Étude des fonctions immunomodulatrices des lymphocytes T « Doubles-Négatifs »

La réaction du greffon contre l’hôte (GvH) est responsable d’un grand taux de morbidité et de mortalité chez les patients recevant des greffes de cellules souches (GCSH) allogéniques. Dans ce contexte, les cellules T régulatrices sont largement étudiées et semblent avoir un grand potentiel d’utilisation dans le domaine de la thérapie cellulaire de la GvH. Parmi les populations cellulaires T régulatrices, les lymphocytes T CD4-CD8- TCRαβ+ « Doubles-Négatifs » (DN), qui ne représentent que 1-3% des lymphocytes T, ont été décrits. Ces cellules ont des propriétés inhibitrices de la réponse immunitaire qui s’avèrent spécifiques aux antigènes auxquels elles ont préalablement été exposées. La répression de la réponse immunitaire par les cellules T DN régulatrices semble être un mécanisme important impliqué dans l’induction de la tolérance aux allo-antigènes. De plus, ces cellules confèrent une tolérance immunitaire dans des modèles de greffes allogéniques et xénogéniques. En effet, ces cellules ont la capacité d’inhiber la réaction contre un allo-antigène auquel elles ont été exposées, sans inhiber la réaction contre un allo-antigène inconnu. Les cellules T DN ont été isolées et caractérisées chez l’homme où elles ont la capacité d’interagir avec des cellules présentatrices d’antigènes (APCs) par un contact cellulaire, comme chez la souris. Cependant, leur capacité immunomodulatrice reste inconnue chez l’humain. Notre objectif consistait donc principalement à étudier le rôle et le mécanisme d’action des cellules T DN régulatrices humaines in vitro, en étudiant leur capacité à inhiber une réaction lymphocytaire mixte (MLR). Nous avons montré que les cellules T DN stimulées par un allo-antigène donné inhibent des cellules syngéniques effectrices dirigées contre ce même alloantigène mais n’inhibent pas des cellules syngéniques effectrices dirigées contre un autre alloantigène, démontrant ainsi la spécificité aux antigènes de ces cellules. De plus, les T DN non stimulées par un allo-antigène n’ont pas de rôle inhibiteur. Cependant, durant cette inhibition, nous n’observons pas de modulation de l’expression des marqueurs d’activation et d’induction de l’apoptose. Afin d’étudier le mécanisme d’action des cellules T DN, nous avons mesuré l’expression intracellulaire de la granzyme B. Les résultats démontrent que les cellules T DN stimulées expriment un niveau significativement plus élevé de granzyme B que les cellules T DN non-stimulées par l’allo-antigène. Ceci suggère que l’immunosuppression induite par les cellules T DN stimulées pourrait passer par la voie granzyme B. Le mécanisme utilisé par ces cellules reste à être confirmé par nos futures expériences.

Utilité et limites du dosage de l'antigène carcinoembryonnaire (CEA) dans la surveillance postopératoire de malades atteints de carcinomes du côlon et du rectu

An attempt is made to define the usefulness and limitations of carcinoembryonic antigen (CEA) radioimmunoassay for evaluation of tumor resection and detection of tumor relapse in patients with large-bowel carcinoma. In 45 patients for whom complete tumor resection was reported, all but 5 showed a drop in CEA to normal values after surgery. The 5 patients whose CEA did not fall to below 5 ng/ml showed a subsequent rise in CEA level and later were all found to have a tumor relapse. The results indicate that an incomplete drop in circulating CEA level one month after surgery is a bad prognostic sign. Twenty-two of these patients were followed up by repeated CEA radioimmunoassay for several months after surgery; 8 showed a progressive increase in CEA levels preceding clinical diagnosis of tumor relapse by 2-10 months. The clinical history of these 8 patients is briefly described. The results demonstrate that relapses of colon and rectum carcinoma can be detected by increased CEA levels months before the appearance of any clinical evidence.

Allogeneic stem cell transplantation after reduced intensity conditioning in patients with relapsed or refractory Hodgkin's lymphoma. Results of the HDR-ALLO study - a prospective clinical trial by the Grupo Español de Linfomas/Trasplante de Médula Osea (GEL/TAMO) and the Lymphoma Working Party of the European Group for Blood and Marrow Transplantation.

