γδT淋巴细胞的抗肿瘤作用

粘膜免疫和固有免疫在对肿瘤的防御中起着重要作用。γδ型T细胞大量的分布于粘膜相关淋巴组织,其作用介于固有免疫和适应性免疫之间并且是MHC非限制性的。因此其在抗肿瘤免疫中的作用也是不可忽视的。以下将对其两个主要的功能亚群VγVδ2 T细胞和Vδ1 T细胞向肿瘤组织内浸润、对肿瘤细胞的识别及杀伤机制进行简要综述。     

γδT细胞在人乳头瘤病毒感染及宫颈癌发生中的作用

宫颈癌是严重威胁女性健康的疾病之一,几乎所有的流行病学调查均显示人乳头瘤病毒（HPV）感染是宫颈癌及癌前病变发病的主要条件.γδT细胞属于固有免疫细胞,是女性生殖器官上皮内淋巴细胞的主要成分.γδT细胞具有抗感染、抗肿瘤、免疫监视和免疫调节等作用,是固有免疫及适应性免疫间的桥梁.但某些肿瘤研究中也发现,γδT细胞同时具有免疫抑制作用,促进肿瘤的生长.文献报道宫颈癌患者肿瘤组织中存在着明显的γδT细胞浸润,且γδT细胞对宫颈癌细胞系有杀伤作用,这充分预示着γδT细胞在宫颈癌的发生中具有潜在的调节作用.因而研究γδT细胞抗HPV感染及其在宫颈癌及癌前病变中的作用具有重要意义.     

γδT细胞在疾病中的作用

γδT细胞是皮肤表皮内淋巴细胞和粘膜组织上皮内淋巴细胞的主要成分之一,为非特异性免疫细胞。活化的γδT细胞具有较强的杀伤活性,具有抗感染、抗肿瘤作用;γδT细胞还可以维持免疫耐受,调节免疫应签,异常可导致自身免疫性疾病的发生。因此尽管γδT细胞在人类庞大复杂的免疫体系中数量较少,但却具有不可替代的重要功能。     

信筒子醌升高小鼠胰腺癌CTL、NK、NKT和γδT细胞比例

正肿瘤浸润的免疫细胞包括骨髓来源的抑制性细胞(MDSCs)、Treg和细胞毒性淋巴细胞。MDSCs和Treg通过发挥免疫抑制功能促进肿瘤发展,而细胞毒性淋巴细胞在肿瘤微环境中发挥抑瘤作用。其中CTL是抗肿瘤免疫的主要效应细胞;另外,γδT、NKT和NK在抗瘤免疫监视中发挥作     

人T细胞抗原受体基因的命名

<正>人T细胞抗原受体(TCR)是由二硫键连接的二条多肽链(αβ或γδ)经组成的异二聚体,属lg基因超家族,每条链具有与lg分子相似的V区、D区(仅对β和δ链)J区和C区.根据TCR的不同,可将T细胞分为αβ~+T细胞和γδ~+T细胞.人外周血中95%的T细胞为αβ~+TCR,其配体是MHC-抗原肽复合物;而γδ~+TCR一般仅表达于CD4~-CD8T细胞,这些γδ~+T细胞识别的抗原结构目前尚不清楚,但在机体抗感染免疫和抗肿瘤免疫中发挥着重要的作用.从胸腺内的发育过程来看,αβ~+T细胞和γδ~+T细胞可能来源于同一祖先,而且γδTCR的表达要早于αβTCR,分别相当于妊娠第九周和第十周.     

