Phenotype and functional evaluation of ex vivo generated antigen-specific immune effector cells with potential for therapeutic applications
© Han et al; licensee BioMed Central Ltd. 2009
Received: 30 June 2009
Accepted: 6 August 2009
Published: 6 August 2009
Ex vivo activation and expansion of lymphocytes for adoptive cell therapy has demonstrated great success. To improve safety and therapeutic efficacy, increased antigen specificity and reduced non-specific response of the ex vivo generated immune cells are necessary. Here, using a complete protein-spanning pool of pentadecapeptides of the latent membrane protein 2A (LMP2A) of Epstein-Barr virus (EBV), a weak viral antigen which is associated with EBV lymphoproliferative diseases, we investigated the phenotype and function of immune effector cells generated based on IFN-γ or CD137 activation marker selection and dendritic cell (DC) activation. These ex vivo prepared immune cells exhibited a donor- and antigen-dependent T cell response; the IFN-γ-selected immune cells displayed a donor-related CD4- or CD8-dominant T cell phenotype; however, the CD137-enriched cells showed an increased ratio of CD4 T cells. Importantly, the pentadecapeptide antigens accessed both class II and class I MHC antigen processing machineries and effectively activated EBV-specific CD4 and CD8 T cells. Phenotype and kinetic analyses revealed that the IFN-γ and the CD137 selections enriched more central memory T (Tcm) cells than did the DC-activation approach, and after expansion, the IFN-γ-selected effector cells showed the highest level of antigen-specificity and effector activities. While all three approaches generated immune cells with comparable antigen-specific activities, the IFN-γ selection followed by ex vivo expansion produced high quality and quantity of antigen-specific effector cells. Our studies presented the optimal approach for generating therapeutic immune cells with potential for emergency and routine clinical applications.
The key to the success of immune cell therapy is to increase specific and decrease non-specific immune response. Ex vivo expanded antigen-specific T cells targeting cytomegalovirus (CMV), Epstein-Barr virus (EBV) and adenovirus have been successfully applied to treating hematopoietic stem cell or solid organ transplant patients who have developed post-transplant viral diseases. [1, 2] The labor-intensive and time-consuming process of isolating and expanding antigen-specific immune cells, however, has hindered common practice of this medical advent.
Donor leukocyte infusion has attained a response rate of >50% in treating post-transplant infections or cancer relapse of hematopoietic stem cell transplant (HSCT) patients. [3–5] Non-specific leukocyte infusion, however, may cause severe graft-versus-host disease (GvHD) with high morbidity and mortality. Adoptive transfer of antigen-specific T cell clones combined with clinical regimens to increase immune cell homeostasis has illustrated high response rate (50%) in melanoma patients. [6–8] While the amplified T cell clones display increased antigen-specific effector functions, the ex vivo expansion process takes longer than 4–6 weeks, which often results in terminal differentiation of the T cells with reduced in vivo proliferation potential. 
A few approaches have been developed to directly isolate antigen-specific immune cells, such as the use of MHC-peptide multimers and selection of IFN-γ-secreting cells with affinity-magnetic beads. [10–14] Recently, CD137 (4-1BB), a member of the tumor necrosis factor receptor family, has been reported to be a suitable surface marker for antigen-specific T cell isolation.  Although both the IFN-γ and the CD137 selection methods generate only a small number of immune effector cells, these cells may be further expanded in culture to obtain more functional cells. 
Detailed phenotype and functional characterizations of these ex vivo prepared immune effector cells are necessary to facilitate their clinical applications. Here, we refined and compared three of the state-of-the-art immune effector cell preparation approaches, the IFN-γ and the CD137 selection methods for emergency preparation of therapeutic cells, and a DC-immune cell coculture method for the expansion of antigen-specific immune cells. We targeted EBV using LMP2A pentadecapeptides as antigens because EBV-associated lymphoproliferative disorders represent one of the most severe problems in HIV/AIDS patients and transplantation patients. The IFN-γ-selected cells showed an increased ratio of CD4 or CD8 effector cell population depending on the donor, whereas the CD137 selection method enriched a higher ratio of CD4 T cells regardless of the donor's T cell dominance response. Both of the rapid protocols yielded more central memory and effector memory T cells than did the DC-activation method. Our detailed side-by-side comparison concludes that IFN-γ selection followed by ex vivo expansion represents the preferred method for the generation of antigen-specific immune effector cells with potential for clinical applications.
