一例慢性移植物抗宿主病患者TCR Vβ细胞分布和克隆性的研究

目的 了解非血缘关系骨髓移植后生移植特抗宿主病（ｃＧＶＨＤ）患者的Ｔ细胞受体（ＴＣＲ）ＶβＴ细胞的分布和克隆性。方法 应用逆转录－聚合酶链反应（ＲＴ－ＰＣＲ）扩增１例非血缘关系骨髓移植后ｃＧＶＨＤ患者的外周血单个核细胞的ＴＣＲ Ｖβ２４个亚家族的ＣＤＲ３。了解患者ＴＣＲ ＶβＴ细胞的分布情况,ＰＣＲ产物进一步经基因扫描分析确定Ｔ细胞克隆性。结果 患者存在８个ＴＣＲ Ｖβ亚家族Ｔ细胞;其中Ｖβ２、Ｖ     

非霍奇金淋巴瘤病人外周血T细胞TCR Vβ谱系的选择性利用和克隆性增殖分析

为了解B细胞性非霍奇金淋巴瘤（B－NHL）和T细胞性非霍奇金淋巴瘤（T－NHL）病人TCR Vβ亚家族T细胞的分布及其克隆性的情况，利用RT－PCR分别扩增4例B－NHL和2例T－NHL病人外周血单个核细胞的TCR Vβ24个亚家族基因的CDR3，了解病人各Vβ亚家族的利用情况。阳性的PCR产物进一步经荧光素标记和基因扫描分析产物的CDR3长度，以了解T细胞克隆性。结果显示，6例NHL病人外周血T细胞仅选择性表达6－12个Vβ亚家族，全部病人均选择了表达Vβ，Vβ8，Vβ13和Vβ19，5例病人表达Vβ2和Vβ16，而全部病人均未能检测到Vβ4－6，Vβ10－12，Vβ15，Vβ17－18，Vβ20，Vβ22－23。基因扫描发现2例B－NHL和1例T－NHL病人的1－3个Vβ亚家族T细胞呈克隆性增殖。结论提示，B－NHL和T－NHL病人外周血T细胞具有相似的Vβ亚家族选择性利用的特点，部分病人存在与肿瘤细胞抗原相关的克隆性增殖的T细胞。     

急性早幼粒细胞白血病患者中TCR Vβ T细胞体内外克隆性增殖的比较

为了解急性早幼粒细胞白血病(APL)患者T细胞在体内或体外经诱导后TCR Vβ亚家族的分布和克隆性增殖特点。利用T淋巴细胞液体培养法。在rhIL—2和抗CD3单抗条件下诱导扩增APL患者单个核细胞，并应用RT-PCR分别扩增培养前后患者T细胞的TCR Vβ24个亚家族基因的互补决定区3(CDR3)片段。了解各Vβ亚家族的表达情况；对阳性的PCR产物进一步经荧光素标记和基因扫描分析产物的CDR3长度。了解T细胞克隆性。结果发现，APL患者T细胞仅表达部分Vβ亚家族。但经体外培养后可检测到部分新增TCR Vβ亚家族T细胞。全部患者存在某些。TCR Vβ亚家族的克隆性增殖T细胞。2例患者均出现相似的Vβ1，Vβ3，Vβ7，Vβ16和Vβ20 T细胞的克隆性增殖情况。结论：T细胞的体外培养可诱导某些Vβ亚家族的表达。在T细胞培养不同时间中，呈持续克隆性增殖的TCR Vβ亚家族T细胞可能是患者T细胞对APL白血病细胞相关抗原的特异性免疲应答。     

Detection of a potent humoral response associated with immune-induced remission of chronic myelogenous leukemia

