Substantial reduction of human Salmonella Enteritidis infections in Luxembourg in 2005.
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Disease Outbreaks↗
Biomedical subjects
J Even
Publications and source records attributed to J Even.
The infection of human dendritic cells with recombinant avipox vectors expressing a costimulatory molecule transgene (CD80) to enhance the activation of antigen-specific cytolytic T cells.
Human dendritic cells (DCs) express MHC class I and II molecules and several T-cell costimulatory molecules that contribute to their efficiency as antigen-presenting cells (APCs). Whereas most human DC populations uniformly express some costimulatory molecules such as B7-2 (CD86), previous studies have shown a wide variation in the expression of B7-1 (CD80) among different human DC preparations. In the studies reported here, we demonstrate that replication-defective avipox vectors expressing B7-1 can be used to rapidly and efficiently infect human DCs and can enhance the efficacy of human DCs to activate specific human T-cell populations. This has been demonstrated both in systems using peptide as a source of signal 1 and in systems using recombinant avipox vector to deliver signal 1. The antigen used in these studies was the tumor-associated human carcinoembryonic antigen (CEA). An immunodominant 9-mer CTL epitope for CEA (designated CAP-1) has been previously characterized (K. Y. Tsang et al., J. Natl. Cancer Inst. (Bethesda), 87: 982-990, 1995). The source of signal 1 used in these studies was (a) the CAP-1 peptide; (b) recombinant avipox-CEA; or (c) the dual transgene recombinant avipox-CEA/B7-1. These studies demonstrate that CEA-specific T cells are more efficiently activated using as APCs peptide-pulsed DCs infected with avipox-B7-1, as compared with peptide-pulsed DCs infected with wild-type vector, or with uninfected peptide-pulsed DCs. Greater activation of CEA-specific T cells was also obtained using as APCs DCs that were infected with avipox-CEA/B7-1 as compared with the use of DCs infected with avipox-CEA. A CEA tetramer was also used to isolate high- and low-tetramer-binding CEA-specific T-cell populations. Although both high- and low-tetramer-binding T cells had the ability to lyse CEA peptide-pulsed targets, only the high-tetramer-binding T cells had the ability to lyse colon carcinoma cells expressing CEA, which suggests the existence of tetramer-binding populations with different T-cell receptor (TCR) affinities. The demonstrated safety of recombinant avipox vectors in humans and the previously demonstrated ability to administer them multiple times without host immune response limitations indicate that these vectors expressing B7-1 have a potential use in enhancing the efficacy of human DC immunotherapy protocols using either peptide or recombinant vector to deliver signal 1.
Antigen Presentation↗
Generation of helper and cytotoxic CD4+T cell clones specific for the minor histocompatibility antigen H-Y, after in vitro priming of human T cells by HLA-identical monocyte-derived dendritic cells.
BACKGROUND: There is now convincing evidence that minor histocompatibility antigens (mHag) may play a significant role in the pathogenesis of graft-versus-host disease after HLA-identical bone marrow transplantation. Indeed, in this clinical situation, T cells specific for mHag have been isolated. Here, we addressed whether one can generate mHag-specific T cells in vitro, without any in vivo immunization, among healthy blood donors. METHODS: We used monocyte-derived dendritic cells (Mo-DCs) as antigen presenting cells to induce primary responses between healthy HLA-identical siblings, in mixed lymphocyte dendritic cell reactions (MLDCRs). RESULTS: We show that CD4+ T-cell clones, specific for the mHag H-Y, can be generated in vitro. These clones were derived from a gender-mismatched positive MLDCR pair of HLA-identical siblings and were restricted by the HLA DQB1*0502 molecule. In addition, these CD4+ T clones were also able to lyse allogeneic targets with the same pattern of restriction and specificity than helper function. Finally, acute myeloid leukemia (AML) blast cells were susceptible to lysis by these clones. CONCLUSIONS: Altogether, these results predict that Mo-DCs could help to generate class II-associated, mHag-specific, T-cell lines or clones in vitro, between healthy blood donors, without any need of transplantation-mediated immunization.
Acute Disease↗
Severe and long-lasting disruption of T-cell receptor diversity in human myeloma after high-dose chemotherapy and autologous peripheral blood progenitor cell infusion.