免疫联合治疗增强Vγ9Vδ2 T细胞的抗肿瘤活性北大核心CSCD

细胞免疫疗法作为一种新型诊治手段在肿瘤治疗领域越发受到重视。γδT细胞具有良好的抗肿瘤特性,可识别恶性细胞、浸润肿瘤,在肿瘤细胞治疗和联合治疗中具有广阔应用前景。Vγ9Vδ2 T细胞是血液中最丰富的γδT细胞亚群,对卵巢癌、乳腺癌、白血病、肝癌等多种肿瘤细胞表现出良好杀伤能力。Vγ9Vδ2 T细胞虽然仅占外周血淋巴细胞少部分,但可由外周血单个核细胞大量扩增。免疫联合治疗的发展可提高基于Vγ9Vδ2 T细胞的联合治疗肿瘤杀伤效果。化疗药物、细胞因子、单克隆抗体等是诱导、扩增和干预Vγ9Vδ2 T细胞的有效药物。本文对Vγ9Vδ2 T细胞活化、肿瘤免疫杀伤作用和免疫联合治疗等进行综述。     

γδT细胞与病毒免疫

γδT细胞是指在T细胞受体上表达γ和δ链的一类T细胞亚群，已发现其具有抗肿瘤、抗感染、免疫调节等多种生物学活性。在对病毒感染的免疫中发挥重要的免疫监视作用。本文主要从病毒感染后机体内γδT细胞变化，γδT细胞抗病毒的机制，基于γδT细胞免疫的研究和临床应用等几个方面进行综述。     

γδT细胞

一小部分T细胞的受体不是由α和β多肽链构成的“常规”T细胞受体(TCRαβ),而是分别由γ和δ链取而代之(TCRγδ)。TCRγδ能够识别抗原。出现在T细胞个体发生的早期。在机体的某些部位,如小鼠的皮肤和肠道TCRγδ占优势,提示γδT细胞可能在抗感染的第一线起着防御作用γδT细胞能分泌淋巴因子,并具有细胞毒活性。由于MHC的非限制性以及CD_4、CD_8两阴性γδT细胞的发现,表明其激活过程可能与已知的αβT细胞不同。结核杆菌抗原能够优先激活γδT细胞,提示γδT细胞可能有一种特异的功能。γδT细胞的数量在许多疾病中稍有增加,但到目前的研究还未能证实γδT细胞有病原性作用。     

γδT细胞经唑来膦酸刺激后对骨肉瘤细胞的杀伤作用

目的:探讨外周血γδT细胞经唑来膦酸刺激后对骨肉瘤细胞株HOS的体内外杀伤作用及相关机制。方法:取健康人外周血5 mL,经唑来膦酸刺激后,在含IL-2的培养液中,培养14 d。用流式细胞仪测定γδT细胞所占的比例,用乳酸脱氢酶(LDH)释放法检测其对骨肉瘤细胞株HOS的体外杀伤作用,并用抗人γδTCR抗体、抗人NKG2D抗体和穿孔素/颗粒酶阻滞剂CMA分别预处理γδT细胞,观察杀伤作用的变化。另用骨肉瘤细胞株HOS注入BALB/c裸鼠皮下建立骨肉瘤裸鼠种植瘤模型。随机将裸鼠分为2组,分别为未治疗组、γδT细胞治疗组。观察裸鼠瘤体大小及称量瘤重。结果:PBMCs经唑来膦酸刺激14 d后γδT细胞阳性率达到(95±3)%。当效靶细胞比为6∶1、12∶1、25∶1、50∶1时,对HOS细胞的杀伤率分别为26.8%、31.5%、37.8%、40.9%。用Anti-γδTCR抗体、Anti-NKG2D抗体及CMA预处理γδT细胞后,当效靶细胞比为25∶1时,对HOS的杀伤率分别为32.3%、4.7%、16.7%。体内抑瘤实验中,γδT细胞治疗组的肿瘤生长抑制率为42.78%。结论:PBMCs经唑来膦酸刺激后,可获得高纯度的γδT细胞,在体内外其对骨肉瘤细胞株HOS有较强的杀伤作用。     

γδT细胞在感染性疾病中的研究进展

T细胞免疫应答在感染性疾病中发挥着抗感染和清除外来病原微生物的重要作用.根据TCR两条肽链构成的不同,可将T细胞分为αβT细胞和γδT细胞,αβT细胞在获得性免疫应答中发挥重要作用;而γδT细胞由于其分布特点和应答的非MHC限制性,在固有性免疫中发挥着独特的作用.随着研究的深入,其在获得性免疫应答中的作用也逐渐被揭示.γδT细胞是具有原始受体的第一线防御细胞和进程效应细胞,它在微生物感染免疫中的作用日益受到重视.我们就γδT细胞在细菌,病毒和寄生虫等病原体感染性疾病的研究进展做一综述.     

