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αβ T-cell lines specific for sulfatide, an abundant myelin glycosphingolipid presented by various CD1 molecules, have been previously derived from PBMCs of patients with demyelinating diseases such as multiple sclerosis (MS) but also from healthy subjects. Using an unbiased tetramer-based MACS enrichment method to enrich for rare antigen-specific cells, we confirmed the presence of CD1d-sulfatide-specific T cells in all healthy individuals examined. Surprisingly, the great majority of fresh sulfatide-specific T cells belonged to the γδ lineage. Furthermore, these cells used the Vδ1 TCR variable segment, which is uncommon in the blood but predominates in tissues such as the gut and specifically accumulates in MS lesions. Recombinant Vδ1 TCRs from different individuals were shown to bind recombinant CD1d-sulfatide complexes in a sulfatide-specific manner. These results provide the first direct demonstration of MHC-like-restricted, antigen-specific recognition by γδ TCRs. Together with previous reports, they support the notion that human Vδ1 T cells are enriched in CD1-specific T cells and suggest that the Vδ1 T-cell population that accumulates in MS lesions might be enriched in CD1-sulfatide-specific cells.

Type 1 diabetes (T1D) results from autoimmune destruction of the pancreatic βcells. Although all T1D patients require daily administration of exogenous insulin, their insulin requirement to achieve good glycaemic control may vary significantly. Glycated haemoglobin (HbA1c) level represents a stable indicator of glycaemic control and is a reliable predictor of long-term complications of T1D. The purpose of this article is to systematically review the role of non-genetic predictors and genetic factors of HbA1c level in T1D patients after the first year of T1D, to exclude the honeymoon period. A total of 1974 articles published since January 2011 were identified and 78 were finally included in the analysis of non-genetic predictors. For genetic factors, a total of 277 articles were identified and 14 were included. The most significantly associated factors with HbA1c level are demographic (age, ethnicity, and socioeconomic status), personal (family characteristics, parental care, psychological traits...) and features related to T1D (duration of T1D, adherence to treatment …). Only a few studies have searched for genetic factors influencing HbA1c level, most of which focused on candidate genes using classical genetic statistical methods, with generally limited power and incomplete adjustment for confounding factors and multiple testing. Our review shows the complexity of explaining HbA1c level variations, which involves numerous correlated predictors. Overall, our review underlines the lack of studies investigating jointly genetic and non-genetic factors and their interactions to better understand factors influencing glycaemic control for T1D patients.

The S1P1 receptor, on the surface of lymphocytes and endothelial cells, regulates the unique trafficking behavior of certain lymphocyte populations. We have examined whether the S1P1 receptor also dictates the distinctive tissue distribution of V alpha14-J alpha18 natural killer T (NKT) cells, whose trafficking pattern is not well understood. Mice (TCS1P1 KO) were established with a conditional deletion of the S1P1 receptor in thymocytes that included precursors of NKT cells. Within the thymus, NKT cells were found at normal or increased levels, indicating that S1P1 receptor expression was dispensable for NKT cell development. However, substantially reduced numbers of NKT cells were detected in the peripheral tissues of the TCS1P1 KO mice. Short-term S1P1 deletion after NKT cells had established residence in the periphery did not substantially alter their distribution in tissues, except for a partial decrease in the spleen. FTY720, a S1P1 receptor ligand that has potent effects on the trafficking of conventional T cells, did not alter the preexisting distribution of NKT cells within peripheral tissues of wild-type mice. Our results indicate that the S1P1 receptor expression on NKT cells is dispensable for development within thymus but is essential for the establishment of their tissue residency in the periphery.

The expression pattern of mouse CD1d and the tissue distribution of CD1d-restricted Valpha14-Jalpha281 NKT cells suggest that the liver and the marginal zone of the spleen might be preferred sites of activation of this potent innate pathway of early cytokine secretion. Because these tissues are particularly involved with the filtration of blood-borne pathogens, and because NKT cells with an activated / memory phenotype accumulate over the first weeks of life and their CD1 ligands bind microbial glycolipids, it has been hypothesized that expansion of the NKT cell subset may be driven by exposure to the microbial environment. To test this hypothesis, we analyzed the frequency, surface phenotype and functional properties of NKT cells in normal and in germ-free C57BL / 6 mice. Surprisingly, we found that the NKT cell subset develops in the presence or absence of a microbial environment. Although these results do not rule out the possibility that NKT cells exert a protective function against some microbial agents, they demonstrate that non microbial ligands, possibly self-antigens are sufficient for the generation, maturation and peripheral accumulation of NKT cells.

Both thymic and extrathymic bone marrow (BM)-derived pathways for the development of CD1 reactive, Valpha14-Jalpha281(+) NK1.1(+) T cells have been suggested. In this report, we sought evidence for extrathymic NK-T cell development using two approaches. First, BM cells from gammac-deficient mice were examined for the presence of Valpha14-Jalpha281 transcripts. Since intrathymic NK-T cell selection is gammac independent, we predicted that gammac(-) BM cells should also harbor these specific TCRalpha chains. Second, Valpha14-Jalpha281 transcripts were analyzed in BM cells from lethally irradiated, thymectomized mice reconstituted with fetal liver hematopoietic precursors. All donor-derived T cell development in these chimeras is by definition extrathymic. In both cases, we failed to detect invariant Valpha14(+) TCRalpha chain transcripts. These experiments call into question the significance of an extrathymic pathway of development for Valpha14(+) NK1.1(+) CD1-reactive T cells.