Peripheral blood mononuclear cells (PBMC) and B lymphoblastoid cell lines (BLCL)
Healthy donors' buffy coats were obtained from Civitan Blood Center (Gainesville, FL, USA). PBMC were prepared by gradient density centrifugation in Ficoll-Hypaque (GE Healthcare Bio-Sciences AB, NJ, USA) as previously described.  Viability was determined by trypan blue staining. Autologous B lymphoblastoid cell line (BLCL) was generated by transforming peripheral blood B lymphocytes with EBV as described previously.  The BLCL were continuously propagated in RPMI 1640 medium supplemented with 2 mM L-glutamine, 100 μg/ml streptomycin, 100 IU/ml penicillin and 10% heat inactivated fetal bovine serum (FBS) at 37°C with 5% CO2.
The mixtures of 11 amino acid overlapping pentadecapeptides (122 peptides) spanning the entire 497 amino acids (NCBI Accession number P13285) of LMP2A of the EBV (human herpesvirus 4, strain B95-8) and the Wilms' tumor antigen (WT1, 449 amino acids, 110 peptides) were purchased from JPT Peptide Technologies GmbH (Berlin, Germany).
Preparation of 2 day and 5 day dendritic cells (DC)
PBMC were plated into 6-well plate at 1 × 107 cells/well and adhered for 2 hours in AIM-V (Gibco-BRL, CA, USA). The non-adherent cells were removed gently and frozen as source of lymphocytes for co-culture use. Adherent monocytes were cultured in AIM-V supplemented with 50 ng/ml of GM-CSF and 25 ng/ml IL-4 (eBiosource International, Inc. Camarillo, CA, USA). For the generation of 2 day DC, the adherent cells were cultured with GM-CSF and IL-4 for 24 h and incubated for another 24 h with TNFα (50 ng/ml), IL-1β (10 ng/ml), IL-6 (10 ng/ml, all from R&D systems, MN, USA) and PGE2 (1 uM, Sigma-Aldrich, MO, USA) to induce maturation. For the generation of 5 day DC, cells were cultured with GM-CSF and IL-4 for 5 days. On day 3, half of the medium was replaced with fresh medium containing GM-CSF and IL-4. On day 5, the immature DC were induced into maturation with TNFα (50 ng/ml), LPS (1 μg/ml, Sigma-Aldrich) and IFN-γ (50 ng/ml, R&D systems).
Isolation of antigen-specific IFN-γ secreting or CD137 positive cells
PBMC were resuspended in AIM-V plus 5% human AB serum at 1 × 107 cells/ml and mixed with pentadecapeptides for EBV-LMP2A (10 ug/ml), mouse anti-human CD28 antibody (Ab, 1 ug/ml, eBioscience, San Diego, USA) and human β2-microglobulin (1 ug/ml, Sigma) to enhance antigen presentation and costimulation. The cells were incubated in a 37°C humidified incubator for 3–13 hours. IFN-γ secreting cells were enriched with the IFN-γ Catch Reagent and CD137 positive cells with PE-conjugated monoclonal anti-CD137 Ab (clone 4B4-1), followed by affinity isolation using anti-PE microbeads according to the manufacturer's instruction (Miltenyi Biotech Inc. Auburn, CA, USA).
Generation of DC-activated antigen-specific immune cells
DC-activated antigen-specific immune cells were generated as previously described.  In brief, mature 2 day DC were loaded with LMP2A peptides (2.5 ug/ml) for 2 h and irradiated (20 Gy, or 2,000 rads). The antigen-pulsed DC were cocultured with autologous non-adherent PBMC at a ratio of 1:20 in AIM-V with 5% human AB serum. On day 3, half of the medium was replaced with fresh medium supplemented with IL-2 (12.5 U/ml), IL-7 (5 ng/ml) and IL-15 (20 ng/ml, all from Gentaur, Aachen, Germany). Half of the medium was replaced with fresh medium with cytokines every other day.
Multi-color flow cytometry
Mature DC were analyzed using a four-color panel of monoclonal Ab including PE-anti-CD14, FITC-anti-HLA-DR, PE-anti-CD86, APC-anti-CD1a, PE-anti-CD 83, APC-anti-CD40 and FITC-anti-HLA-I (BD Biosciences, San Jose, CA, USA), APC-anti-DC-SIGN and PE-cy7-anti-CD11c (eBioscience), and incubated for 30 min at 4°C. Isotype-matched antibodies were used for controls. The Ab-labeled cells were washed twice with PBS containing 1% FBS and analyzed with FACSCaliber or FACSAria using FACSDiva software (BD Biosciences) and Flowjo software (Tree Star, Inc., Ashland, OR, USA). For memory T cell analysis, the cells were stained with PE-anti-IFN-γ or PE-anti-CD137, in combination with APC-anti-CD4 (clone RPA-T4), Pacific blue-anti-CD8 (clone RPA-T8), FITC-anti-CD45RA (clone HI100), PE-cy7-anti-CCR7 (clone 3D12), Percp-cy5.5-anti-CD28 (clone 293, all from BD Biosciences) and Alexa-fluo 750-anti-CD27 (clone O323, eBioscience) at 4°C for 30 min and washed twice with PBS containing 1% FBS. The percentage of different T cell subsets was analyzed using FACSAria with FACSDiva and Flowjo softwares.