The effectiveness of donor-lymphocyte infusion (DLI) for treatment of relapsed chronic myelogenous leukemia (CML) after allogeneic bone marrow transplantation is a clear demonstration of the graft-versus-leukemia (GVL) effect. T cells are critical mediators of GVL, but the antigenic targets of this response are unknown. To determine whether patients who respond to DLI also develop B-cell immunity to CML-associated antigens, we analyzed sera from three patients with relapsed CML who achieved a complete molecular remission after infusion of donor T cells. Sera from these individuals recognized 13 distinct gene products represented in a CML-derived cDNA library. Two proteins, Jkappa-recombination signal-binding protein (RBP-Jkappa) and related adhesion focal tyrosine kinase (RAFTK), were recognized by sera from three of 19 DLI responders. None of these antigens were recognized by sera from healthy donors or patients with chronic graft-versus-host disease. Four gene products were recognized by sera from CML patients treated with hydroxyurea and nine were detected by sera from CML patients who responded to IFN-alpha. Antibody titers specific for RAFTK, but not for RBP-Jkappa, were found to be temporally associated with the response to DLI. These results demonstrate that patients who respond to DLI generate potent antibody responses to CML-associated antigens, suggesting the development of coordinated T- and B-cell immunity. The characterization of B cell-defined antigens may help identify clinically relevant targets of the GVL response in vivo.     

慢性粒细胞白血病患者外周血初始T细胞水平和T细胞受体Vβ谱系利用特点

目的了解慢性粒细胞白血病(CML)患者外周血初始(naive)T细胞的水平和T细胞受体(TCR)Vβ基因谱系利用和克隆性,从而了解CML患者的胸腺近期输出功能和TCRVβ亚家族T细胞增殖情况。方法采用实时定量PCR(TaqMan)方法检测20例CML患者外周血单个核细胞中T细胞受体重排删除环(Tcellreceptorrearrangementexcisioncircles,TREC)的水平,并根据外周血中CD3阳性率计算CD3+细胞中TREC水平。利用逆转录PCR和基因扫描分析其中14例患者外周血单个核细胞的TCRVβ24个亚家族基因表达和克隆性。9名正常人外周血作为对照。结果CML患者外周血TREC含量(0.06±0.16/1000CD3+细胞)明显低于正常人(6.84±4.71/1000CD3+细胞,P<0.01)。14例CML患者外周血T细胞表达不同数量Vβ亚家族(1～12个),其中13例CML患者外周血中的一些Vβ亚家族出现克隆性T细胞,Vβ3,Vβ10,Vβ19,Vβ21和Vβ22亚家族的克隆性增殖多见。结论CML患者胸腺近期输出初始T细胞功能明显降低,但仍存在优势利用和克隆性增殖Vβ亚家族T细胞,提示尽管整体T细胞免疫功能低下,但对白血病细胞相关抗原仍具有一定特异性免疫反应的能力。     

异基因造血干细胞移植患者外周血TCR Vβ亚家族克隆性增殖动态变化及其与GVHD的关系

本研究观察异基因造血干细胞移植（allo-HSCT）患者外周血T细胞受体（TCR）Vβ亚家族克隆性增殖的动态变化,分析T细胞的克隆性演变与GVHD的关系。利用RT-PCR方法扩增70例次allo-HSCT后患者（其中17例次出现GVHD）外周血单个核细胞中24个TCRVβ基因的互补决定区3（CDR3）,PCR产物经荧光标记和基因扫描分析CDR3长度,确定T细胞的克隆性。结果表明：移植患者T细胞增殖一般都经历由单克隆向多克隆演变的过程,在移植后60-90天时,逐渐由单克隆转为单克隆和多克隆表达大致各占一半。120天以后,无GVHD患者大多转为多克隆性表达;而GVHD患者受免疫抑制剂和GVHD的影响,直到1年以上仍有部分呈单克隆表达趋势。GVHD患者发生GVHD或靶器官受累最明显的时候,外周血TCRVβ亚家族的表达主要呈现单/双克隆的表现,而经过免疫抑制治疗病情好转后,部分患者出现由寡克隆表达转为多克隆增殖趋势。结论：移植后早期患者尤其是合并GVHD的患者,T细胞呈克隆性增殖和T细胞受体的倾向性利用;随着造血和免疫的恢复,TCRVβ亚家族表达重新恢复趋向正常的多克隆性演变。     

