Jacqueline D. Trudeau

Prediction of spontaneous autoimmune diabetes in NOD mice by quantification of autoreactive T cells in peripheral blood

Autoimmune (type 1) diabetes mellitus results from the destruction of insulin-producing pancreatic beta cells by T lymphocytes. Prediction of cell-mediated autoimmune diseases by direct detection of autoreactive T cells in peripheral blood has proved elusive, in part because of their low frequency and reduced avidity for peptide MHC ligands. This article was published online in advance of the print edition. The date of publication is available from the JCI website, http://www.jci.org.

In Situ β Cell Death Promotes Priming of Diabetogenic CD8 T Lymphocytes

CTLs are important mediators of pancreatic β cell destruction in the nonobese diabetic mouse model of type 1 diabetes. Cross-presentation of Ag is one means of priming CTLs. The death of Ag-bearing cells has been implicated in facilitating this mode of priming. The role of β cell death in facilitating the onset of spontaneous autoimmune diabetes is unknown. Here, we used an adoptive transfer system to determine the time course of islet-derived Ag presentation to naive β cell-specific CD8 T cells in nonobese diabetic mice and to test the hypothesis that β cell death enhances the presentation of β cell autoantigen. We have determined that β cell death enhances autoantigen presentation. Priming of diabetogenic CD8 T cells in the pancreatic lymph nodes was negligible before 4 wk, progressively increased until 8 wk of age, and was not influenced by gender. Administration of multiple low doses of the β cell toxin streptozotocin augmented in situ β cell apoptosis and accelerated the onset and magnitude of autoantigen presentation to naive CD8 T cells. Increasing doses of streptozotocin resulted in both increased pancreatic β cell death and significantly enhanced T cell priming. These results indicate that in situ β cell death facilitates autoantigen-specific CD8 T cell priming and can contribute to both the initiation and the ongoing amplification of an autoimmune response.

Regulation of Autoimmune Diabetes by Complete Freund’s Adjuvant Is Mediated by NK Cells

Autoimmune (type 1) diabetes results from a loss of β cells that is mediated by self-reactive T cells. Previous studies have shown that a single injection of CFA prevents diabetes in nonobese diabetic (NOD) mice, but the mechanism(s) of protection remain unknown. We show here that NOD mice immunized with CFA have a markedly reduced incidence of diabetes and that this reduced incidence is associated with a decrease in the number of β cell-specific, autoreactive CTL. In addition, the adoptive transfer of diabetes into syngeneic NOD/SCID recipients was prevented by CFA immunization, and the protective effects of CFA were lost when cells expressing the NK cell marker, asialo GM1, were removed from both donor cells and recipient mice. Returning a population of CD3−DX5+ cells to the adoptive transfer restored the protective effects of CFA. Therefore, NK cells mediate the protective effects of CFA possibly through the down-regulation of autoreactive CTL and stimulation of NK cells represents a novel approach to the prevention of autoimmune diabetes.

Expansion of the Antigenic Repertoire of a Single T Cell Receptor upon T Cell Activation

Activated T cells and their naive precursors display different functional avidities for peptide/MHC, but are thought to have identical antigenic repertoires. We show that, following activation with a cognate mimotope (NRP), diabetogenic CD8+ T cells expressing a single TCR (8.3) respond vigorously to numerous peptide analogs of NRP that were unable to elicit any responses from naive 8.3-CD8+ T cells, even at high concentrations. The NRP-reactive, in vivo activated CD8+ cells arising in pancreatic islets of nonobese diabetic mice are similarly promiscuous for peptide/MHC, and paradoxically this promiscuity expands as the aviditiy of the T cell population for NRP/MHC increases with age. Thus, activation and avidity maturation of T lymphocyte populations can lead to dramatic expansions in the range of peptides that elicit functional T cell responses.