Immune effector assays: CD107a degranulation and intracellular cytokine staining
These assay were performed as described.  Briefly, 2 × 105 LMP2A-specific T cells were stimulated for 5 h in a 96-well plate with irradiated (20 Gy) antigen-loaded autologous DC. Monensin A (Sigma-Aldrich) and FITC-conjugated Abs for CD107a or isotype matched Abs (BD Pharmingen, San Diego, CA, USA) were added 1 hour after stimulation and incubated for 5 hours. Cells were then stained with Abs against CD4 and CD8 and fixed, permeabilized with Cytofix/Cytoperm solution and stained with Ab against IFN-γ (all from BD Pharmingen) at 4°C for 20 min. Unrelated peptide group was included as a negative control for spontaneous CD107a expression and/or cytokine production.
Detection of peptide-specific CD8+ T cells by MHC multimer analysis
Peptide-major histocompatibility complex (MHC)-pentamer conjugate specific for EBV-LMP2A/TYGPVFMCL (HLA-A*2402 restricted) was purchased from Proimmune (Springfield, VA, USA). T cells were incubated with PE-labeled peptide MHC-pentamer at room temperature for 10 min, washed and stained with APC-anti-CD3 and FITC-anti-CD8 Ab (BD Pharmingen) on ice for 30 min, and analyzed using FACSAria. At least 1 × 105 events were collected for each sample.
T cell proliferation assay with carboxy-fluorescein diacetate succinimidyl ester (CFSE) staining
The CFSE-based proliferation assay was performed as previously described . Briefly, LMP2A-specific T cells were washed and labeled with 1 uM CFSE (Molecular Probes, Inc., Eugene, OR, USA). The labeled cells were washed and plated into 96-well U-bottom wells at 1 × 105 cells per well. Autologous DC were loaded with peptides (2.5 ug/ml) for 2 hours and irradiated (20 Gy). The irradiated DC were added to the CFSE-labeled T cells at a ratio of 1:20 and cultured in AIM-V with 5% human AB serum. After 4 days, cells were harvested and analyzed with flow cytometry.
Antigen-specific cytotoxicity assay of immune effector cells
(R refers to different CTL ratio groups; R = 0 refers to the CTL = 0 control)
Data were analyzed using GraphPad Prism 4 analysis software (GraphPad Software Inc. San Diego, CA) and Student's t-test. A 2-sided P value of less than 0.05 was considered statistically significant.
Both IFN-γ and CD137 are effective markers for the isolation of antigen-specific immune effector cells
The antigen-activated IFN-γ and CD137 positive immune cells display different surface phenotypes
Ex vivo expansion of antigen-activated IFN-γ and CD137 positive immune cells
Ex vivo expansion of antigen-specific immune effector cells with dendritic cells (DC)
The DC-activated immune cells display antigen-specific effector functions
To demonstrate antigen-specific killing, we directly compared the DC-activated cells to the IFN-γ captured cells (as shown in Fig. 4C) using an in vitro cytolytic assay (Fig. 8B). At an effector to target cell ratio of 1:1, the immune cells effectively killed autologous BLCL and LMP2A-pulsed DC (DC-LMP2A), but not DC pulsed with control WT1 pentadecapeptides (DC-WT1). Therefore, effector function analyses including IFN-γ release and cytotoxicity assays suggest that the DC-activated cells had lower activities than the expanded IFN-γ effector cells.
Adoptive immune cell therapy has shown great promise in treating viral diseases and melanoma. [2, 6] Continued efforts are focused on the generation of sufficient amount of antigen-specific immune cells and optimal conditioning of immune homeostasis in patients in order to achieve a sustained in vivo immune surveillance. [24–26] Here, we compared three ex vivo immune cell preparation protocols and phenotypically and functionally characterized these cells. The rapid protocols based on IFN-γ and CD137 selection generate a small number of antigen-specific effector cells with high percentage of central memory T cells in a very short period of time. The DC-activation protocol generates more immune cells, albeit, with more differentiated phenotype and reduced proportion of antigen-specific effector cells.
