Loss of immune tolerance to IL-2 in type 1 diabetes.

Type 1 diabetes (T1D) is characterized by a chronic, progressive autoimmune attack against pancreas-specific antigens, effecting the destruction of insulin-producing β-cells. Here we show interleukin-2 (IL-2) is a non-pancreatic autoimmune target in T1D. Anti-IL-2 autoantibodies, as well as T cells specific for a single orthologous epitope of IL-2, are present in the peripheral blood of non-obese diabetic (NOD) mice and patients with T1D.

Materno-Fetal Transfer of Preproinsulin Through the Neonatal Fc Receptor Prevents Autoimmune Diabetes.

The first signs of autoimmune activation leading to β-cell destruction in type 1 diabetes (T1D) appear during the first months of life. Thus, the perinatal period offers a suitable time window for disease prevention. Moreover, thymic selection of autoreactive T cells is most active during this period, providing a therapeutic opportunity not exploited to date.

Short-term subcutaneous insulin treatment delays but does not prevent diabetes in NOD mice.

Despite encouraging results in the NOD mouse, type 1 diabetes prevention trials using subcutaneous insulin have been unsuccessful. To explain these discrepancies, 3-week-old NOD mice were treated for 7 weeks with subcutaneous insulin at two different doses: a high dose (0.5 U/mouse) used in previous mouse studies; and a low dose (0.

Immunology of Diabetes Society T-Cell Workshop: HLA class II tetramer-directed epitope validation initiative.

Background: Islet-antigen-specific CD4+ T cells are known to promote auto-immune destruction in T1D. Measuring T-cell number and function provides an important biomarker. In response to this need, we evaluated responses to proinsulin and GAD epitopes in a multicentre study.

acDCs enhance human antigen-specific T-cell responses.

Detection of human Ag-specific T cells is limited by sensitivity and blood requirements. As dendritic cells (DCs) can potently stimulate T cells, we hypothesized that their induction in PBMCs in situ could link Ag processing and presentation to Ag-specific T-cell activation. To this end, unfractionated PBMCs (fresh or frozen) or whole blood were incubated for 48 hours with protein or peptide Ag together with different DC-activating agents to rapidly and sequentially induce, pulse, and mature DCs.

Autoimmunity during thymectomy-induced lymphopenia: role of thymus ablation and initial effector T cell activation timing in nonobese diabetic mice.

Autoimmune diseases develop in selected normal mouse strains when thymectomy (Tx) is performed at 3 days of age (d3-Tx). Insufficient T cell regulation after Tx may result from a defect in regulatory T (Treg) cells or from an augmented effector T (Teff) cell number/pathogenicity. We have previously shown that Tx at 3 wk (wk3-Tx), the age of massive islet Ag release, accelerates diabetes onset.

Lymphopenia-induced spontaneous T-cell proliferation as a cofactor for autoimmune disease development.

Lymphopenia is thought to be a major cause of tolerance breakdown. In a lymphopenic environment, self-recognition events induce some T cells to expand strongly (a mechanism known as spontaneous proliferation). In this study, we show that in C57BL/6 mice, the repertoire resulting from lymphopenia-induced spontaneous CD4(+) T-cell proliferation included a proportion of regulatory T cells as large as that observed in a normal mouse, and no autoimmune disorder was observed.

Influence of a non-NK complex region of chromosome 6 on CD4+ invariant NK T cell homeostasis.

The number and function of immunoregulatory invariant NKT (iNKT) cells are genetically controlled. A defect of iNKT cell ontogeny and function has been implicated as one causal factor of NOD mouse susceptibility to type 1 diabetes. Other factors of diabetes susceptibility, such as a decrease of regulatory T cell function or an increase in TLR1 expression, are corrected in diabetes-resistant Idd6 NOD.

The diabetes type 1 locus Idd6 modulates activity of CD4+CD25+ regulatory T-cells.

The genetic locus Idd6 confers susceptibility to the spontaneous development of type 1 diabetes in the NOD mouse. Our studies on disease resistance of the congenic mouse strain NOD.C3H 6.

Passive transfer of flt-3L-derived dendritic cells delays diabetes development in NOD mice and associates with early production of interleukin (IL)-4 and IL-10 in the spleen of recipient mice.

CD11c+/CD11b+dendritic cells (DC) with high levels of major histocompatibility complex (MHC) class II and co-stimulatory molecules have been derived from spleen cells cultured with granulocyte-macrophage colony stimulating factor (GM-CSF) + flt-3L + interleukin (IL)-6 (flt-3L-DC). Investigating in vivo the function of DC in non-obese diabetic mice (NOD), we showed that a single injection of this in vitro-derived subset of DC prevents the development of diabetes into prediabetic female mice. In contrast, DC derived from bone marrow cells cultured with GM-CSF + IL-4 [bone marrow (BM)-DC] induced no protection.

Pancreatic lymph nodes are required for priming of beta cell reactive T cells in NOD mice.

Nonobese diabetic (NOD) mice develop spontaneous autoimmune diabetes that results from the destruction of insulin secreting beta cells by diabetogenic T cells. The time and location of the encounter of autoantigen(s) by naive autoreactive T cells in normal NOD mice are still elusive. To address these issues, we analyzed diabetes development in mice whose spleen or pancreatic lymph nodes (panLNs) had been removed.