The levels of anti-human and anti-porcine factor VIII inhibitors, measured in 63 severe haemophilia A patients, lay in the ranges of < 0.2-2,600 and < 0.2-1,300 Bethesda units per ml (BU/ml), respectively, with a median cross-reactivity of 33%. In 4 patients, human and porcine inhibitor levels were determined using both plasma, either human or porcine, and factor VIII concentrate, either very high purity human or porcine (Hyate:C). A good correlation between titres was found, whatever the source of factor VIII (plasma or concentrate). The cross-reactivity varies from 0 to over 100%, indicating that the evaluation of both human and porcine inhibitors should be mandatory before any treatment with Hyate:C. Results show that of the 46 patients with human inhibitor of more than 5 BU/ml, 21 (46%) with a low porcine inhibitor (< 5 BU/ml) could benefit from Hyate:C.

Non-obese diabetic (NOD) mice become spontaneously diabetic as a result of a genetically programmed autoimmune process mediated by autoreactive T lymphocytes and directed against beta cell antigen(s). Studies dealing with T cell receptor (TcR) variable (V) gene usage by such autoreactive T lymphocytes have given contrasted results. Various reasons may explain these discrepancies: the multiplicity of antigenic epitopes putatively recognized by T cells, the ambiguity between specifically committed T cells and passenger lymphocytes homing randomly to the pancreas, the necessarily limited size of the T cell clone panels which have been analyzed for TcR rearrangements and, last but not least, the flexibility of T cell repertoires. To circumvent some of these difficulties, we have decided to concentrate upon the T cell population present in diseased animals and capable of transferring diabetes into young naive NOD recipients. This population, composed of CD4+ and CD8+ T cells, is presumably committed against the relevant beta cell antigens and is the most likely to reveal a bias in V gene usage if such a bias does indeed exist. To find out whether certain V beta genes are more frequently used than others by such pathogenic T cells, T lymphocytes from diabetic donors have been depleted in vitro of defined V beta subsets before being reinoculated into permissive recipients. Out of four V beta families probed under such conditions, three (V beta 8, V beta 5 and V beta 11) are neutral. Their absence neither increases nor reduces the final incidence of successful transfers, indicating that these gene segments are not preferentially used. In contrast, the depletion of V beta 6-positive T cells results in a severe reduction of transfers, suggesting that V beta 6 gene is used with a relatively high frequency by diabetogenic CD4+ and/or CD8+ T cells. To define more precisely which subset uses V beta 6 gene preferentially, we have performed mixing experiments with deleted and intact subsets. The results, based on disease transfer and insulitis severity, indicate that the V beta 6 bias affects predominantly the CD4+ subset. Thus, at variance with several studies concluding that V gene usage in NOD mice is heterogeneous, our present data suggest that disease transferring T cells use a relatively restricted set of V beta genes.

Although peripheral naive cells only secrete IL-2 upon primary stimulation, their presumptive immediate precursors, HSAlow CD4+8- thymocytes, can produce a large amount of the set of lymphokines usually associated with preactivated or memory CD4+ lymphocytes: IL-4, IL-5, IL-10 and gamma-IFN. This phenotype can be attributed to true virgin thymocytes and not only to recirculating lymphocytes, because it is found in newborn thymuses and in fetal thymic organ culture. This mature stage of CD4+8- thymocytes is itself preceded by an immature stage (HSAhigh) where only IL-2 and small amounts of gamma-IFN can be elicited by the combination of calcium ionophore and phorbol ester, but not by TCR cross-linking. CD8+4- thymocytes pass through a similar immature HSAhigh stage, where their pattern of lymphokine secretion is not yet differentiated from that of CD4+8- HSA high thymocytes. The subsets acquire their specific profiles at the HSAlow stage. We propose that recent thymic CD4+8- emigrant cells include a significant proportion of Th0 type cells, and that their role is critical to prime the immune system for IL-4 production, as well as to explain the longstanding observations of synergy between helper cell subpopulations in the periphery.

To overcome the limitations of in situ studies during the chronic spontaneous autoimmune process leading to insulin cell destruction and diabetes in non-obese diabetic (NOD) mice, we have developed a model of acute transfer of diabetes into healthy syngeneic newborns. The injection of 20 x 10(6) T cells from adult diabetic mice produced synchronous insulitis within 3 weeks and diabetes within 4-5 weeks in young recipients, at a time when non-injected control mice do not even exhibit histological changes in their pancreases. Sequential studies of pancreases from T cell-transferred mice showed that lymphoid infiltration was preceded by a strong tissue expression of Ia antigen which was restricted to the vessel-associated cells limiting the islet of Langerhans, and which might play a role in the recruitment of circulating T cells inside the islets. Acute destruction of most of the insulin-producing cells, leading to diabetes, could take place within a few days after insulitis had begun. A majority of the inflammatory cells were T lymphocytes, approximately 30% of which expressed interleukin 2 receptors. L3T4+ T cells largely predominated at the early phase of islet invasion whereas the proportion of Ly-2+ T cells substantially increased later when beta cell destruction occurred. In contrast, only a minority of B cells and macrophages participated to the inflammatory process. These data are in keeping with previous demonstrations that both T cell subsets contribute to the autoimmune disease. Furthermore, they suggest that beta cell injury is mediated through a cytotoxic process, which requires the sequential involvement of L3T4+ (helper) and Ly-2+ (cytotoxic) T cells.