Vaccine-based strategies are currently under investigation as a means of inducing tumour-specific immune responses and improving the clinical outcome of multiple myeloma (MM) patients in remission after high-dose chemotherapy and peripheral blood progenitor cell (PBPC) infusion. The immune competence of these patients was investigated by determining the overall diversity of the T-cell receptor (TCR) repertoire in the peripheral blood (PB) and bone marrow (BM). The average time after transplantation was 13 months. The clonality and reciprocal usage of BV gene segments (TCRBV repertoire) was estimated at the cDNA level and membrane protein expression. The TCRBV repertoire of MM was severely disrupted compared with age-matched normal donors. On average, one-third of the total repertoire in both the PB and the BM consisted of T cells expressing oligoclonal TCRbeta transcripts. Flow cytometry showed an increased frequency of abnormally expanded BV subfamilies at both sites. BV expansions were predominantly CD8+ and had the phenotype of antigen-experienced memory T cells as well as T cells with the naive phenotype. Oligoclonality was not restricted to phenotypically expanded BV subfamilies, but also involved normally represented BV subfamilies. The TCR repertoire of MM in remission was then compared with monoclonal gammopathy of undetermined significance (MGUS) and MM patients at diagnosis. The degree of TCR diversity was similar in age-matched normal donors and MGUS, but progressively decreased from MGUS to MM at diagnosis and then to MM in remission. These data indicate that: (1) there is a long-lasting and severe disruption of TCR diversity after high-dose chemotherapy and PBPC infusion, and (2) the extent of TCR disruption may affect the clinical outcome of vaccine-based strategies delivered at the stage of minimal residual disease.
Bone Marrow Cells↗
Diversity of human alpha beta T cell receptors.
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Binding Sites↗
CD95 ligand expression as a mechanism of immune escape in breast cancer.
Interaction of CD95 (Apo-1/Fas) and its ligand (CD95L) plays an important role in the regulation of the immune response, since CD95+ lymphocytes may be killed after engagement of the CD95 receptor. Studying the CD95/CD95L system in 40 cases of breast cancer, the malignant cells expressed CD95L, but lost CD95 expression, when compared with non-malignant mammary tissue. Jurkat T cells incubated on breast cancer sections underwent CD95L-specific apoptosis. The rate of apoptosis correlated with the CD95L mRNA levels of the tissue samples. In four breast cancer cell lines, CD95L expression was increased by interferon-gamma (IFN-gamma), which resulted in higher levels of CD95L-specific apoptosis in co-cultured Jurkat T cells. Since IFN-gamma is mainly secreted by activated T cells, up-regulation of CD95L in breast cancer cells in response to IFN-gamma may thus counterselect activated tumour-infiltrating T cells and favour the immune escape of breast cancer. As demonstrated by inhibition of matrix metalloproteinases, CD95L expressed on breast cancer cells can also be shed from the cell membrane into the culture supernatant. Supernatants derived from cultured breast cancer cells induced apoptosis in Jurkat T cells via CD95L. In breast cancer patients, depletion of CD4+ and CD8+ peripheral blood lymphocytes was significantly correlated with CD95L expression in the tumours. This might be suggestive for a relationship between CD95L expression by breast cancer and systemic immunosuppression.
Apoptosis↗
A direct estimate of the human alphabeta T cell receptor diversity.
Generation and maintenance of an effective repertoire of T cell antigen receptors are essential to the immune system, yet the number of distinct T cell receptors (TCRs) expressed by the estimated 10(12) T cells in the human body is not known. In this study, TCR gene amplification and sequencing showed that there are about 10(6) different beta chains in the blood, each pairing, on the average, with at least 25 different alpha chains. In the memory subset, the diversity decreased to 1 x 10(5) to 2 x 10(5) different beta chains, each pairing with only a single alpha chain. Thus, the naïve repertoire is highly diverse, whereas the memory compartment, here one-third of the T cell population, contributes less than 1 percent of the total diversity.
Adult↗
Idiotype vaccination in human myeloma: generation of tumor-specific immune responses after high-dose chemotherapy.