Based on analyses of a large number of donors, we found that individual response to a given antigen could be either CD4- or CD8-dominant, which is antigen- and donor-dependent. Immune effector cells isolated based on IFN-γ expression displayed a CD4 or CD8 bias consistent with the donor's immune dominance. However, antigen-specific CD137 positive cells showed a higher ratio of CD4 effector cells regardless of the subject's immune phenotype; this is in contrast to previous reports that emphasize the induction of CD8 effector cells after CD137 enrichment. [15, 22, 27] We did, however, show that CD8 T cells displayed higher density of CD137 than did CD4 T cells. It is well documented that CD137 costimulation promotes both CD4 and CD8 T cell expansion and long term memory. [28–30] Our finding that more CD4 T cells than CD8 T cells are detected in the CD137-positive cell population suggests a rapid induction of CD137 in the memory T helper repertoire immediately after antigen stimulation. Although the enriched CD137 immune cells contained a higher CD4 T cell ratio, further expansion in culture restored the donor's original dominant phenotype, with a higher CD3-CD56+ NK cell population than those found in the expanded IFN-γ enriched immune cells (Fig. 3A). This result suggests that IFN-γ is a more restricted adoptive immune response marker and represent less of an innate immune marker as does CD137.
The ex vivo DC-activation protocol generated different ratios of CD4, CD8 and NK cells in culture, which again, appeared to be donor-dependent. Whether the immune dominance has any effect on in vivo efficacy of the cultured immune effector cells awaits further investigation. As CD4 T cells are important for the maintenance of long-term anti-viral CD8 T cell memory , therapeutic immune cells should include polyclonal CD4 and CD8 T cells. Both IFN-γ and CD137 selection approaches generated increased number of memory type of cells representative of polyclonal CD4 and CD8 T cells that may have increased proliferation potential after infusion. Although the antigen-specific memory T cells from PBMC may be low; for examples, the average yield of LMP2A-specific IFN-γ positive immune effector cells from healthy EBV-seropositive donors is only 0.22 ± 0.13% (n = 6, after two rounds of affinity column purification), they can be expanded to more than two orders of magnitude in culture in two weeks and maintain their high antigen specificity.
It is evident that the LMP2A pentadecapeptides efficiently activate both CD4 and CD8 T cells in a short exposure period (3–13 hr). This was surprising since CD8 T cells are activated through class I MHC loaded with short 9–11 amino acid peptide epitopes, different from CD4 T cells, which are activated through class II MHC loaded with 12–15 amino acid peptide epitopes. The pentadecapeptide antigens apparently activated CD8 T cells with high efficiency through cross-presentation. This has been confirmed with various pentadecapeptide antigens (unpublished). The processing of class II MHC peptides into class I epitopes for cross-presentation to CD8 T cells appears to be highly efficient with both the IFN-γ and the CD137 protocols, as with the DC-activation method. The detailed molecular mechanism of the efficient cross-presentation requires further investigation.
To assess differentiation and maturation status of the ex vivo generated T cells, we applied multi-color flow cytometry to detect differentiation and homeostatic marker CD45RA, trafficking marker CCR7, and costimulatory marker CD27 and CD28. [32, 33] It is not surprising that both the IFN-γ- and the CD137-enriched antigen-specific effector cells displayed more memory markers than did the DC coculture-expanded cells. While preserving Tcm cells is critical to in vivo therapeutic efficacy,[7, 34, 35] clinical studies have proven that ex vivo expanded effector cells can persist many years after infusion.  Clinical benefits of these different protocols will require detailed evaluation in a large cohort of patients.
The differentiation status of the ex vivo generated immune cells may contribute to their in vivo therapeutic efficacy. Homeostasis of antigen-specific memory cells can vary depending on antigen source, the immune milieu and individual donor. It is known that Tcm cells are mainly located in lymphoid tissues and Tem cells are distributed in diverse non-lymphoid sites including lung, liver and intestine.  In addition, bone marrow has been shown to embrace increased number of anti-cancer or anti-virus memory T cells. [38–40] After ex vivo expansion, however, wherever the T cells come from, they tend to bestow exhausted proliferation and replicative senescence associated with down-regulation of anti-apoptotic protein Bcl-2 and Bcl-xL, and decreased telomere length. [33, 34, 41] Modification of antigen presentation protocol and culture condition may help overcome the immune cell exhaustion problem. [9, 42]
For patients with acute infections or illness, direct isolation of antigen-specific immune cells from partly HLA-matched healthy donors represents an attractive emergency approach to obtain therapeutic cells. [43, 44] This approach offers several advantages including a shortened handling time and increased proliferation potential in vivo. Although the number of immune cells is limited with the direct isolation approach, clinical evidence supports that only a small number of such immune cells, in the range of 103-104/kg body weight, is sufficient to attain therapeutic efficacy in transplant patients. [13, 45, 46]Ex vivo expansion of immune cells, nevertheless, may be necessary for patients with a compromised immunity. [47, 48]
The two rapid immune cell isolation methods generate functional effector cells in less than 24–48 hr suitable for emergency immune cell preparation. On the other hand, the DC-activation method expands antigen-specific immune effector cells while effectively reduce the number of non-specific cells. Depending on clinical needs, for examples, the urgency for treatment, patient's body weight (e.g. less cells are needed for pediatric patients), or patient's immune cell proliferative potential in vivo, the method of immune cell preparation may differ. Our data indicate that IFN-γ selection followed by ex vivo expansion represents the best approach for the generation of high amount of antigen-specific immune effector cells. Further efforts to overcome immune tolerance and expand antigen-specific immune cells with prolonged in vivo persistence are critical to the success of immune cell therapy.