BACKGROUND Although Hodgkin's lymphoma is a highly curable disease with modern chemotherapy protocols, some patients are primary refractory or relapse after first-line chemotherapy or even after high-dose therapy and autologous stem cell transplantation. We investigated the potential role of allogeneic stem cell transplantation in this setting. DESIGN AND METHODS In this phase II study 92 patients with relapsed Hodgkin's lymphoma and an HLA-identical sibling, a matched unrelated donor or a one antigen mismatched, unrelated donor were treated with salvage chemotherapy followed by reduced intensity allogeneic transplantation. Fourteen patients showed refractory disease and died from progressive lymphoma with a median overall survival after trial entry of 10 months (range, 6-17). Seventy-eight patients proceeded to allograft (unrelated donors, n=23). Fifty were allografted in complete or partial remission and 28 in stable disease. Fludarabine (150 mg/m(2) iv) and melphalan (140 mg/m(2) iv) were used as the conditioning regimen. Anti-thymocyte globulin was additionally used as graft-versus-host-disease prophylaxis for recipients of grafts from unrelated donors. RESULTS The non-relapse mortality rate was 8% at 100 days and 15% at 1 year. Relapse was the major cause of failure. The progression-free survival rate was 47% at 1 year and 18% at 4 years from trial entry. For the allografted population, the progression-free survival rate was 48% at 1 year and 24% at 4 years. Chronic graft-versus-host disease was associated with a lower incidence of relapse. Patients allografted in complete remission had a significantly better outcome. The overall survival rate was 71% at 1 year and 43% at 4 years. CONCLUSIONS Allogeneic stem cell transplantation can result in long-term progression-free survival in heavily pre-treated patients with Hodgkin's lymphoma. The reduced intensity conditioning approach significantly reduced non-relapse mortality; the high relapse rate represents the major remaining challenge in this setting. The HDR-Allo trial was registered in the European Clinical Trials Database (EUDRACT, https://eudract.ema.europa.eu/) with number 02-0036.

La Traducció de l'humor en "Allo", Allo! : proposta d'una classificació

Aquest treball presenta, a través de l’anàlisi de la traducció de l’humor al català i al castellà de la sèrie britànica ’Allo’Allo!, la classificació que se’n deriva de diferents tipus d’acudits, estratègies i solucions. També valida aquesta classificació com a eina per estudiar l’estil d’un o més doblatges d’un text audiovisual on l’humor és prioritari així com per valorar-ne l’efectivitat. Sobre el corpus inicial d’aquells acudits basats en algun tret lingüístic o cultural no compartit per la llengua o cultura d’arribada, s’ha creat una classificació en quatre nivells que permet una anàlisi quantitativa d’un estil de traducció concret (dins de cada nivell o transversalment) i, a la vegada, la comparació entre dos estils diferents. El primer nivell analitza el tipus d’acudit al text original; el segon, la relació entre aquest i el text meta; el tercer, en quin tipus d’acudit s’ha materialitzat aquesta relació; i, el quart, la seva efectivitat.

Ex vivo characterization of allo-MHC-restricted T cells specific for a single MHC-peptide complex.

Alloreactive T cells are thought to be a potentially rich source of high-avidity T cells with therapeutic potential since tolerance to self-Ags is restricted to self-MHC recognition. Given the particularly high frequency of alloreactive T cells in the peripheral immune system, we used numerous MHC class I multimers to directly visualize and isolate viral and tumor Ag-specific alloreactive CD8 T cells. In fact, all but one specificities screened were undetectable in ex vivo labeling. In this study, we report the occurrence of CD8 T cells specifically labeled with allo-HLA-A*0201/Melan-A/MART-1(26-35) multimers at frequencies that are in the range of 10(-4) CD8 T cells and are thus detectable ex vivo by flow cytometry. We report the thymic generation and shaping of tumor Ag-specific, alloreactive T cells as well as their fate once seeded in the periphery. We show that these cells resemble their counterparts in HLA-A*0201-positive individuals, based on their structural and functional attributes.

Antigène carcino-embryonnaire circulant, fortement élevé et persistant, sans cancer décelable

A markedly elevated circulating CEA level was observed in January 1978 in a 40-year-old male patient who complained of functional digestive disorders consisting of 2-3 bowel movements at the end of each night. During follow-up of more than 3 years the CEA level was always found to be higher than 300 ng/ml as determined on 12 different blood samples using 3 different assays: the Hansen assay, our own inhibition radioimmunoassay performed on perchloric acid extract of serum, and a newly developed solid phase non-competitive enzyme immunoassay involving monoclonal anti-CEA antibody. The clinical evolution showed no aggravation of the persistent but mild bowel troubles, i.e. no real diarrhea or blood in the stool. The patient enjoys excellent general health and shows no weight loss. Barium enema, colonoscopy and extensive investigation by computerized axial tomography showed no evidence of primary or metastatic tumor. Apart from CEA, the blood chemistry was within normal limits. Six members of the patient's family have normal CEA levels. A possible explanation for this unique case of marked and persistent elevation of circulating CEA without evidence of cancer is discussed.

