-
Leukemia research 10/2010; 34(10):e270-2. · 2.36 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Altered expression of major histocompatibility complex (MHC) class I molecules can be caused by defects in genes of the antigen-processing machinery (APM), and is often correlated to progression in solid tumours. However, little is known about expression of the APM components in blasts from patients with acute myeloid leukaemia (AML). In this study, we investigated the expression of the APM components large multifunctional peptidases (LMP) 2 and 7, transporter-associated with antigen processing (TAP) 1 and 2, beta-2-microglobulin (beta2m) and MHC class I heavy chain in situ by tissue microarray from bone marrow biopsies of 30 AML patients. APM components were heterogeneously expressed in all AML samples tested, but no significant correlation with the AML subtype according to the French-American-British classification was found. Depending on the APM component tested, up to 90% of the trephines showed no or weak expression, whereas the LMP7 protein was detected in 66% of all samples. By following disease progression in individual AML patients, we found severe downregulation of APM components in two out of four patients from initial diagnosis to relapse. We conclude that downregulation of APM components may play a role in the failure of immuno-surveillance and may therefore contribute to relapse in acute leukaemia.
Leukemia: official journal of the Leukemia Society of America, Leukemia Research Fund, U.K 02/2009; 23(5):877-85. · 8.30 Impact Factor
-
C M Britten,
C Gouttefangeas,
M J P Welters,
G Pawelec,
S Koch,
C Ottensmeier,
A Mander,
S Walter,
A Paschen,
J Müller-Berghaus, [......],
M Schmitt,
K Giannopoulos,
R Maier,
H Veelken,
C Bertinetti,
A Konur,
C Huber,
S Stevanović,
T Wölfel,
S H van der Burg
[show abstract]
[hide abstract]
ABSTRACT: The interpretation of the results obtained from immunomonitoring of clinical trials is a difficult task due to the variety of methods and protocols available to detect vaccine-specific T-cell responses. This heterogeneity as well as the lack of standards has led to significant scepticism towards published results. In February 2005, a working group was therefore founded under the aegis of the Association for Immunotherapy of Cancer ("CIMT") in order to compare techniques and protocols applied for the enumeration of antigen-specific T-cell responses. Here we present the results from two consecutive phases of an international inter-laboratory testing project referred to as the "CIMT monitoring panel". A total of 13 centers from six European countries participated in the study in which pre-tested PBMC samples, synthetic peptides and PE-conjugated HLA-tetramers were prepared centrally and distributed to participants. All were asked to determine the number of antigen-specific T-cells in each sample using tetramer staining and one functional assay. The results of the first testing round revealed that the total number of cells analyzed was the most important determinant for the sensitive detection of antigen-specific CD8(+) T-cells by tetramer staining. Analysis by ELISPOT was influenced by a combination of cell number and a resting phase after thawing of peripheral blood mononuclear cells. Therefore, the experiments were repeated in a second phase but now the participants were asked to change their protocols according to the new guidelines distilled from the results of the first phase. The recommendations improved the number of antigen-specific T-cell responses that were detected and decreased the variability between the laboratories. We conclude that a two-step approach in inter-laboratory testing allows the identification of distinct variables that influence the sensitivity of different T-cell assays and to formally show that a defined correction to the protocols successfully increases the sensitivity and reduces the inter-center variability. Such "two-step" inter-laboratory projects could define rational bases for accepted international guidelines and thereby lead to the harmonization of the techniques used for immune monitoring.