List of abbreviations
cytotoxic T lymphocyte
major histocompatibility complex
T cell receptor
tumor necrosis factor
B lymphoblastoid cell line
late membrane protein 2A
intracellular cytokine staining
carboxy-fluorescein diacetate succinimidyl ester.
We thank the technical assistance of Liheng Guo, Lily Lien, Fuhung Yang, Yinchieh Fu and Meifang Lin. The study was funded by Vectorite Biomedica Inc. and Yongling Foundation.
- Riddell SR, Greenberg PD: Principles for adoptive T cell therapy of human viral diseases. Annu Rev Immunol. 1995, 13: 545-586. 10.1146/annurev.iy.13.040195.002553.View ArticlePubMedGoogle Scholar
- Fujita Y, Rooney CM, Heslop HE: Adoptive cellular immunotherapy for viral diseases. Bone Marrow Transplant. 2008, 41: 193-198. 10.1038/sj.bmt.1705906.View ArticlePubMedGoogle Scholar
- Papadopoulos EB, Ladanyi M, Emanuel D, Mackinnon S, Boulad F, Carabasi MH, Castro-Malaspina H, Childs BH, Gillio AP, Small TN, Young JW, Kernan NA, O'Reilly RJ: Infusions of donor leukocytes to treat Epstein-Barr virus-associated lymphoproliferative disorders after allogeneic bone marrow transplantation. N Engl J Med. 1994, 330: 1185-1191. 10.1056/NEJM199404283301703.View ArticlePubMedGoogle Scholar
- O'Reilly RJ, Small TN, Papadopoulos E, Lucas K, Lacerda J, Koulova L: Biology and adoptive cell therapy of Epstein-Barr virus-associated lymphoproliferative disorders in recipients of marrow allografts. Immunol Rev. 1997, 157: 195-216. 10.1111/j.1600-065X.1997.tb00983.x.View ArticlePubMedGoogle Scholar
- Collins RH, Shpilberg O, Drobyski WR, Porter DL, Giralt S, Champlin R, Goodman SA, Wolff SN, Hu W, Verfaillie C, List A, Dalton W, Ognoskie N, Chetrit A, Antin JH, Nemunaitis J: Donor leukocyte infusions in 140 patients with relapsed malignancy after allogeneic bone marrow transplantation. J Clin Oncol. 1997, 15: 433-444.PubMedGoogle Scholar
- Dudley ME, Wunderlich JR, Robbins PF, Yang JC, Hwu P, Schwartzentruber DJ, Topalian SL, Sherry R, Restifo NP, Hubicki AM, Robinson MR, Raffeld M, Duray P, Seipp CA, Rogers-Freezer L, Morton KE, Mavroukakis SA, White DE, Rosenberg SA: Cancer regression and autoimmunity in patients after clonal repopulation with antitumor lymphocytes. Science. 2002, 298: 850-854. 10.1126/science.1076514.PubMed CentralView ArticlePubMedGoogle Scholar
- Gattinoni L, Powell DJ, Rosenberg SA, Restifo NP: Adoptive immunotherapy for cancer: building on success. Nat Rev Immunol. 2006, 6: 383-393. 10.1038/nri1842.PubMed CentralView ArticlePubMedGoogle Scholar
- Rosenberg SA, Restifo NP, Yang JC, Morgan RA, Dudley ME: Adoptive cell transfer: a clinical path to effective cancer immunotherapy. Nat Rev Cancer. 2008, 8: 299-308. 10.1038/nrc2355.PubMed CentralView ArticlePubMedGoogle Scholar
- Klebanoff CA, Gattinoni L, Restifo NP: CD8+ T-cell memory in tumor immunology and immunotherapy. Immunol Rev. 2006, 211: 214-224. 10.1111/j.0105-2896.2006.00391.x.PubMed CentralView ArticlePubMedGoogle Scholar
- Yee C, Savage PA, Lee PP, Davis MM, Greenberg PD: Isolation of high avidity melanoma-reactive CTL from heterogeneous populations using peptide-MHC tetramers. J Immunol. 1999, 162: 2227-2234.PubMedGoogle Scholar
- Szmania S, Galloway A, Bruorton M, Musk P, Aubert G, Arthur A, Pyle H, Hensel N, Ta N, Lamb L, Dodi T, Madrigal A, Barrett J, Henslee-Downey J, van Rhee F: Isolation and expansion of cytomegalovirus-specific cytotoxic T lymphocytes to clinical scale from a single blood draw using dendritic cells and HLA-tetramers. Blood. 2001, 98: 505-512. 10.1182/blood.V98.3.505.View ArticlePubMedGoogle Scholar