急性髓系白血病患者外周血T细胞TCR Vβ亚家族表达及克隆性增殖分析

本研究探讨AML患者在初发、治疗缓解后、复发等不同疾病状态下外周血T细胞TCRVB亚家族表达及T细胞克隆性增殖的情况,分析不同白血病细胞负荷对患者外周血T淋巴细胞数量及功能．尤其是对抗白血病功能的影响。应用RT-PCR扩增11例AML白血病患者不同疾病状态下及3名正常供者外周血的TCRBV24个家族的基因序列,通过基因扫描（genescan）的方法判断TCRBV家族的克隆表达、CDR3克隆性质,比较不同疾病状态下白血病患者外周血T细胞的Vβ亚家族的应用、克隆性增殖、T细胞的复杂性以及T细胞免疫表型的变化。结果表明：11例AML白血病患者初诊时外周血T细胞均表达部分TCR Vβ亚家族,经体外诱导后TCR Vβ亚家族表达增加;完全缓解期患者外周血T细胞TCRVβ亚家族数量明显增多,但未达到完全正常;4例患者在复发时TCR Vβ亚家族表达数量明显下降;11例患者中有9例在初诊时外周血有1至2个TCR Vβ亚家族T细胞克隆性增殖,缓解期克隆性增殖的Vβ亚家族T细胞有增加趋势,在多数病例观察到部分Vβ亚家族T细胞在初发、缓解、体外诱导扩增以及复发时仍维持克隆性增殖状态;AML白血病患者初发及复发时T细胞CDR3复杂性明显降低,呈偏态分布,而疾病缓解时T细胞复杂性有所改善。结论：AML白血病患者外周血T细胞TCR Vβ亚家族呈限制性表达;在大多数病例中无论是疾病初发抑或缓解及体外诱导、甚至在疾病复发时均可观察到克隆性T细胞的存在;在部分病例中某些Vβ亚家族在上述不同疾病状态下始终维持克隆性增殖状态,部分Vβ亚家族的克隆性增殖同白血病细胞的存在相关;在疾病状态下,AML白血病患者外周血T细胞的复杂性有所降低,而疾病缓解后可部分恢复。     

Clinical study on the relapsd leukemia patients with graft versus host disease after allogeneic hematopoietic stem cell transplantation

OBJECTIVE: To explore the dissociation of graft-versus-leukemia (GVL) effects from graft-versus-host disease (GVHD) in the patients who experienced GVHD during leukemia relapse after allogeneic hematopoietic stem cell transplantation (allo-HSCT). METHODS: The primary disease, disease status, GVHD, response to donor lymphocyte infusion (DLI) and prognosis were analysed in 11 leukemia patients who relapsed with GVHD after allo-HSCT. RESULTS: Of the 11 relapsed, 5 were acute lymphoblastic leukemia and 6 acute myeloid leukemia. Five received DLI before relapse and all developed post-DLI GVHD, including 2 grade II acute GVHD (aGVHD), 1 limited chronic GVHD (cGVHD) plus grade II aGVHD, and 2 extensive cGVHD. After relapse of the 5 patients, 2 received Chemo-DLI, one achieved CR with extensive cGVHD and then relapsed again, the other didn't achieved CR. The other 6 patients didn't received DLI before relapse and also developed post-HSCT GVHD while relapsing, including 3 extensive cGVHD, 1 grade I aGVHD and 2 grade II-IV aGVHD. After relapse, these 6 patients received Chemo-DLI, 2 achieved CR and then relapsed again, 4 didn't achieved CR. CONCLUSION: The elicited GVHD after allo-HSCT may not accompany effective GVL effects inhibiting leukemic relapse.     

Retrovirus-mediated gene transfer in primary T lymphocytes: influence of the transduction/selection process and of ex vivo expansion on the T cell receptor beta chain hypervariable region repertoire