Cancer Immunology and Immunotherapy 04/2008; 57(3):289-302. · 3.70 Impact Factor
-
N Meidenbauer,
A Zippelius,
MJ Pittet,
M Laumer,
S Vogl,
J Heymann,
M Rehli,
B Seliger,
S Schwarz,
Gal F-A Le,
PY Dietrich,
R Andreesen,
P Romero, A Mackensen
Cancer Cell International. 01/2004;
-
Cancer Cell International. 01/2004;
-
[show abstract]
[hide abstract]
ABSTRACT: The characterization of tumor-associated antigens recognized by human T lymphocytes in a major histocompatibility complex (MHC)-restricted fashion has opened new possibilities for immunotherapeutic approaches to the treatment of human cancers. Dendritic cells (DC) are professional antigen presenting cells that are well suited to activate T cells toward various antigens, such as tumor-associated antigens, due to their potent costimulatory activity. The availability of large numbers of DC, generated either from hematopoietic progenitor cells or monocytes in vitro or isolated from peripheral blood, has profoundly changed pre-clinical research as well as the clinical evaluation of these cells. Accordingly, appropriately pulsed or transfected DC may be used for vaccination in the field of infectious diseases or tumor immunotherapy to induce antigen-specific T cell responses. These observations led to pilot clinical trials of DC vaccination for patients with cancer in order to investigate the feasibility, safety, as well as the immunologic and clinical effects of this approach. Initial clinical studies of human DC vaccines are generating encouraging preliminary results demonstrating induction of tumor-specific immune responses and tumor regression. Nevertheless, much work is still needed to address several variables that are critical for optimizing this approach and to determine the role of DC-based vaccines in tumor immunotherapy.
Biological Chemistry 05/2001; 382(4):507-20. · 2.96 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Melanoma and renal cell carcinoma (RCC) are considered to be the most immunogenic tumors in humans. To generate conditions to induce primary T-cell responses against RCC and to allow further expansion of tumor-specific cytotoxic T lymphocytes (CTL) for adoptive transfer, peripheral blood mononuclear cells from RCC patients were stimulated with primary autologous tumor cells or monocyte-derived dendritic cells (DC) loaded with either tumor lysate (TU-LY) or apoptotic tumor cells (TU-AP). Whereas repetitive stimulation (4x) with tumor cells alone induced a predominant population of CD3(-) natural killer cells, 4 weeks of stimulation with tumor-loaded DC favored induction and expansion of CD4+ T cells (>80%). However, 2 weekly stimulation cycles with tumor-loaded DC followed by restimulation with autologous irradiated tumor cells alone were optimal for induction of tumor-specific CTL responses in vitro. Using these culture conditions a marked increase of CD4+ T cells was observed during the first 2 weeks of stimulation with tumor-loaded DC. Subsequent restimulation with autologous tumor cells alone gave rise to 500-fold expansion of CD8+ T cells. These CD8+ T cells were shown to exhibit strong major histocompatibility complex class I-restricted cytotoxic activity against the autologous tumor. Comparison of TU-LY and TU-AP as a source of tumor antigen for loading DC did not show any difference in stimulating tumor-specific CTL. Length pattern analysis of the complementary determining region 3 (CDR3) of the T-cell receptor Vbeta chain revealed expansion of oligoclonal CTL populations with outgrowth of 1 or 2 clones after prolonged stimulation with autologous tumor cells. Our study demonstrated an efficient method for generating tumor-specific CTL in vitro that may be used to identify tumor cell antigens or that can be expanded for adoptive T-cell transfer in tumor immunotherapy.
International Journal of Cancer 04/2001; 91(6):749-56. · 5.44 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Cell therapy with antigen-specific T cells holds promise for various diseases including cancer and viral infections. The powerful enrichment procedure based on major histocompatibility complex (MHC)-tetramers, however, is of limited applicability so far. Therefore, the recently developed cell surface affinity matrix technology that allows direct identification and enrichment of life antigen-specific T cells based on cytokine secretion was evaluated in this respect. To this end, CD8(+) T cells directed against the HLA-A(*)0201-restricted melanoma-associated peptide Melan-A (aa26-35) were generated by combining stimulation of peptide-pulsed autologous dendritic cells (DC) with antigen-independent expansion with anti-CD3/anti-CD28 monoclonal antibodies (MoAb). Antigen-specific cytotoxic T lymphocyte (CTL) were detected based on stimulation-induced interferon (IFN)-gamma and interleukin (IL)-4 secretion and enriched > 100-fold using the cell surface affinity matrix technology. The resulting IFN-gamma- and IL-4-secreting CTL lines contained > 80% and > 70% cytokine positive T cells, respectively. They exhibited a cytotoxic activity against Melan-A expressing target cells that was significantly higher as compared to nonpurified CTL. Direct staining of enriched CTL with HLA-A2-Melan-A-tetramers revealed a high correlation between the results obtained from the cell surface affinity matrix technology and those obtained from tetrameric complexes. Altogether, our study demonstrates that cytokine-driven enrichment based on the cell surface affinity matrix technology enables selective isolation of functionally active antigen-specific CTL that may be used for an adoptive T cell transfer in immunotherapy.