- Rauser G, Einsele H, Sinzger C, Wernet D, Kuntz G, Assenmacher M, Campbell JD, Topp MS: Rapid generation of combined CMV-specific CD4+ and CD8+ T-cell lines for adoptive transfer into recipients of allogeneic stem cell transplants. Blood. 2004, 103: 3565-3572. 10.1182/blood-2003-09-3056.View ArticlePubMedGoogle Scholar
- Feuchtinger T, Matthes-Martin S, Richard C, Lion T, Fuhrer M, Hamprecht K, Handgretinger R, Peters C, Schuster FR, Beck R, Schumm M, Lotn R, Jahn G, Lang P: Safe adoptive transfer of virus-specific T-cell immunity for the treatment of systemic adenovirus infection after allogeneic stem cell transplantation. Br J Haematol. 2006, 134: 64-76. 10.1111/j.1365-2141.2006.06108.x.View ArticlePubMedGoogle Scholar
- Mackinnon S, Thomson K, Verfuerth S, Peggs K, Lowdell M: Adoptive cellular therapy for cytomegalovirus infection following allogeneic stem cell transplantation using virus-specific T cells. Blood Cells Mol Dis. 2008, 40: 63-67. 10.1016/j.bcmd.2007.07.003.View ArticlePubMedGoogle Scholar
- Wolfl M, Kuball J, Ho WY, Nguyen H, Manley TJ, Bleakley M, Greenberg PD: Activation-induced expression of CD137 permits detection, isolation, and expansion of the full repertoire of CD8+ T cells responding to antigen without requiring knowledge of epitope specificities. Blood. 2007, 110: 201-210. 10.1182/blood-2006-11-056168.PubMed CentralView ArticlePubMedGoogle Scholar
- Han S, Wang B, Cotter MJ, Yang LJ, Zucali J, Moreb JS, Chang L-J: Overcoming immune tolerance against multiple myeloma with lentiviral calnexin-engineered dendritic cells. Mol Ther. 2008, 16: 269-279. 10.1038/sj.mt.6300369.View ArticlePubMedGoogle Scholar
- Fukushima Y, Ohashi H, Wakui K, Nishida T, Oh-ishi T: A rapid method for starting a culture for the establishment of Epstein-Barr virus-transformed human lymphoblastoid cell lines. Jpn J Hum Genet. 1992, 37: 149-150. 10.1007/BF01899737.View ArticlePubMedGoogle Scholar
- Betts MR, Brenchley JM, Price DA, De Rosa SC, Douek DC, Roederer M, Koup RA: Sensitive and viable identification of antigen-specific CD8+ T cells by a flow cytometric assay for degranulation. J Immunol Methods. 2003, 281: 65-78. 10.1016/S0022-1759(03)00265-5.View ArticlePubMedGoogle Scholar
- Lyons AB: Analysing cell division in vivo and in vitro using flow cytometric measurement of CFSE dye dilution. J Immunol Methods. 2000, 243: 147-154. 10.1016/S0022-1759(00)00231-3.View ArticlePubMedGoogle Scholar
- Jedema I, Werff van der NM, Barge RM, Willemze R, Falkenburg JH: New CFSE-based assay to determine susceptibility to lysis by cytotoxic T cells of leukemic precursor cells within a heterogeneous target cell population. Blood. 2004, 103: 2677-2682. 10.1182/blood-2003-06-2070.View ArticlePubMedGoogle Scholar
- Straathof KC, Bollard CM, Popat U, Huls MH, Lopez T, Morriss MC, Gresik MV, Gee AP, Russell HV, Brenner MK, Rooney CM, Heslop HE: Treatment of nasopharyngeal carcinoma with Epstein-Barr virus – specific T lymphocytes. Blood. 2005, 105: 1898-1904. 10.1182/blood-2004-07-2975.View ArticlePubMedGoogle Scholar
- Wehler TC, Karg M, Distler E, Konur A, Nonn M, Meyer RG, Huber C, Hartwig UF, Herr W: Rapid identification and sorting of viable virus-reactive CD4(+) and CD8(+) T cells based on antigen-triggered CD137 expression. J Immunol Methods. 2008, 339: 23-37. 10.1016/j.jim.2008.07.017.View ArticlePubMedGoogle Scholar