We have initiated a phase I/II clinical trial, involving the use of herpes simplex thymidine kinase gene (HS-tk)-expressing donor primary T cells, in order to modulate the graft-versus-host disease (GvHD) occurring after allogeneic hematopoietic stem cell transplantation. The preparation of gene-modified T cells (TkTCs) required a 12-day ex vivo culture comprising an initial OKT3 and IL-2 stimulation, a retrovirus-mediated transduction, and a 7-day selection step in the presence of G418 and IL-2. The low transduction efficiency as well as the culture conditions may significantly alter the diversity of the T cell repertoire. We therefore examined the T cell repertoire of HS-tk-expressing T cell samples from 11 different donors by the Immunoscope method. This method analyzes the hypervariable region of the T cell receptor beta chain (TCRBV) by amplifying the complementarity-determining region 3 (CDR3) and determining size diversity. In all examined samples (four of which were infused into patients), all TCRBV subfamilies were represented with, however, a significant skewing within a minority of subfamilies. Kinetic studies demonstrated that this skewing appeared between day 7 and day 12, with dates of appearance variable from one subfamily to another. In addition, the repertoire analysis of two different culture products, harvested and produced at different times from the same donors, suggested that some repertoire abnormalities could be donor specific. Quantitative analysis revealed no major modifications in gene usage, even in skewed TCRBV subfamilies, with a few clonal expansions concerning a limited number of TCRBV subfamilies. Importantly, identical abnormalities were found in control cells grown in parallel under similar conditions but not transduced or selected, thus demonstrating that these abnormalities were not related to the transduction or the selection process, but rather to the ex vivo culture. The initial stimulus used for T cell activation is a major source of TCRBV perturbation, since replacing the OKT3 + IL-2 stimulus by CD3 + CD28 monoclonal antibody-coated beads prevented the occurrence of alterations. Overall, the HS-tk-expressing T cells used in our clinical trial exhibit limited TCR repertoire skewing that is not due to the transduction/selection procedure. However, future T cell gene transfer protocols for clinical trials should be designed to take into account or possibly prevent such T cell repertoire alterations.     

Ph+和Ph-CML病人外周血TCR Vβ T细胞分布特点

为了解Ph^ 和Ph^-慢性粒细胞白血病（CML）病人外周血TCR Vβ亚家族T细胞的分布特点，利用RT－PCR分别扩增13例CML病人（Ph^ -b3a2型5例，Ph^ -b2a2型5例，Ph^-型3例）外周血单个核细胞的TCR Vβ的24个亚家族基因片段，了解病人各Vβ亚家族的利用情况。研究结果：发现与正常人有所不同，病人仅存在部分TCR Vβ亚家族T细胞，Ph^ -b3a2型CML表达4－16（平均10．2）个Vβ亚家族，Ph^ -b2a2型CML表达8－11（平均8．8）个Vβ亚家族，而Ph^-者表达506（平均5．7）个Vβ亚家族。各病人表达的Vβ亚家族分布有所不同，在Ph^ (b3a2型）全部病人表达Vβ10和Vβ16，其次为Vβ9和Vβ22；Ph^ （b2a2型）除与Ph^ (b3a2型）相同全部病人表达Vβ10和Vβ16外，还全部表达Vβ24，其次为Vβ8；而Ph^-者全部表达Vβ24，其次为Vβ3，Vβ10，Vβ13和Vβ22。结论：提示Ph^ 和Ph^-CML病人外周血的TCR Vβ亚家族T细胞存在倾斜性分布现象，不同类型CML病人T细胞的TCR Vβ选择性利用有所不同，这可能与CML细胞相关抗原的差异以及个体特异性免疫反应的差异有关。     

bcr3-ab12多肽诱导脐血T细胞受体Vβ亚家族T细胞克隆性增殖的研究

目的　了解bcr3 abl2多肽诱导T细胞受体 (TCR)Vβ亚家族T细胞克隆性增殖情况。 方法　以人工合成bcr3 abl2多肽联合IL 2 抗CD3单克隆抗体 (单抗 )诱导脐血T细胞增殖 ,运用RT PCR 基因扫描技术分析其TCRVβ亚家族的利用和克隆性特点。结果　bcr3 abl2多肽成功诱导 3份脐血单个核细胞 (MNC)产生多肽特异T细胞。bcr3 abl2多肽和CD3单抗 IL 2均可诱导脐血T细胞扩增 ,多肽诱导的新增Vβ亚家族表达与不加多肽的CD3单抗 IL 2诱导组的T细胞不完全相同。培养前和单用CD3单抗 IL 2诱导后的T细胞绝大多数为多克隆性 ,而bcr3 abl2多肽诱导 1周或 2周后 ,分别在 3例脐血中诱导出寡克隆增殖和呈寡克隆增殖趋势T细胞。结论　bcr3 abl2多肽可在体外诱导出抗慢性粒细胞白血病细胞的脐血特异性细胞毒性T淋巴细胞 (CTL) ,该CTL作用可能是由优势表达的Vβ亚家族克隆性T细胞所介导。     