Scandinavian Journal of Immunology 12/2000; 52(6):544-9. · 2.23 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Dendritic cells are professional antigen-presenting cells that can be generated in vitro either from monocytes or from CD34+ peripheral blood progenitor cells by using recombinant cytokines. These cells have potential implications for immunotherapeutic approaches in the treatment of cancer and other diseases. We have conducted a phase I study in melanoma patients using peptide-pulsed dendritic cells cultured in medium supplemented with 10% fetal calf serum (FCS) and a cocktail of cytokines. Peptide-pulsed dendritic cells were injected intravenously at 2-week intervals. Here we report on a case of type I hypersensitivity anaphylactic reaction after repetitive vaccination with autologous peptide-pulsed cells. Pre-vaccination and post-vaccination serum samples were evaluated for the presence of antibodies to FCS and bovine serum albumin (BSA). A retrospective study in 7 patients vaccinated with FCS-cultured dendritic cells demonstrated the presence of IgG and IgM antibodies to FCS and BSA after vaccination in 6 out of 7 patients. However, IgE antibodies were absent in all patients with the exception of the patient developing anaphylaxis. The patient's serum was demonstrated to contain a strong IgE response directed against BSA. In contrast, 2 patients vaccinated with dendritic cells cultured under serum-free conditions developed no antibodies to FCS and BSA after repetitive vaccination. We suggest that patients can be sensitized with an IgE response against BSA leading to anaphylactic reactions. On the basis of these data, dendritic cells cultured in autologous serum or under serum-free conditions are recommended for therapeutic applications in vivo.
Cancer Immunology and Immunotherapy 07/2000; 49(3):152-6. · 3.70 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Tumor antigens that might serve as potential targets for adoptive T-cell therapy have been defined in different tumor entities, especially in malignant melanoma. To generate conditions to induce primary T-cell responses against different HLA-A*0201-restricted melanoma peptides and to allow further expansion of peptide-specific T cells for adoptive transfer, CD8+-purified T cells from healthy donors were stimulated with Melan-A-pulsed autologous dendritic cells. Dendritic cells were generated in vitro from monocytes with granulocyte macrophage colony-stimulating factor, interleukin-4, and transforming growth factor-beta1. After 3-4 weekly stimulation cycles with Melan-A-pulsed DCs, we were able to induce a strong peptide-specific CTL response in vitro. MHC-peptide tetramer staining revealed a frequency of up to 3.5% CD8+/Melan-A+ T cells. Additional antigen-independent expansion with anti-CD3/anti-CD28 monoclonal antibodies together with interleukin-2 gave rise to 600-fold expansion of CD8+ CTLs that maintained Melan-A specificity and were able to efficiently lyse Melan-A-expressing melanoma cells. To enrich antigen-specific T cells in vitro, we used a recently established technology for analysis and sorting of live cells according to secreted cytokines. In the present study, we demonstrated that Melan-A-specific T cells can be purified by magnetic separation according to secreted IFN-gamma. These cells revealed a very potent monospecific CTL response, even at low E:T ratios, against Melan-A-pulsed and Melan-A-expressing target cells. Altogether, our study demonstrated that we have developed an efficient method for generating large numbers of peptide-specific T cells in vitro that may be used for adoptive T-cell transfer in tumor immunotherapy.