Human gammadelta T lymphocytes strip and kill tumor cells simultaneously

When human gammadelta lymphocytes bind to tumor cells for killing, they also strip their membrane for unknown reasons. Here we investigated this topic using the model of human gammadelta lymphocytes co-incubated with anaplastic large cell lymphomas, a group of tumors with cytolytic T or null lineage. By using flow cytometry and live cell imaging, we show that as soon as both cells were in contact, the TCR-mediated activation of gammadelta lymphocytes simultaneously triggered their secretion of lytic granules and stripping of lymphoma cell membranes, and both activities continued even after their cell death. However reciprocally in such conjugates, resistant lymphoma failed to strip gammadelta cells and to kill them by untargeted secretion of their own lytic granules. This indicated that secretion of lytic granules and target membrane stripping are associated in lytic cell conjugates, and that gammadelta T lymphocytes strip and kill their targets simultaneously.     

Early activation of gammadelta T lymphocytes in the elderly

T cell function is altered in vivo and in vitro in elderly compared with young subjects, and this alteration is believed to contribute to morbidity and mortality in man due to the greater incidence of infection, as well as autoimmunity and cancer in elderly. The majority of T cells express TCRalphabeta whereas TCRgammadelta is expressed on a minority of T cells. Moreover, it is known that gammadelta T lymphocytes display major histocompatibility complex (MHC)- unrestricted cytotoxicity that is reminiscent of natural killer (NK) activity. In view of earlier findings on both T cells and NK cells in the elderly, we hypothesised a different behaviour of gammadelta T lymphocytes from old subjects when compared with gammadelta T lymphocytes obtained from young people. Therefore, to gain further insight into mechanisms of immunosenescence in this little-studied population, we studied immunofluorescence analysis gammadelta T cells from the elderly. Our preliminary results show that the percentage of blood gammadelta T cells in lymphocytes from old subjects is decreased when compared with the young. Interestingly, these cells are more activated in the elderly than in young subjects; expression of CD69, an early activation marker, is increased in gammadelta T lymphocytes from old subjects after three hours of in vitro culture both with and without lipopolysaccharide stimulation. Thus, our findings, which need confirmation, strongly suggest that, in humans, gammadelta T cells are early responders when compared with alphabeta T cells. They may act as 'first aid' cells to replace the described deficit of the specific and aspecific immunity in elderly. In this view, the proinflammatory status, observable in the elderly, renders them ready to be stimulated by exogenous agents.     

Copulsing tumor antigen-pulsed dendritic cells with zoledronate efficiently enhance the expansion of tumor antigen-specific CD8+ T cells via Vgamma9gammadelta T cell activation

We demonstrate that Vgamma9gammadelta T cells activated by zoledronate can link innate and acquired immunity through crosstalk with dendritic cells (DCs) in a way that can amplify activation and proliferation of tumor antigen-specific CD8+ T cells. DCs pulsed with antigen alone or antigen plus zoledronate were used to stimulate the in vitro expansion of antigen-specific CD8+ T cells. MART-1-modified peptide (A27L peptide) and apoptotic HLA-A*0201-positive, MART-1-positive JCOCB tumor cell lines were used as tumor antigen sources. The percentage of A27L-specific CD8+ T cells within the responding lymphocytes on Day 7 when immature DCs (imDCs) were cultured in the presence of A27L peptide and 0.01 microM zoledronate was significantly higher (P=0.002, n=11) than that observed when imDCs were cultured with the lymphocytes in the presence of the A27L peptide alone. This enhancing effect of zoledronate was significantly reduced when gammadelta T cells were depleted from responding lymphocytes (P=0.030, n=5), indicating that the effect is mediated mainly through Vgamma9gammadelta T cells activated by zoledronate-pulsed imDCs. When imDCs copulsed with zoledronate and apoptotic JCOCB tumor cell lines were used, the percentage of A27L-specific CD8+ T cells was higher than that observed using imDCs with the apoptotic JCOCB lines alone, suggesting that zoledronate treatment of imDCs enhances the cross-presentation ability of DCs. These findings suggest a potentially valuable role for Vgamma9gammadelta T cell activation for expanding antigen-specific CD8+T cells using DCs copulsed with tumor antigen and zoledronate in the design of vaccine therapies for malignancy.     

