaling in patients with sepsis

BACKGROUND:Patients with sepsis often exhibit an acute inflammatory response,followed by an immunosuppressive phase with a poor immune response.However,the underlying mechanisms have not been fully elucidated.METHODS:We sought to comprehensively characterize the transcriptional changes in neutrophils of patients with sepsis by transcriptome sequencing.Additionally,we conducted a series of experiments,including real-time quantitative polymerase chain reaction(RT-qPCR)and flow cytometry to investigate the role of arginase-1 signaling in sepsis.RESULTS:Through the analysis of gene expression profiles,we identified that the negative regulation of T cell activation signaling was enriched,and the expression of arginase-1 was high in neutrophils from patients with sepsis.Furthermore,we conducted flow cytometry and found that the function of CD8^(+)T cells in septic patients was impaired.Moreover,neutrophils from septic patients inhibited the percentage of polyfunctional effector CD8^(+)T cells through arginase-1.Additionally,the proportions of granzyme B^(+)IFN^(-)γ^(+)CD8^(+)T and TNF^(-)α^(+)IFN^(-)γ^(+)CD8^(+)T cells increased after inhibition of arginase-1 signaling.CONCLUSION:The impaired effector function of CD8^(+)T cells could be restored by blocking arginase-1 signaling in patients with sepsis.

Memory CD8+ T cell differentiation in viral infection: A cell for all seasons

Chronic viral infections such as hepatitis B virus (HBV), hepatitis C virus (HCV) and human immunodeficiency virus (HIV) are major global health problems affecting more than 500 million people worldwide. Virus-specific CD8+ T cells play an important role in the course and outcome of these viral infections and it is hypothesized that altered or impaired differentiation of virus- specific CD8+ T cells contributes to the development of persistence and/or disease progression. A deeper understanding of the mechanisms responsible for functional differentiation of CD8+ T cells is essential for the generation of successful therapies aiming to strengthen the adaptive component of the immune system.

记忆型双特异性CAR-T细胞的工艺优化研究

目的 研究能够显著降低CAR-T细胞的体外分化程度、维持记忆型CAR-T(CAR-Tm)细胞高浓度稳态的新工艺路径,提升和延长CAR-T细胞的肿瘤杀伤效果。方法 采用流式细胞分析(FACS)技术,对原工艺采用CD3/CD28磁珠分选CD3^(+)T细胞,在体外培养过程中不断补充IL-2细胞因子,和新工艺利用CD4/CD8磁珠分选出CD4^(+)和CD8^(+)T细胞并用耦联人源化抗体纳米粒(TransAct)活化,在体外培养过程中添加IL-7和IL-15培养所得T细胞分别进行CAR-Tm细胞亚群分析,并通过对比不同TransAct用量和培养时间获得最优制备工艺。结果 新工艺得到的低分化记忆型CAR-T(CAR-Tscm^(+)CAR-Tcm亚群)细胞占总T细胞和CAR-T细胞的比例显著高于原工艺(P<0.05),TransAct的最佳用量为20%,细胞体外最佳培养时间为12 d。结论 联用IL-7细胞因子、IL-15细胞因子、TransAct有利于维持靶向CD19/CD37双特异性低分化CAR-Tm细胞高位数量和维持时间,提高持久性,为其后续临床研究及产业化奠定了基础。

基于组织驻留记忆CD4^(+)T细胞探讨溃疡性结肠炎复发过程中“伏邪”的生物学基础

从组织驻留记忆CD4^(+)T细胞(CD4^(+)TRM)细胞入手,综述其生理病理特点及其在溃疡性结肠炎(UC)复发中的作用,探讨UC复发过程中“伏邪”的生物学基础,为中医药抗UC复发提供新策略。CD4^(+)TRM细胞在UC的发病机制中具有核心作用,参与了UC肠道炎症的反复发作。伏邪是感邪后藏伏于体内不立即发病的邪气,或湿热瘀血等邪气并未随疾病治愈根除而是潜伏于内的病邪,是UC反复发作、迁延难愈的主要病因。伏邪的致病特点与CD4^(+)TRM细胞免疫记忆、感而引动、待机而发的特性暗相契合,因此CD4^(+)TRM细胞可能是UC“伏邪”的生物学基础之一。

Impact of T cells on hematopoietic stem and progenitor cell function:Good guys or bad guys?

When hematopoietic stem and progenitor cells(HSPC)are harvested for transplantation, either from the bone marrow or from mobilized blood, the graft contains a significant number of T cells. It is these T cells that are the major drivers of graft-vs-host disease(Gv HD). The risk for Gv HD can simply be reduced by the removal of these T cells from the graft. However, this is not always desirable, as this procedure also decreases the engraftment of the transplanted HSPCs and, if applicable, a graft-vs-tumor effect. This poses an important conundrum in the field: T cells act as a double-edged sword upon allogeneic HSPC transplantation, as they support engraftment of HSPCs and provide anti-tumor activity, but can also cause Gv HD. It has recently been suggested that T cells also enhance the engraftment of autologous HSPCs, thus supporting the notion that T cells and HSPCs have an important functional interaction that is highly beneficial, in particular during transplantation. The underlying reason on why and how T cells contribute to HSPC engraftment is still poorly understood. Therefore, we evaluate in this review the studies that have examined the role of T cells during HSPC transplantation and the possible mechanisms involved in their supporting function. Understanding the underlying cellular and molecular mechanisms can provide new insight into improving HSPC engraftment and thus lower the number of HSPCs required during transplantation. Moreover, it could provide new avenues to limit the development of severe Gv HD, thus making HSPC transplantations more efficient and ultimately safer.