Clinical Cancer Research 06/2000; 6(5):1997-2005. · 7.74 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Dendritic cells (DCs) are professional antigen-presenting cells (APCs) that can be used for vaccination purposes, to induce a specific T-cell response in vivo against melanoma-associated antigens. We have shown that the sequential use of early-acting hematopoietic growth factors, stem cell factor, IL-3 and IL-6, followed by differentiation with IL-4 and granulocyte-macrophage colony-stimulating factor allows the in vitro generation of large numbers of immature DCs from CD34(+) peripheral blood progenitor cells. Maturation to interdigitating DCs could specifically be induced within 24 hr by addition of TNF-alpha. Here, we report on a phase I clinical vaccination trial in melanoma patients using peptide-pulsed DCs. Fourteen HLA-A1(+) or HLA-A2(+) patients received at least 4 i.v. infusions of 5 x 10(6) to 5 x 10(7) DCs pulsed with a pool of peptides including either MAGE-1, MAGE-3 (HLA-A1) or Melan-A, gp100, tyrosinase (HLA-A2), depending on the HLA haplotype. A total of 83 vaccinations were performed. Clinical side effects were mild and consisted of low-grade fever (WHO grade I-II). Clinical and immunological responses consisted of anti-tumor responses in 2 patients, increased melanoma peptide-specific delayed-type hypersensitivity reactions in 4 patients, significant expansion of Melan-A- and gp100-specific cytotoxic T lymphocytes in the peripheral blood lymphocytes of 1 patient after vaccination and development of vitiligo in another HLA-A2(+) patient. Our data indicate that the vaccination of peptide-pulsed DCs is capable of inducing clinical and systemic tumor-specific immune responses without provoking major side effects.
International Journal of Cancer 06/2000; 86(3):385-92. · 5.44 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: An expression system for rapid and standardized production of human recombinant immunoglobulin Fab fragments in E. coli was developed. Functional folding of the Fab fragments was accomplished by the dicistronic expression vector pFab.gammakappa containing specialized leader sequences to direct the immunoglobulin heavy and light chains to the periplasmic bacterial space. A C-terminal hexahistidine tag of the Fd chain facilitated metal affinity chromatography and purification to homogeneity as assessed by SDS PAGE and silver staining. Specific antigen recognition by a hybridoma-derived Fab fragment was indistinguishable from that of the corresponding monoclonal antibody. This protocol may be useful for analysis of the antigen specificity of human B cells and for convenient production of lymphoma-derived idiotype protein for vaccination strategies. To obtain unmodified immunoglobulin cDNA sequences from small human biopsies for insertion into pFab.gammakappa, oligo(dG)-tailed cDNA was amplified with an oligo(dC)- and nested mu or kappa constant region-specific primers. Using single sets of primers for each class of immunoglobulin transcripts, the products of this anchored PCR reflected the relative abundance of the starting cell population and permitted reliable identification of clonal, lymphoma-derived sequences for subsequent expression cloning.
Journal of Immunological Methods 11/1999; 229(1-2):141-53. · 2.20 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Human melanoma cell lines may induce a specific T cell response against tumor cells in vitro. However, after repeated restimulation with autologous tumor cells, expansion of CTL is limited and often apoptosis of the T cells occurs. In order to improve conditions inducing primary T cell responses and thus allowing further expansion of tumor specific T cells for an adoptive transfer, we transfected human melanoma cells with the B7.1 gene (CD80), known to be a potent costimulatory molecule for T cell activation. CD80 expression on melanoma cells resulted in improved primary T cell activation, especially of CD8+ T cells. Furthermore, restimulation with CD80+ tumor cells gave rise to long term proliferating CD8+ T cell lines demonstrating an 100-fold expansion of T cells compared to the 20-30-fold increased numbers obtained with the controls (parental tumor cells +/- anti-CD28). T cells stimulated with CD80+ melanoma cells were found to display a MHC class I-restricted cytotoxic activity against the autologous tumor cells. In conclusion, these studies demonstrate the requirement of costimulation in generating large numbers of tumor specific T cells in vitro that may be used for an adoptive transfer in tumor immunotherapy.