异基因造血干细胞移植后白血病复发伴活动性移植物抗宿主病患者的临床研究

目的 探讨异基因造血干细胞移植(allo-HSCT)后白血病复发伴活动性移植物抗宿主病(GVHD)患者GVHD与GVL效应的分离.方法 分析11例接受allo-HSCT后在白血病复发时存在活动性GVHD的患者其原发病、疾病状态、复发时GVHD类型、供者淋巴细胞输注(DLI)疗效及转归等对GVL效应的影响.结果 11例患者包括急性淋巴细胞白血病5例,急性髓系白血病6例,其中5例曾行预防性DLI,复发时伴有活动性DLI后GVHD,包括2例Ⅱ度急性GVHD(aGVHD),1例原局限型慢性GVHD(cGVHD)加重+新发Ⅱ度aGVHD,2例广泛型cGVHD;这5例患者复发后,2例行化疗+治疗性DLI,DLI后在广泛型cGVHD反复加重情况下,1例达完全缓解(CR)后再次复发,1例未达CR.另6例患者复发前未行预防性DLI,白血病复发时亦均存在活动性GVHD,包括3例广泛型cGVHD、1例Ⅰ度aGVHD及2例Ⅲ～Ⅳ度aGVHD,复发后行化疗+治疗性DLI,之后2例达CR后再次复发,4例未达CR.结论 allo-HSCT后活动性GVHD不一定伴随可抑制白血病复发的有效GVL效应.     

Adoptive allogeneic immunotherapy--history and future perspectives

For more than 30 yrs allogeneic hematopoietic stem cell transplantations have been successfully performed in patients with hematologic malignancies and bone marrow aplasia. Over the years the field of transplantation has changed dramatically. More and more unrelated donors became available, regimens for haploidentical transplantations were introduced and G-CSF mobilized peripheral blood stem cells and fetal cells from umbilical cord became available as alternate sources of hematopoietic stem cells. However, especially the introduction of donor lymphocyte infusions (DLI) for the successful treatment of leukemic relapses after allogeneic stem cell transplantations improved our understanding of transplantation immunology and opened amazing perspectives in allogeneic transplantation. It was long believed, that myeloablative therapy with high-dose chemotherapy and total body irradiation (TBI) are the sole antileukemic principles in allogeneic transplantations. But by now it became clear, that donor lymphocytes exert a very potent antileukemic effect, now referred as the graft-versus-leukemia (GVL) or graft-versus-malignancy (GVM) reaction. The efficacy of DLI in controlling leukemic relapses suggests that myeloablative therapy is not essential for long-term disease control. By exploiting the GVL or GVM reaction more intensively the role of chemotherapy and TBI is changing to immunosuppression. Sufficient immunosuppression to allow grafting, however, can be achieved with much lower doses as those which have been used in conventional transplants. Therefore allogeneic transplants have become also available for the elderly or for patients with concurrent medical conditions, which would have excluded them from conventional transplants. Moreover, this allogeneic transplantation strategy with reduced intensity conditioning is now also under investigation in patients with susceptible solid tumors and autoimmune diseases. However, one major obstacle in allogeneic transplantations, namely the graft-versus-host disease (GVHD), remains to be solved.     

Differential roles of IL-1 and TNF-α on graft-versus-host disease and graft versus leukemia

We demonstrate an increase in graft-versus-host disease (GVHD) after experimental bone marrow transplant (BMT) when cyclophosphamide (Cy) is added to an otherwise well-tolerated dose (900 cGy) of total body irradiation (TBI). Donor T cell expansion on day +13 was increased after conditioning with Cy/TBI compared with Cy or TBI alone, although cytotoxic T lymphocyte (CTL) function was not altered. Histological analysis of the gastrointestinal tract demonstrated synergistic damage by Cy/TBI and allogeneic donor cells, which permitted increased translocation of LPS into the systemic circulation. TNF-alpha and IL-1 production in response to LPS was increased in BMT recipients after Cy/TBI conditioning. Neutralization of IL-1 significantly reduced serum LPS levels and GVHD mortality, but it did not affect donor CTL activity. By contrast, neutralization of TNF-alpha did not prevent GVHD mortality but did impair CTL activity after BMT. When P815 leukemia cells were added to the bone marrow inoculum, allogeneic BMT recipients given the TNF-alpha inhibitor relapsed at a significantly faster rate than those given the IL-1 inhibitor. To confirm that the role of TNF-alpha in graft versus leukemia (GVL) was due to effects on donor T cells, cohorts of animals were transplanted with T cells from either wild-type mice or p55 TNF-alpha receptor-deficient mice. Recipients of TNF-alpha p55 receptor-deficient T cells demonstrated a significant impairment in donor CTL activity after BMT and an increased rate of leukemic relapse compared with recipients of wild-type T cells. These data highlight the importance of conditioning in GVHD pathophysiology, and demonstrate that TNF-alpha is critical to GVL mediated by donor T cells, whereas IL-1 is not.     