Igs contain unique portions, collectively termed idiotypes (Id), that can be recognized by the immune system. Id expressed by tumor cells in B-cell malignancies can be regarded as tumor-specific antigens and a target for vaccine immunotherapy. We have started a vaccination trial in multiple myeloma (MM) using Id-specific proteins conjugated to keyhole limpet hemocyanin (KLH) as immunogens and low doses of subcutaneous granulocyte-macrophage colony-stimulating factor (GM-CSF) or interleukin-2 (IL-2) as immunoadjuvants. Twelve patients who had previously been treated with high-dose chemotherapy followed by peripheral blood progenitor cell (PBPC) transplantation entered this study from August 1995 to January 1998. All patients were in first remission at the time of vaccination. They received subcutaneous injections of Id vaccines and immunoadjuvants in an outpatient setting. The generation of Id-specific T-cell proliferative responses was documented in 2 patients, whereas a positive Id-specific delayed-type hypersensitivity (DTH) reaction was observed in 8 of the 10 patients studied. DTH specificity was confirmed in 1 patient by investigating the reactivity to synthetic peptides derived from the VDJ sequence of the tumor-specific Ig heavy chain. None of the patients generated soluble immune responses to Id, whereas the generation of soluble and cellular immune responses to KLH was observed in 100% and 80%, respectively. Eleven patients completed the treatment, whereas 1 patient failed to finish owing to progression of disease. Freedom from disease progression (FFDP), measured from the date of first Id/KLH injection to the date of first treatment after vaccination or last follow-up, ranged from 9 to 36 months. These data indicate that the immune competence status of MM patients is still susceptible to specific immunization after high-dose chemotherapy and PBPC transplantation. It remains to be determined whether generation of Id-specific immune responses can reduce the relapse rate of patients with minimal residual disease.
Adjuvants, Immunologic↗
Regulation of CD95 (Apo-1/Fas) ligand and receptor expression in squamous-cell carcinoma by interferon-gamma and cisplatin.
CD95 (Apo-1/Fas) ligand (CD95L) expression has been observed in various malignancies. In human primary cell lines from a squamous cell carcinoma (SCC) of the vulva, the effect of cisplatin (CDDP) and IFNgamma on the expression of CD95L and its 2 receptor isoforms, CD95 transmembrane (CD95tm) and CD95 soluble receptor, was studied at the mRNA and protein levels. Addition of CDDP and IFNgamma increased CD95L mRNA levels in the primary cell line 6-fold and 1.7-fold, respectively. In comparison, CD95tm mRNA levels were diminished by CDDP but increased 8-fold upon IFNgamma challenge. CD95L expressed by SCC cells was functionally relevant since these cells were able to induce CD95-specific apoptosis in autologous lymphocytes from the SCC-bearing patient. Thus, CD95L expression in SCC may contribute to tumor-associated immunosuppression, which may be modulated by CDDP and IFNgamma. In tumor samples of the primary SCC, CD95L expression was enhanced in the area of the border between invasive tumor tissue and surrounding stroma cells. The locally restricted over-expression of CD95L was congruent with the arrangement of apoptotic stroma cells in the direct vicinity of invading tumor tongues, suggesting a role as invasion factor for CD95L.
Antineoplastic Agents↗
CD95 ligand expression in dedifferentiated breast cancer.
CD95 ligand expression has been observed in various malignancies. Studying the CD95 ligand (CD95L) and receptor (CD95) system in eight non-malignant mammary tissues and 40 breast cancer tissues, mRNA and protein expression was determined by quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) and immunofluorescence. mRNA levels of CD95L correlated positively (r=0.90; p< 0.01) and transmembrane CD95 inversely (r=-0.88; p< 0.01) with histopathological grading of the breast tumours: CD95L mRNA levels were low in adenomas, but increased by 20-fold in grade I, 120-fold in grade II, and 310-fold in grade III breast cancer. In contrast, CD95 mRNA levels were low in high-grade carcinomas, but high in benign mammary tissues. Since CD95L acts as an efficient inducer of apoptosis in CD95(+) cells, apoptotic cells were identified on the tissue sections. Tumour-infiltrating lymphocytes and stromal cells in close proximity to CD95L-expressing breast cancer underwent apoptosis. As a functional test, CD95(+) target cells were cultured on breast cancer tissue sections. The target cells underwent apoptosis when cultured on breast cancer sections, but could be rescued when CD95L was specifically blocked by a CD95-Fc fusion molecule. The data suggest an inverse regulation of CD95 ligand and receptor expression during dedifferentiation of breast cancer. Killing of bystander cells by the CD95L-expressing breast tumour could be involved in tissue invasion.
Adult↗
Involvement of soluble CD95 in Churg-Strauss syndrome.