European cytokine network 10/1999; 10(3):329-36. · 1.73 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Success of gene replacement therapy depends on long-term, high level expression of the transgene. Gene therapy vectors incorporating a promoter of a constitutively active eukaryotic gene may allow long-term expression in vivo, but the expression level may be insufficient for therapeutic effects. To enhance transcription from eukaryotic promoters, a strategy with dicistronic vectors encoding the therapeutic gene of interest together with a transcription factor that binds and activates the promoter was tested. Expression vectors for the chimeric tet repressor/VP16 transcription factor (tTA) driven by the human beta-actin promoter were constructed, and tandem tet operators were inserted within the promoter. This arrangement significantly enhanced expression of G-CSF in fibroblasts to higher levels than the immediate/early CMV promoter. Stably transfected fibroblast clones produced up to 2.4 microg G-CSF per 10(6) cells x 24 h. After injection of genetically engineered cells into SCID mice, the enhanced beta-actin promoter construct resulted in marked leukocytosis, whereas the unmodified promoter had only a marginal therapeutic effect. Transcription factor-enhanced, feed-back-activated human promoters may thus achieve higher expression levels than viral control elements, and may be advantageous for gene therapy due to high constitutive activity in vivo.
International Journal of Molecular Medicine 11/1998; 2(4):423-8. · 1.98 Impact Factor
-
FEBS Letters 07/1998; 429(3):426. · 3.54 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Epithelia-associated dendritic cells (DC) including Langerhans cells in the skin (LC) are precursors of lymph node located interdigitating DC (iDC). CD1a+ LC are known to be derived from CD34+ haemopoietic progenitor cells (HPC); however, cells of an intermediate differentiation state that are CD34- and CD1a- have not been identified. Monitoring the differentiation pathway of HPC in the presence of GM-CSF+IL-4, we observed the emergence of a distinct LC precursor population that was CD33+ CD13+ CD4+ CD38+ CD44+ CD34- CD14- CD1a-. The cells could be separated by FACS due to a unique CD44/CD38 expression pattern or by CD44 expression in conjunction with the SSC profile. It was found that they were similarly generated in the presence of GM-CSF alone and were detectable in culture for at least a week. Irrespective of being generated in the presence of GM-CSF+IL-4 or GM-CSF alone, CD44/SSC-sorted precursor cells matured to MHC class II compartments (MIIC) and Birbeck granules (BG) expressing LC, when subsequently cultured in the presence of GM-CSF+IL-4. When IL-4 was omitted, however, the same cells matured to phagocytically active adherent macrophages (Mphi). These culture conditions were associated with a > 4-fold increase in the concentration of IL-6 when compared to those used for LC differentiation. The identification of a distinct oligopotent precursor cell population that can deliberately be induced to give rise to BG+ MIIC+ CD1a+ CD14- LC or to adherent CD14+ Mk further substantiates the close relationship of monocytes and DC and may help to identify its in vivo equivalent.
British Journal of Haematology 06/1998; 101(2):231-41. · 4.94 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: New strategies based on gene transfer technology are employed in cancer therapy. Cytokines are polypeptides involved in immunity and inflammation, and essentially control the magnitude of the immune response. Genetically modified tumor cells releasing various cytokines have been shown to enhance tumor immunogenicity and to induce the regression of preexisting tumors. In some instances, immunological memory has been generated to resist the subsequent challenge with unmodified, parental tumor cells. Cytokine gene transfer into antitumor effector cells, as well as antigen presenting cells, is also being investigated to augment antitumor immune responses.