- Dauer M, Obermaier B, Herten J, Haerle C, Pohl K, Rothenfusser S, Schnurr M, Endres S, Eigler A: Mature dendritic cells derived from human monocytes within 48 hours: a novel strategy for dendritic cell differentiation from blood precursors. J Immunol. 2003, 170: 4069-4076.View ArticlePubMedGoogle Scholar
- Dummer W, Niethammer AG, Baccala R, Lawson BR, Wagner N, Reisfeld RA, Theofilopoulos AN: T cell homeostatic proliferation elicits effective antitumor autoimmunity. J Clin Invest. 2002, 110: 185-192.PubMed CentralView ArticlePubMedGoogle Scholar
- Klebanoff CA, Khong HT, Antony PA, Palmer DC, Restifo NP: Sinks, suppressors and antigen presenters: how lymphodepletion enhances T cell-mediated tumor immunotherapy. Trends Immunol. 2005, 26: 111-117. 10.1016/j.it.2004.12.003.PubMed CentralView ArticlePubMedGoogle Scholar
- Wrzesinski C, Paulos CM, Gattinoni L, Palmer DC, Kaiser A, Yu Z, Rosenberg SA, Restifo NP: Hematopoietic stem cells promote the expansion and function of adoptively transferred antitumor CD8 T cells. J Clin Invest. 2007, 117: 492-501. 10.1172/JCI30414.PubMed CentralView ArticlePubMedGoogle Scholar
- Watanabe K, Suzuki S, Kamei M, Toji S, Kawase T, Takahashi T, Kuzushima K, Akatsuka Y: CD137-guided isolation and expansion of antigen-specific CD8 cells for potential use in adoptive immunotherapy. Int J Hematol. 2008, 88: 311-320. 10.1007/s12185-008-0134-z.View ArticlePubMedGoogle Scholar
- Alderson MR, Smith CA, Tough TW, Davis-Smith T, Armitage RJ, Falk B, Roux E, Baker E, Sutherland GR, Din WS: Molecular and biological characterization of human 4-1BB and its ligand. Eur J Immunol. 1994, 24: 2219-2227. 10.1002/eji.1830240943.View ArticlePubMedGoogle Scholar
- Wen T, Bukczynski J, Watts TH: 4-1BB ligand-mediated costimulation of human T cells induces CD4 and CD8 T cell expansion, cytokine production, and the development of cytolytic effector function. J Immunol. 2002, 168: 4897-4906.View ArticlePubMedGoogle Scholar
- Zhu Y, Zhu G, Luo L, Flies AS, Chen L: CD137 stimulation delivers an antigen-independent growth signal for T lymphocytes with memory phenotype. Blood. 2007, 109: 4882-4889. 10.1182/blood-2006-10-043463.PubMed CentralView ArticlePubMedGoogle Scholar
- Sun JC, Williams MA, Bevan MJ: CD4+ T cells are required for the maintenance, not programming, of memory CD8+ T cells after acute infection. Nat Immunol. 2004, 5: 927-933. 10.1038/ni1105.PubMed CentralView ArticlePubMedGoogle Scholar
- Sallusto F, Geginat J, Lanzavecchia A: Central memory and effector memory T cell subsets: function, generation, and maintenance. Annu Rev Immunol. 2004, 22: 745-763. 10.1146/annurev.immunol.22.012703.104702.View ArticlePubMedGoogle Scholar
- Nascimbeni M, Shin EC, Chiriboga L, Kleiner DE, Rehermann B: Peripheral CD4(+)CD8(+) T cells are differentiated effector memory cells with antiviral functions. Blood. 2004, 104: 478-486. 10.1182/blood-2003-12-4395.View ArticlePubMedGoogle Scholar
- Gattinoni L, Klebanoff CA, Palmer DC, Wrzesinski C, Kerstann K, Yu Z, Finkelstein SE, Theoret MR, Rosenberg SA, Restifo NP: Acquisition of full effector function in vitro paradoxically impairs the in vivo antitumor efficacy of adoptively transferred CD8+ T cells. J Clin Invest. 2005, 115: 1616-1626. 10.1172/JCI24480.PubMed CentralView ArticlePubMedGoogle Scholar
- Klebanoff CA, Gattinoni L, Torabi-Parizi P, Kerstann K, Cardones AR, Finkelstein SE, Palmer DC, Antony PA, Hwang ST, Rosenberg SA, Waldmann TA, Restifo NP: Central memory self/tumor-reactive CD8+ T cells confer superior antitumor immunity compared with effector memory T cells. Proc Natl Acad Sci USA. 2005, 102: 9571-9576. 10.1073/pnas.0503726102.PubMed CentralView ArticlePubMedGoogle Scholar