Deficiency of CD95 (Apo-1/Fas)-mediated apoptosis has recently been found in some autoimmune lymphoproliferative disorders due to inherited mutations of the CD95 gene. In this study, impairment of CD95 ligand-mediated killing of lymphocytes and eosinophils in Churg-Strauss Syndrome (CSS), which was a result of variation of CD95 receptor isoform expression, is demonstrated. Compared to those from healthy individuals, peripheral blood lymphocytes from eight CSS patients exhibit a switch from the membrane-bound CD95 receptor expression to its soluble splice variant, which protects from CD95L-mediated apoptosis. In five out of seven CSS patients recurrent oligoclonal T cell expansions were found, all using a Vbeta-gene from the Vbeta21 family associated with similar CDR3 motifs, indicating the predominance of T cell clones of a similar specificity in the CSS patients. In two of them, the effect of immunosuppressive therapy was studied. In both cases aberrant overexpression of the soluble CD95 receptor isoform and deviations from normal TCR Vbeta-gene usage normalized in parallel with the clinical improvement. Furthermore, soluble CD95 was identified as a survival factor for eosinophils rescuing eosinophils from apoptosis in the absence of growth factors in vitro. Given the role of eosinophils as effector cells in CSS, these findings suggest that soluble CD95 may be mechanistically involved in the disease.
Adult↗
T-cell repertoire analysis in chronic plaque psoriasis suggests an antigen-specific immune response.
Psoriasis is a chronic inflammatory cutaneous disease of unknown etiology. Activation of T cells is thought to play a major role in the pathophysiology of psoriasis. In order to gain insight into the nature of the antigen (superantigen or nominal protein antigen) involved in psoriatic lesions, we have used a RT-PCR method to analyze the frequency of the 24 T cell receptor V beta chain (TCRBV) subfamilies and the size of the antigen-binding region (CDR3), using the immunoscope assay, in skin lesions of patients with chronic plaque-type psoriasis. Semi-quantitative analysis showed that no significant difference in V beta subfamily usage could be detected in T lymphocytes infiltrating lesional skin as compared to blood lymphocytes. Alternatively, determination of the size distribution of the CDR3 of all the V beta subfamilies revealed only in psoriatic skin a marked TCR oligoclonality defined by the presence in 3 to 5 V beta subfamilies of a single predominant CDR3 size which was associated with a unique V beta-J beta combination. Identical patterns of CDR3 length and V beta-J beta combination profiles were found in symetrical lesional sites from two psoriatic patients. This type of skewed CDR3 size profile is reminiscent of a local stimulation of T lymphocytes by nominal protein antigens. These data suggest that T lymphocytes infiltrating plaque-type psoriatic skin comprise expansions of oligoclonal T cells in response to stimulation by an antigen present in the skin.
Adult↗
Case Report: Acute graft-versus-host disease after bone marrow transplantation with a single HLA-DPB1*1001 mismatch: involvement of different TCRBV subsets.
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Journal Article↗
The umbilical cord blood alphabeta T-cell repertoire: characteristics of a polyclonal and naive but completely formed repertoire.
Umbilical cord blood (CB) constitutes a promising alternative to bone marrow for allogeneic transplantation and is increasingly used because of the reduced severity of graft-versus-host disease after CB transplantation. We have compared the T-cell receptor beta chain (TCRB) diversity of CB lymphocytes with that of adult lymphocytes by analyzing the complementarity determining region 3 (CDR3) size heterogeneity. In marked contrast to adult samples, we observed bell-shaped profiles in all of the 22 functional beta-chain variable (BV) subfamilies that reflect the lack of prior antigenic stimulation in CB samples. However, the mean CDR3 size and BV usage were comparable between CB and adult samples. BJ2 (65%) segments were used preferentially to BJ1 (35%), especially BJ2S7, BJ2S5, BJ2S3, and BJ2S1, in both CB and in adult lymphocytes. We therefore conclude that although naive as reflected by the heterogeneity of the CDR3 size, the TCRBV repertoire appears fully constituted at birth. The ability to expand TCRB subfamilies was confirmed by stimulation with staphylococcal superantigens toxic shock syndrome toxin-1 and staphylococcal enterotoxin A. This study provides the basis for future analysis of the T-cell repertoire reconstitution following umbilical CB transplantation.
Adult↗
Deranged CD95 system in a case of Churg-Strauss vasculitis.
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CD4-Positive T-Lymphocytes↗
Acute graft-versus-host disease after bone marrow transplantation with a single HLA-DPB1*1001 mismatch: involvement of different TCRBV subsets.