吉兰-巴雷综合征患者外周血记忆性T细胞和记忆性B细胞亚群的变化及其临床意义

目的探讨吉兰-巴雷综合征(Guillain-Barrésyndrome,GBS)患者外周血记忆性T细胞和记忆性B细胞亚群的变化及其临床意义。方法选取2018年6月至2020年12月于徐州医科大学附属医院神经内科住院的16例GBS患者作为研究组,并选取同期16名来院的健康体检者作为对照组。流式细胞术检测两组入选者的外周血T细胞亚群,包括CD4^(+)初始T细胞(naive T cells,TN)、CD4^(+)中央记忆性T细胞(central memory T cells,TCM)、CD4^(+)效应记忆性T细胞(effector memory T cells,TEM)和CD4^(+)终末分化效应记忆性T细胞(terminally differentiated effector memory T cells,TEMRA)及记忆性B细胞、浆母细胞的占比并分析其临床价值。结果与对照组相比,研究组患者的CD4^(+)TN及CD8^(+)TN均明显下降(P<0.05),CD4^(+)TEM及CD8^(+)TEM均明显升高(P<0.05),TCM及TEMRA在CD4和CD8上的比例比较,差异无统计学意义(P>0.05)。与对照组相比,研究组记忆性B细胞比例明显升高(P<0.05),两组患者间浆母细胞占比比较,差异无统计学意义(P>0.05)。GBS患者外周血CD4^(+)TEM及CD8^(+)TEM占比与Hughes残疾评分、脑脊液蛋白、脑脊液免疫球蛋白G及记忆性B细胞占比均呈正相关(P<0.05)。结论GBS患者存在记忆性T细胞和记忆性B细胞亚群免疫紊乱,CD4^(+)TEM细胞、CD8^(+)TEM细胞及记忆性B细胞占比升高,这很可能是GBS发病过程中重要的外周免疫机制。

肿瘤相关性贫血与SARS-CoV-2特异性记忆CD8^(+)T细胞丰度的相关性分析

目的 探讨肿瘤相关性贫血对外周血中新型冠状病毒特异性记忆CD8^(+)T细胞丰度的影响。方法 纳入2023年6-7月在火箭军特色医学中心住院治疗的HLA-A*11∶01阳性中晚期实体瘤患者34例。根据血红蛋白浓度将患者分为无贫血组(HGB≥120 g/L,n=14)、轻度贫血组(120 g/L> HGB≥90 g/L,n=14)与中重度贫血组(HGB<90 g/L,n=6)。分离外周血单个核细胞,利用新冠病毒抗原表位刺激并扩增记忆CD8^(+)T细胞,使用ELISPOT筛选阳性表位,构建Tetramer。利用扩增后细胞检测Tetramer+细胞比例、数量及ELISPOT斑点数,用以反映新冠病毒特异性记忆CD8^(+)T细胞丰度。分析患者血红蛋白浓度与Tetramer+细胞比例、数量及ELISPOT斑点数的相关性。分析不同贫血组Tetramer+细胞比例、数量及ELISPOT斑点数的差异。结果 34例患者中男性25例,女性9例;年龄36~78岁,中位年龄57岁。患者扩增后Tetramer+细胞比例、数量及ELISPOT斑点数与血红蛋白浓度均呈正相关关系(P<0.05);与无贫血组相比,中重度贫血组患者Tetramer+细胞比例、数量及ELISPOT斑点数均明显降低(P<0.05)。结论 肿瘤患者外周血新冠病毒特异性记忆CD8^(+)T细胞的丰度与血红蛋白浓度正相关,提示肿瘤相关性贫血可能通过降低外周血中记忆CD8^(+)T细胞的丰度导致患者病毒易感性增高。

Memory Phenotypes of HIV-Specific CD8+ T Cell Responses Are Independent of Functional Activity as Defined by Cytokine Output

Objectives: The definition of CD8+ T cell attributes that mediate protective immunity in HIV dis-ease progression has not been clearly defined. Although our ability to characterize these cells continues to improve, the extent to which specific memory phenotypic categories of CD8+ T cells reliably represent their functional attributes remains controversial. Methods: We simultaneously assessed surface phenotype and functionality of HIV-specific CD8+ T cells by multiparametric flow cytometry, measuring five CD8+ T cell functions (CD107a, IFNγ, MIP-1β, TNFα and IL2) and phenotypic markers CCR7, CD45RA, and CD27, in parallel in 24 HIV-infected individuals. Results: Virus-specific responses were contained within all eight phenotypic categories defined using CCR7, CD45RA, and CD27. Phenotypic profiles of HIV-specific cells differed from CEF-specific cells, with HIV-specific cells having higher levels of CD45RA (p = 0.008). Interestingly a large portion of CEF and HIV-specific cells were found within previously undefined phenotypes CCR7+CD27-CD45RA+ (14.6% and 17.2%, respectively) and CCR7+CD27-CD45RA-(14.8% and 15.8%, respectively). In addition, up to 10% - 20% of responding cells were phenotypically “naive”. Additionally, memory phenotypes of cells exhibiting monofunctional and polyfunctional responses frequently differed, and failed to associate with a consistent phenotype representing functionally active cells. Conclusion: These data suggest that particularly after antigen stimulation, that surface phenotypes defined by CCR7, CD27 and CD45RA expression on antigen-specific CD8+ T cells, reflect a wide range of immunological functions, and that no single phenotype defined by memory marker expression can reliably be used to identify functional capacity.