Tumor recognition following Vgamma9Vdelta2 T cell receptor interactions with a surface F1-ATPase-related structure and apolipoprotein A-I

Vgamma9Vdelta2 T lymphocytes, a major gammadelta T lymphocyte subset in humans, display cytolytic activity against various tumor cells upon recognition of yet uncharacterized structures. Here, we show that an entity related to the mitochondrial F1-ATPase is expressed on tumor cell surface and promotes tumor recognition by Vgamma9Vdelta2 T cells. When immobilized, purified F1-ATPase induces selective activation of this lymphocyte subset. The Vgamma9Vdelta2 T cell receptors (TCR) and the F1-ATPase also bind a delipidated form of apolipoprotein A-I (apo A-I), as demonstrated by surface plasmon resonance. Moreover, the presence of apo A-I in the culture medium is required for optimal activation of Vgamma9Vdelta2 T cells by tumors expressing F1-ATPase. This study thus describes an unanticipated tumor recognition mechanism by Vgamma9Vdelta2 lymphocytes and a possible link between gammadelta T cell immunity and lipid metabolism.     

Age-related propensity to peripheral expansion of Vgamma3+ gammadelta+ T lymphocytes after irradiation and bone marrow transplantation

The age-related decline in T cell functions is generally considered to be due to changes in the responding alphabeta T cell populations as a result of impairment of T cell differentiation in the thymus. T cells bearing the gammadelta TCR are normally a minor subset of circulating T cells, but often the major T cell type among lymphocytes in epithelial tissues. In this paper we show that gammadelta T cells are expanded in lymph nodes of irradiated mice after syngenic bone marrow transplantation. Interestingly, these gammadelta T cells express mainly the Vgamma3 TCR, which is characteristic of dendritic epithelial T cells that can develop in athymic nude mice and may recognize self antigens. Since the peripheral expansion of Vgamma3 T lymphocytes is closely related to bone marrow age, these observations indicate that the age-related propensity to extrathymic development of Vgamma3+ gammadelta+ T lymphocytes is mainly due to stem cell dysregulation in aging. This phenomenon may contribute to T cell impairment and to the increased natural cytotoxic activity of lymphoid cells in aged mice.      

Antigen recognition by human gammadelta T lymphocytes

Mature T lymphocytes carrying the conventional alphabeta T cell receptor (TCR) recognize peptide antigens in the context of MHC class I (CD8+) and MHC class II (CD4+) antigens, respectively. In striking contrast, human gammadelta T lymphocytes recognize unconventional antigens via their heterodimeric TCR in a non-MHC-restricted fashion. In this brief review, we discuss recent progress in the identification of ligands that are specifically recognized by human gammadelta T cells. It appears that gammadelta T cells have evolved to supplement the cellular immune response towards antigens that are not seen by alphabeta T lymphocytes.     

Co-stimulatory signals increase the reactivity of gammadelta T cells towards mycobacterial antigens

Although it has been shown that gammadelta T lymphocytes are able to react with different cell-associated or soluble antigens, the immune repertoire of these cells appears to be skewed to the recognition of mycobacterial antigens. We have studied the number and reactivity of gammadelta T cells towards several mycobacterial antigens in patients with tuberculosis and leprosy, as well as their healthy contacts and control individuals. We found an increased number of Vdelta2+ cells in healthy contacts (PPD+ and lepromin+) and tuberculoid leprosy patients. The gammadelta T cells from lepromatous leprosy showed a decreased response to all antigens tested, but some of these patients exhibited a significant response to the 30-kD glycoprotein of Mycobacterium tuberculosis. Interestingly, the reactivity of gammadelta T cells against mycobacterial antigens was significantly increased by costimulatory signals generated through CD7, LFA-1, CD50 and CD69 in all groups. However, signalling through CD69 did not enhance the responsiveness of gammadelta lymphocytes from lepromatous patients. On the other hand, the in vitro blockade of IL-10 with a specific antibody enhanced the cell proliferation of gammadelta lymphocytes from lepromatous leprosy patients, whereas exogenous IL-10 had an opposite effect in most individuals studied. These results suggest the potential role of different cell membrane receptors in the regulation of gammadelta T cell proliferation induced by mycobacteria, as well as the possible involvement of IL-10 in this phenomenon.     