HLA-DP incompatibility is not considered as an exclusion criterion for bone marrow donors, because such incompatibility was not shown to affect significantly the risk for acute graft-versus-host disease (GVHD). In line with this clinical observation, it was proposed that in the context of bone marrow transplantation, HLA-DP determinants did not function as transplantation antigens in the same way as HLA-A, -B or -DR. In contrast to the above conclusion, we recently demonstrated the presence of HLA-DPB1*0501 specific T cell clones in a skin biopsy of a patient who developed aGVHD after receiving a bone marrow transplant (BMT) in which the only mismatched allele in the GVHD direction was HLA-DPB1*0501. At that time, this case was unique and occurred in a relatively uncommon graft setting where the patient received purified CD34+ BM cells from an unrelated donor. In the present study, we analyzed the immunological events associated with an aGVHD which occurred in the context of a 'regular' allogeneic BMT involving a single HLA-DPB1*1001 mismatch between donor and recipient in the GVHD direction. To this end, we analyzed several amplified T cell subsets present within a T cell line derived from a skin biopsy performed at the onset of GVHD. Our results demonstrated that T cell populations belonging to the TCRBV2, TCRB6.7, TCRBV14 and TCRBV17 subsets were specific for the HLA-DPB1*1001 mismatched allele. These data strengthen and generalize our first conclusion that a single HLA-DP mismatch between donor and recipient can activate a strong T cell response in vivo and consequently challenge the notion that HLA-DP incompatibility should not be taken into account in the choice of BM donors. Moreover, they also underline the idea that HLA-DP antigens may represent an interesting immune target for future therapeutic approaches.
Adult↗
Tumor-specific immune response: current in vitro analyses may not reflect the in vivo immune status.
Although our knowledge and understanding of tumor-specific cytotoxic T lymphocytes (CTL) have expanded considerably, the long-term work needed to assay CTL has precluded their analysis in large numbers of patients. Moreover, in vitro culture steps may introduce major biases. New approaches to identify tumor-specific CTL clones would be helpful. As a means to describe the in situ immune status by T-cell repertoire analysis, we developed the Immunoscope approach, a PCR-based method that allows us to determine the spectra of CDR3 lengths of the TCR chains displayed by complex populations of T cells. We review here some of our data about melanoma. Tumor-infiltrating lymphocytes of a melanoma patient were analyzed by different means and melanoma-specific T-cell clones were derived. Two categories of tumor-specific CD8+ CTL clones were derived from the infiltrate of a tumor-proximal invaded lymph node. The majority of T-cell clones specifically lyse the autologous tumor cell lines and predominantly recognize the HLA-A2/MART-1(27-35) peptide complex. The in vivo representativity of such CTL was assessed by the immunoscope technology. Among three MART-1-specific clones, none was detectable in situ. The other kind of tumor-specific CD8+ CTL did not lyse autologous melanoma cell lines but lysed the "fresh" autologous tumor cells in a MHC class I dependent manner. The immunoscope approach revealed that one of the latter was detectable in situ among tumor-infiltrating lymphocytes although not among PBMC. These data indicate that melanoma-specific lymphocytes that could not have been selected through conventional screening procedures may be important in tumor rejection. Our results suggest that a better characterization of tumor-specific immune responses will be important for the optimization of specific immunotherapy strategies and the long-term follow-up of patients.
Animals↗
Expanded CD4+ and CD8+ T cell clones in elderly humans.
The diversity of the human TCR repertoire in aging has been studied by examining the profiles of complementarity-determining region 3 (CDR3) sizes expressed by the BV families. The TCRBV CDR3 profile, which shows size heterogeneity in young adult humans, is significantly restricted in aged humans. Clonal T cell expansions were identified using a PCR-based approach, in one or more BV families from all 14 healthy persons over the age of 65 that we studied. CD4+ T cell expansions were identified in 8 of 11 donors and CD8+ T cell expansions in 7 of 10 donors. These clonal expansions were stable during a 2-year period. Interestingly, more than half of the aged persons had clonal expansions within the BV3, -14, -16, and -23 families. Although there was no homology among the eight CDR3 sequences identified in clonal T cells from 8 aged persons, selective pressure on the expanded T cell clones was suggested by the fact that the BV families used by the T cell clones were not proportional to the number of genes in the different BV families.
Adult↗