Détermination de l'antigène HLA-G soluble dans le liquide folliculaire et dans le milieu de culture d'embryons comme indicateur du succès d'un traitement par FIV-ICSI [Soluble human leukocyte antigen-G (sHLA-G) in follicular fluid and embryo culture medium and its impact on pregnancy prediction in IVF-ICSI treatment]

In IVF around 70% of embryos fail to implant. Often more than one embryo is transferred in order to enhance the chances of pregnancy, but this is at the price of an increased multiple pregnancy risk. In the aim to increase the success rate with a single embryo, research projects on prognostic factors of embryo viability have been initiated, but no marker has found a routine clinical application to date. Effects of soluble human leukocyte antigen-G (sHLA-G) on both NK cell activity and on Th1/Th2 cytokine balance suggest a role in the embryo implantation process, but the relevance of sHLA-G measurements in embryo culture medium and in follicular fluid (FF) are inconsistent to date. In this study, we have investigated the potential of sHLA-G in predicting the achievement of a pregnancy after IVF-ICSI in a large number of patients (n = 221). sHLA-G was determined in media and in FF by ELISA. In both FF and embryo medium, no significant differences in sHLA-G concentrations were observed between the groups "pregnancy" and "implantation failure", or between the groups "ongoing" versus "miscarried pregnancies". Our results do not favour routine sHLA-G determinations in the FF nor in embryo conditioned media, with the current assay technology available.

Mise au point concernantl'utilisation du dosagede l'antigène carcino-embryonnaire (CEA)en clinique

The carcinoembryonic antigen (CEA) is a tumor marker defined by specific heterologous antisera. Elevated levels of circulating CEA have been detected by radioimmunoassay in 20-90 per cent of cases of colorectal carcinomas depending on the degree of tumor spread. The fact that elevation of CEA level can also be observed in other types of carcinomas and in several non malignant conditions greatly limit the value of the CEA test for the early diagnosis of colorectal carcinoma. Thus, the CEA assay should not be used as a screening test for cancer. Repeatecl CEA mesurements, however, appear to be of importance for the evaluation of tumor resection and the detection of tumor recurrence. The only localized tumors known to produce elevation of CEA above the levels observed in non malignant diseases are carcinomas of the large bowel and the pancreas. In carcinomas derived from other organs a marked increase of CEA level is always associated with the presence of distant metastasis. Therefore at the present time the clinical applications of the CEA radioimmunoassay should be limited to the differentiai diagnosis of patients with suspicion of primary colorectal or pancreatic carcinoma, to the detection of distant metastasis in other types of carcinomas and to the post operative follow up of patients who had elevated levels of CEA before surgery. Well-controlled studies are still needed to determine if therapeutic decisions based on CEA results can lead to improved survival.

Des antisérums dirigés contre l'antigène carcino-embryonnaire (CEA) peuvent induire une lyse spécifique des cellules de carcinome du côlon par des lymphocytes normaux

Antibody-dependent cell-mediated cytotoxicity (ADCC) against human colon carcinoma cells grown in vitro was demonstrated with two specific rabbit anti-carcinoembryonic antigen (cea) antisera. The same antisera did not lyse the colon carcinoma cells in the presence of complement but without lymphocytes. The normal human lymphocytes in the absence of anti-CEA antiserum had a very low cytotoxic activity during the three hours 51Cr release assay used in this study. Two colon carcinoma cell lines, HT-29 and Co-115, expressing CEA on their surface as demonstrated by immunofluorescence, were significantly lysed in the ADCC test, whereas control tumor cell lines, not expressing CEA, were not affected by the anti-CEA sera and the lymphocytes. The specificity of the reaction was further demonstrated by the inhibition of antibody-dependent cell-mediated cytotoxicity after the addition of increasing amounts of purified CEA to the antiserum. The absorption of the anti-CEA antisera was controlled by radioimmunoassay. Absorption of the antisera by normal lung extracts and red cells of different blood groups did not decrease the cytotoxicity.