Optimization of epicutaneous immunization for the induction of CTL

The immune system of the skin has recently been exploited for the development of non-invasive vaccine technologies. However, one of the limitations of current vaccine protocols is the inefficient priming of cytotoxic T lymphocytes (CTL). In this study, we report that the application of either an immunodominant class I MHC restricted ovalbumin peptide or whole ovalbumin protein, to tape-stripped skin together with the co-application of the bacterial enterotoxin cholera toxin (CT) induces antigen-specific CTL. Tape-stripping (TS) was found to enhance the magnitude of antibody responses to co-administered protein and to promote the generation of antigen-specific IgG(2a) responses. As well, both cholera toxin and tape-stripping enhanced epidermal dendritic cell (DC) immigration into draining lymph nodes. The adjuvant effect of co-administered cholera toxin and tape-stripping in promoting CTL priming was not dependent on IL-12. Epicutaneous immunization has previously been shown to induce robust antibody responses to administered protein antigen. We now demonstrate the induction of robust and persistent CTL responses to epicutaneously administered protein antigen. Epicutaneous immunization is cheap, simple and effective. These findings suggest the potential use of the skin for the generation of protective immune responses to both viral and tumor challenge.

Should intraoperative cell-salvaged blood be used in patients with suspected or known malignancy?

PurposeIntraoperative cell salvage (ICS) is used as an alternative to allogeneic blood transfusion in an attempt to avoid or minimize the risks associated with allogeneic blood. Intraoperative cell salvage is generally avoided in surgeries where malignancy is confirmed or suspected due to concern for potential metastasis or cancer recurrence. The application of post-processing methods for ICS is hypothesized to eliminate this potential risk. The purpose of this narrative review is to examine the in vitro experimental evidence as it pertains to the removal of tumour cells from ICS blood and to review the clinical studies where ICS blood has been used in patients with malignancy.SourceA search of the English literature for relevant articles published from 1973 to 2012 was undertaken using MEDLINE and Cochrane databases. Bibliographies were cross-referenced to locate further studies.Principal findingsLeukoreduction filters are an effective method for removal of malignant cells from ICS blood. Small non-randomized clinical studies to date do not show evidence of an increased rate of metastasis or cancer recurrence. Although a theoretical risk of disease recurrence persists, the decision to use autologous ICS blood must be weighed against the known risks of allogeneic blood transfusion.ConclusionTransfusion of autologous blood harvested via ICS should be considered a viable option for reduction or avoidance of allogeneic product during many oncologic surgeries and may be a lifesaving option for those patients who refuse allogeneic blood products.RésuméObjectifL’épargne peropératoire de cellules sanguines (ICS) est utilisée comme méthode de remplacement des transfusions de sang allogène pour éviter ou minimiser les risques qui lui sont associés. L’épargne peropératoire des cellules sanguines est généralement évitée au cours des interventions chirurgicales lorsqu’un processus malin est confirmé ou suspecté en raison de la crainte de métastases potentielles ou de récidive du cancer. L’hypothèse d’une utilisation des méthodes de traitement post-ICS est formulée pour éliminer ce risque. Cet article a pour objectif d’analyser les données probantes expérimentales in vitro concernant la suppression de cellules tumorales de sang d’ICS et de passer en revue les études cliniques au cours desquelles du sang d’ICS a été utilisé chez des patients souffrant de processus malins.SourceUne recherche d’articles pertinents publiés entre 1973 et 2012 a été effectuée dans la documentation en langue anglaise des bases de données PubMed et Cochrane. Les références bibliographiques de chaque article ont été également croisées à la recherche de nouvelles références.Constatations principalesLes filtres de réduction leucocytaire constituent une méthode efficace pour la suppression des cellules malignes dans le sang d’ICS. À ce jour, de petites études cliniques non randomisées n’ont pas fourni de données probantes sur une augmentation du taux de métastases ou de récidive cancéreuse. Bien qu’un risque théorique de récidive de la maladie persiste, la décision d’utilisation du sang autologue d’ICS doit être évaluée contre les riques connus d’une transfusion de sang allogène.ConclusionLa transfusion de sang autologue récupéré grâce à l’ICS doit être envisagé comme une option viable pour réduire ou éviter le recours à un produit allogène au cours de nombreuses chirurgies oncologiques; cela pourrait être également une option pour sauver la vie des patients qui refusent les produits sanguins allogènes.