Stem Cells 02/1998; 16 Suppl 1:251-60. · 7.78 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Dendritic cells (DC) have been generated in vitro from either CD34+ haemopoietic progenitor cells (HPC) or peripheral blood monocytes (Mo) in the presence of specific cytokine combinations, including granulocyte-macrophage colony-stimulating factor (GM-CSF). Since differences between DC from either source may be important for the clinical use of these antigen-presenting cells (APC), a comparative analysis was performed. HPC were expanded in the presence of interleukin (IL)-3, IL-6 and stem cell factor (SCF) (days 1-7) and subsequently induced by IL-4+ GM-CSF (days 8-26) to differentiate to Langerhans-type cells (pLC). The latter cytokines were similarly used to generate Mo-derived LC (mLC). Maturation of both cell types, pLC and mLC, to interdigitating DC-type cells (iDC) was induced by tumour necrosis factor-alpha (TNF-alpha) or lipopolysaccharide (LPS). Analysis of mLC/pLC and miDC/piDC with respect to morphology, phenotype, antigen uptake and presentation revealed a high similarity of DC from either source. The majority of mLC, however, exhibited a more mature differentiation stage, compared to pLC, evidenced from lower numbers of multilaminar MHC class II compartments and less efficient APC function for extracellular protein antigens. Although macropinocytosis was performed by LC, neither LC nor iDC from either source were able to take up > or = 0.5 microm latex beads. However, phagocytosis of 0.5 microm and 1 microm beads was performed by Mo that could subsequently be induced to become iDC, thus providing the unique opportunity to present phagocytosed material in DC-type fashion. Mo may be the preferential source for clinical use of iDC-type cells since preparation and culture are easier to perform and are less costly while APC function is similar to HPC-derived iDC.
British Journal of Haematology 12/1997; 99(3):490-9. · 4.94 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The use of immunostimulatory cytokines has become an increasingly promising approach in cancer immunotherapy. The major goal is the activation of tumour-specific T lymphocytes capable of rejecting tumour cells from patients with low tumour burden or to protect patients from a recurrence of the disease. Strategies that provide high levels of immunostimulatory cytokines locally at the site of antigen have demonstrated pre-clinical and occasional clinical efficacy. Animal models using poorly immunogenic tumours revealed that tumour cells genetically engineered to produce cytokines like IL-2, IL-4, IL-7, IL-12, IFNs, GM-CSF or TNF-alpha were found to be effective in eradicating disseminated tumours. Experimental data obtained from these different animal models are reviewed here to provide an overview of this rapidly evolving field. The data obtained so far from clinical trials involving cytokine gene-modified cells have provided important information regarding the feasibility, safety, immunological effects and occasional clinical responses.
Cytokine & Growth Factor Reviews 07/1997; 8(2):119-28. · 7.81 Impact Factor
-
A Mackensen,
H Veelken,
M Lahn,
S Wittnebel,
D Becker,
G Köhler,
P Kulmburg,
U Brennscheidt,
F Rosenthal,
B Franke,
R Mertelsmann,
A Lindemann
[show abstract]
[hide abstract]
ABSTRACT: In a phase I trial designed to study a vaccine composed of autologous tumor cells and interleukin-2 gene transfected fibroblasts we analyzed lymphocytes infiltrating the vaccination site (VIL) in two melanoma patients. Functional studies demonstrated that numbers of MHC class I restricted cytotoxic T cells directed against the autologous tumor had increased at the immunization site in both cases. Analysis of the variability of T cell receptors (TCR) in the VIL of one patient revealed that the cytotoxic T lymphocytes consisted of a predominant population of TCRBV21S3+ T cells. Enrichment of this subpopulation to more than 99% by specific anti-TCRBV21S3 monoclonal antibody linked immunomagnetic beads and sequencing of the TCR-beta chain disclosed exactly the same V-D-J junctional sequence in all eight TCRBV21 transcripts from these VIL. The identical sequence was also detected in all eight TCRBV21 transcripts from the patient's tumor-infiltrating lymphocytes, indicating that the same CTL clone had infiltrated the tumor, circulated in the peripheral blood, and was amplified at the vaccination site. The TCRBV21S3+ T cells were also found to display an MHC class I restricted cytotoxic activity specifically directed against the autologous tumor cells. At the beginning of treatment these cells were undetectable at the vaccination site and delayed-type hypersensitivity testing was negative, contrasting with the positive results after therapy. Thus it is likely that vaccination with autologous tumor cells plus interleukin-2 gene transfected allogeneic fibroblasts had induced not only local accumulation but also an increase in the frequency of circulating tumor specific CTL.
Journal of Molecular Medicine 05/1997; 75(4):290-6. · 4.67 Impact Factor