Donor regulatory T cells identified by FoxP3 expression but also by the membranous CD4+CD127low/neg phenotype influence graft-versus-tumor effect after donor lymphocyte infusion

Regulatory T cells (Treg) play a pivotal role in the control of graft-versus-host disease (GVHD) and might also influence the graft-versus-tumor effect after allogeneic stem cell transplantation. We assessed this role after donor lymphocyte infusions (DLIs) by quantifying Treg in DLI products, using the CD25, Foxp3 but also the recently identified CD127 Treg markers. Compared with others, patients in durable complete remission of their malignancy after DLI had received a lower number of FoxP3CD25, FoxP3CD127, or CD4CD127 Treg cells (P=0.04). The CD4CD127 Treg content of DLI remained significantly correlated with the hematologic response in multivariate analysis (P=0.05). Treg may thus inhibit graft-versus-tumor effect after DLI, a setting where the antitumoral effect observed is only driven by T-cell-mediated cytotoxicity, independently of any other associated treatment. In comparison with the intracytoplasmic Foxp3 marker, the membranous CD4CD127 phenotype of Treg could be particularly relevant to manipulate this cell-population, to increase the antitumoral response in strategies of allogeneic or autologous immunotherapy.     

Immunomodulatory effects of donor lymphocyte infusions following allogeneic bone marrow transplantation

Recently, donor lymphocyte infusions have been successfully used to treat patients with CML who have relapsed following allogeneic bone marrow transplantation (BMT). Responses can be achieved in more than 60–70% of patients with stable phase CML without the need for the additional high dose cytotoxic chemotherapy that would accompany a second transplant procedure. The clinical and molecular remissions induced by this approach are a clear demonstration of graft-versus-leukemia (GVL) activity. Although undoubtedly donor lymphocyte infusions are safer than a second BMT, they are associated with toxicities stemming from graft-versus-host disease (GVHD) and pancytopenia. In this review, the immunomodulatory mechanisms underlying the GVL activity of donor allogeneic lymphocytes infusions are presented. Unresolved issues regarding lymphocyte administration are discussed as well as potential ways to limit complications due to GVHD and pancytopenia. New potential applications of this immunotherapeutic approach for treatment of infectious disease and non-hematologic malignancies will be presented.     

NKT cell-dependent leukemia eradication following stem cell mobilization with potent G-CSF analogs

NKT cells have pivotal roles in immune regulation and tumor immunosurveillance. We report that the G-CSF and FMS-like tyrosine kinase 3 ligand (Flt-3L) chimeric cytokine, progenipoietin-1, markedly expands the splenic and hepatic NKT cell population and enhances functional responses to alpha-galactosylceramide. In a murine model of allogeneic stem cell transplantation, donor NKT cells promoted host DC activation and enhanced perforin-restricted CD8+ T cell cytotoxicity against host-type antigens. Following leukemic challenge, donor treatment with progenipoietin-1 significantly improved overall survival when compared with G-CSF or control, attributable to reduced graft-versus-host disease mortality and paradoxical augmentation of graft-versus-leukemia (GVL) effects. Enhanced cellular cytotoxicity was dependent on donor NKT cells, and leukemia clearance was profoundly impaired in recipients of NKT cell-deficient grafts. Enhanced cytotoxicity and GVL effects were not associated with Flt-3L signaling or effects on DCs but were reproduced by prolonged G-CSF receptor engagement with pegylated G-CSF. Thus, modified G-CSF signaling during stem cell mobilization augments NKT cell-dependent CD8+ cytotoxicity, effectively separating graft-versus-host disease and GVL and greatly expanding the potential applicability of allogeneic stem cell transplantation for the therapy of malignant disease.     