The CD4+ T cell immunodominant Anaplasma marginale major surface protein 2 stimulates gammadelta T cell clones that express unique T cell receptors

Major surface protein 2 (MSP2) of the bovine rickettsial pathogen Anaplasma marginale is an abundant, serologically immunodominant outer membrane protein. Immunodominance partially results from numerous CD4+ T cell epitopes in highly conserved amino and carboxy regions and the central hypervariable region of MSP2. However, in long-term cultures of lymphocytes stimulated with A. marginale, workshop cluster 1 (WC1)+ gammadelta T cells and CD4+ alphabeta T cells proliferated, leading to a predominance of gammadelta T cells. As gammadelta T cells proliferate in A. marginale-stimulated lymphocyte cultures, this study hypothesized that gammadelta T cells respond to the abundant, immunodominant MSP2. To test this hypothesis, gammadelta T cell clones were isolated from MSP2 vaccinates and assessed for antigen-specific proliferation and interferon-gamma secretion. Seven WC1+ gammadelta T cell clones responded to A. marginale and MSP2, and three of these proliferated to overlapping peptides from the conserved carboxy region. The gammadelta T cell response was not major histocompatibility complex-restricted, although it required antigen-presenting cells and was blocked by addition of antibody specific for the T cell receptor (TCR). Sequence analysis of TCR-gamma and -delta chains of peripheral blood lymphocytes identified two novel TCR-gamma chain constant (Cgamma) regions. It is important that all seven MSP2-specific gammadelta T cell clones used the same one of these novel Cgamma regions. The TCR complementarity-determining region 3 was less conserved than those of MSP2-specific CD4+ alphabeta T cell clones. Together, these data indicate that WC1+ gammadelta T cells recognize A. marginale MSP2 through the TCR and contribute to the immunodominant response to this protein.     

Comparative gene expression by WC1+ gammadelta and CD4+ alphabeta T lymphocytes, which respond to Anaplasma marginale, demonstrates higher expression of chemokines and other myeloid cell-associated genes by WC1+ gammadelta T cells

The functions of gammadelta T cells are enigmatic, and these cells are often considered as evolutionary remnants of well-characterized alphabeta T cells. However, their conservation throughout evolution suggests that gammadelta T cells are biologically unique. In ruminants, gammadelta T cells expressing the workshop cluster 1 (WC1) scavenger receptor comprise a large proportion of circulating lymphocytes, suggesting these cells are biologically relevant and functionally different from alphabeta T cells. In fact, bovine WC1(+) gammadelta T cells can act as APC for alphabeta T cells, indicating they may express genes encoding proteins associated with innate immunity. The present study was designed to compare immune function gene expression profiles of clonal populations of WC1(+) gammadelta and CD4(+) alphabeta T cells derived from the same animal, which respond to major surface protein 2 (MSP2) of the intraerythrocytic rickettsial pathogen of cattle, Anaplasma marginale. Gene expression profiles of activated T cell clones were compared using a microarray format, and differential gene expression was confirmed by real-time RT-PCR and protein analyses. We demonstrate that although MSP2-specific alphabeta and gammadelta T cell clones express many of the same genes, gammadelta T cell clones express high levels of genes associated with myeloid cells, including chemokines CCL2, CXCL1, CXCL2, CXCL6, and surface receptors CD68, CD11b, macrophage scavenger receptor 1, macrophage mannose receptor, and galectin-3. It is important that many of these genes were also expressed at higher levels in polyclonal WC1(+) gammadelta T cells when compared with CD4(+) alphabeta T cells selected from peripheral blood.