- Leen AM, Rooney CM, Foster AE: Improving T cell therapy for cancer. Annu Rev Immunol. 2007, 25: 243-265. 10.1146/annurev.immunol.25.022106.141527.View ArticlePubMedGoogle Scholar
- Masopust D, Vezys V, Marzo AL, Lefrancois L: Preferential localization of effector memory cells in nonlymphoid tissue. Science. 2001, 291: 2413-2417. 10.1126/science.1058867.View ArticlePubMedGoogle Scholar
- Letsch A, Keilholz U, Assfalg G, Mailander V, Thiel E, Scheibenbogen C: Bone marrow contains melanoma-reactive CD8+ effector T cells and, compared with peripheral blood, enriched numbers of melanoma-reactive CD8+ memory T cells. Cancer Res. 2003, 63: 5582-5586.PubMedGoogle Scholar
- Slifka MK, Whitmire JK, Ahmed R: Bone marrow contains virus-specific cytotoxic T lymphocytes. Blood. 1997, 90: 2103-2108.PubMedGoogle Scholar
- Wood AH, Zhang X, Farber DL, Strome SE: CD8+ memory T lymphocytes from bone marrow – immune function and therapeutic potential. Crit Rev Immunol. 2007, 27: 527-537.View ArticlePubMedGoogle Scholar
- Soares MV, Borthwick NJ, Maini MK, Janossy G, Salmon M, Akbar AN: IL-7-dependent extrathymic expansion of CD45RA+ T cells enables preservation of a naive repertoire. J Immunol. 1998, 161: 5909-5917.PubMedGoogle Scholar
- van Stipdonk MJ, Sluijter M, Han WG, Offringa R: Development of CTL memory despite arrested clonal expansion. Eur J Immunol. 2008, 38: 1839-1846. 10.1002/eji.200737974.View ArticlePubMedGoogle Scholar
- Haque T, Wilkie GM, Taylor C, Amlot PL, Murad P, Iley A, Dombagoda D, Britton KM, Swerdlow AJ, Crawford DH: Treatment of Epstein-Barr-virus-positive post-transplantation lymphoproliferative disease with partly HLA-matched allogeneic cytotoxic T cells. Lancet. 2002, 360: 436-442. 10.1016/S0140-6736(02)09672-1.View ArticlePubMedGoogle Scholar
- Lucas KG, Salzman D, Garcia A, Sun Q: Adoptive immunotherapy with allogeneic Epstein-Barr virus (EBV)-specific cytotoxic T-lymphocytes for recurrent, EBV-positive Hodgkin disease. Cancer. 2004, 100: 1892-1901. 10.1002/cncr.20188.View ArticlePubMedGoogle Scholar
- Cobbold M, Khan N, Pourgheysari B, Tauro S, McDonald D, Osman H, Assenmacher M, Billingham L, Steward C, Crawley C, Olavarria E, Goldman J, Chakraverty R, Mahendra P, Craddock C, Moss PA: Adoptive transfer of cytomegalovirus-specific CTL to stem cell transplant patients after selection by HLA-peptide tetramers. J Exp Med. 2005, 202: 379-386. 10.1084/jem.20040613.PubMed CentralView ArticlePubMedGoogle Scholar
- Amrolia PJ, Muccioli-Casadei G, Huls H, Adams S, Durett A, Gee A, Yvon E, Weiss H, Cobbold M, Gaspar HB, Rooney C, Kuehnle L, Ghetie V, Schindler J, Krance R, Heslop HE, Veys P, Vitetta E, Brenner MK: Adoptive immunotherapy with allodepleted donor T-cells improves immune reconstitution after haploidentical stem cell transplantation. Blood. 2006, 108: 1797-1808. 10.1182/blood-2006-02-001909.PubMed CentralView ArticlePubMedGoogle Scholar
- Overwijk WW: Breaking tolerance in cancer immunotherapy: time to ACT. Curr Opin Immunol. 2005, 17: 187-194. 10.1016/j.coi.2005.01.011.View ArticlePubMedGoogle Scholar
- Rabinovich GA, Gabrilovich D, Sotomayor EM: Immunosuppressive strategies that are mediated by tumor cells. Annu Rev Immunol. 2007, 25: 267-296. 10.1146/annurev.immunol.25.022106.141609.PubMed CentralView ArticlePubMedGoogle Scholar
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