[18F]FHBG PET/CT Imaging of CD34-TK75 Transduced Donor T Cells in Relapsed Allogeneic Stem Cell Transplant Patients: Safety and Feasibility

Described herein is a first-in-man attempt to both genetically modify T cells with an imagable suicide gene and track these transduced donor T cells in allogeneic stem cell transplantation recipients using noninvasive positron emission tomography/computerized tomography (PET/CT) imaging. A suicide gene encoding a human CD34-Herpes Simplex Virus-1-thymidine kinase (CD34-TK75) fusion enabled enrichment of retrovirally transduced T cells (TdT), control of graft-versus-host disease and imaging of TdT migration and expansion in vivo in mice and man. Analysis confirmed that CD34-TK75-enriched TdT contained no replication competent γ-retrovirus, were sensitive to ganciclovir, and displayed characteristic retroviral insertion sites (by targeted sequencing). Affinity-purified CD34-TK75⁺-selected donor T cells (1.0–13 × 10⁵)/kg were infused into eight patients who relapsed after allogeneic stem cell transplantation. Six patients also were administered 9-[4-(¹⁸F)fluoro-3-hydroxymethyl-butyl]guanine ([¹⁸F]FHBG) to specifically track the genetically modified donor T cells by PET/CT at several time points after infusion. All patients were assessed for graft-versus-host disease, response to ganciclovir, circulating TdT cells (using both quantitative polymerase chain reaction and [¹⁸F]FHBG PET/CT imaging), TdT cell clonal expansion, and immune response to the TdT. This phase 1 trial demonstrated that genetically modified T cells and [¹⁸F]FHBG can be safely infused in patients with relapsed hematologic malignancies after allogeneic stem cell transplantation.     

Evolution of antigen-specific T cell receptors in vivo: preimmune and antigen-driven selection of preferred complementarity-determining region 3 (CDR3) motifs.

Antigen (Ag)-driven selection of helper T cells (Th) in normal animals has been difficult to study and remains poorly understood. Using the major histocompatibility complex class II- restricted murine response to pigeon cytochrome c (PCC), we provide evidence for both preimmune and Ag-driven selection in the evolution of Ag-specific immunity in vivo. Before antigenic challenge, most Valpha11(+)Vbeta3(+) Th (70%) express a critical complementarity-determining region 3 (CDR3) residue (glutamic acid at TCR-alpha93) associated with PCC peptide contact. Over the first 5 d of the primary response, PCC-responsive Valpha11(+)Vbeta3(+) Th expressing eight preferred CDR3 features are rapidly selected in vivo. Clonal dominance is further propagated through selective expansion of the PCC-specific cells with T cell receptor (TCR) of the "best fit." Ag-driven selection is complete before significant emergence of the germinal center reaction. These data argue that thymic selection shapes TCR-alpha V region bias in the preimmune repertoire; however, Ag itself and the nongerminal center microenvironment drive the selective expansion of clones with preferred TCR that dominate the response to Ag in vivo.     

PKCθ is required for alloreactivity and GVHD but not for immune responses toward leukemia and infection in mice

When used as therapy for hematopoietic malignancies, allogeneic BM transplantation (BMT) relies on the graft-versus-leukemia (GVL) effect to eradicate residual tumor cells through immunologic mechanisms. However, graft-versus-host disease (GVHD), which is initiated by alloreactive donor T cells that recognize mismatched major and/or minor histocompatibility antigens and cause severe damage to hematopoietic and epithelial tissues, is a potentially lethal complication of allogeneic BMT. To enhance the therapeutic potential of BMT, we sought to find therapeutic targets that could inhibit GVHD while preserving GVL and immune responses to infectious agents. We show here that T cell responses triggered in mice by either Listeria monocytogenes or administration of antigen and adjuvant were relatively well preserved in the absence of PKC isoform θ (PKCθ), a key regulator of TCR signaling. In contrast, PKCθ was required for alloreactivity and GVHD induction. Furthermore, absence of PKCθ raised the threshold for T cell activation, which selectively affected alloresponses. Most importantly, PKCθ-deficient T cells retained the ability to respond to virus infection and to induce GVL effect after BMT. These findings suggest PKCθ is a potentially unique therapeutic target required for GVHD induction but not for GVL or protective responses to infectious agents.