Characterization of peripheral regulatory CD4+ T cells that prevent diabetes onset in nonobese diabetic mice.

The period that precedes onset of insulin-dependent diabetes mellitus corresponds to an active dynamic state in which pathogenic autoreactive T cells are kept from destroying beta cells by regulatory T cells. In prediabetic nonobese diabetic (NOD) mice, CD4+ splenocytes were shown to prevent diabetes transfer in immunodeficient NOD recipients. We now demonstrate that regulatory splenocytes belong to the CD4+ CD62Lhigh T cell subset that comprises a vast majority of naive cells producing low levels of IL-2 and IFN-gamma and no IL-4 and IL-10 upon in vitro stimulation.

Growth hormone (GH) and prolactin receptors in human peripheral blood mononuclear cells: relation with age and GH-binding protein.

GH receptors (GHRs) and PRL receptors (PRLRs) were studied in human peripheral blood mononuclear cells (PBMC) using flow cytometry, biotinylated anti-GH receptor monoclonal antibody 10B8, and biotinylated human PRL. Variations of GHR and PRLR expression and the relationship of plasma GHBP and GH receptor in PBMC subsets were examined as a function of age and sex. By double immunofluorescence staining, we show that about 30% of total cells express GH receptors, with a low expression in T cells, whereas almost all B cells and monocytes are GH receptor positive.

Growth hormone and its receptor are expressed in human thymic cells.

GH has been shown to modulate various functions of the thymus. We now demonstrate the production of human GH (hGH) by human thymic cells, and the expression of GH receptors in thymic epithelial cells (TEC) and in thymocytes at different stages of differentiation. The presence of hGH messenger RNA was shown by RT-PCR in both human thymocytes and in primary cultures of TEC.

Role of adhesion molecules in the homing and mobilization of murine hematopoietic stem and progenitor cells.

Bone marrow (BM) transplantation still must overcome multiple difficulties and should benefit from better understanding of stem-cell homing and mobilization. Here, we analyzed the involvement of several adhesion molecules in the two processes by treating mice with monoclonal antibodies against these molecules. Treatment of lethally irradiated mice grafted with isogeneic BM cells showed that at least two migration pathways are important for stem-cell homing to the BM, whereas only one of them is involved in lodging of colony-forming unit-spleen (CFU-S) in the spleen.

Growth hormone receptors and immunocompetent cells.

Growth hormone plays a significant role in regulation of the humoral and cellular immune responses in physiological as well as pathological situations. This role is exerted via the existence of specific receptors on cells of the immune system. Using flow cytofluorometry and biotinylated bovine GH, we have recently analyzed the expression of GH receptors (GHRs) in murine lymphoid organs.

L-selectin(-/lo) and diabetogenic T cells are similarly distributed in prediabetic and diabetic nonobese diabetic mice.

We have previously shown that in the nonobese diabetic (NOD) mouse, an experimental model for autoimmune insulin-dependent diabetes, spleen diabetogenic T cells are contained within the T-cell subpopulation that express no or low levels of L-selectin. This phenotype characterizes activated/memory T cells. In the present study, we have compared the distribution of autoreactive T cells to that of L-selectin -/lo T cells in prediabetic and diabetic mice.

Growth hormone stimulates the proliferation of activated mouse T lymphocytes.

A modulatory role for GH on immune function has been suggested, but hormonal effects have been difficult to demonstrate with isolated cells. We have recently shown that GH receptors are present in murine hematopoietic tissues, with a lower receptor number in T lymphocytes than in B cells or macrophages. The binding of bovine GH (bGH) to murine splenocytes is increased after T cell activation with either concanavalin A or anti-CD3 antibody.

Expression of growth hormone receptors in murine lymphoid cells analyzed by flow cytofluorometry.

We have analyzed the expression of GH receptors (GHR) in murine lymphoid organs using flow cytofluorometry with biotinylated bovine GH and specific fluorescein isothiocyanate-labeled monoclonal antibodies defining distinct lymphoid cell populations. GHR were widely expressed in al murine hematopoietic tissues and in fetuses, newborns, and 3- and 7-week-old animals. In the bone marrow, all hematopoietic lineages expressed variable levels of GH receptors, whereas in the thymus, this expression was mainly seen in CD4-, CD8-, CD4+CD8+, and CD8+ subpopulations.

Homing of lymphocytes into islets of Langerhans in prediabetic non-obese diabetic mice is not restricted to autoreactive T cells.

Non-obese diabetic mice spontaneously develop a type 1 diabetes. The entry of leukocytes in the islets of Langerhans was studied in untreated and in irradiated mice. FITC-labeled cells from spleen, lymph nodes or bone marrow of healthy or diabetic donors did home to the inflamed islets of unmanipulated recipients.

Isolation of leukocytes infiltrating the islets of Langerhans of diabetes-prone mice for flow cytometric analysis.

A simple method was developed for flow cytometric immunofluorescence analysis of cells infiltrating the islets of Langerhans in diabetes-prone rodents. Pancreases were submitted to collagenase P digestion and, in order to minimize collagenase action on leukocytes, islets were isolated before digestion was completed, that is, when exocrine tissue still remained around the islets. Islets, maintained in medium supplemented with sodium azide to prevent modulation of surface markers, were then pressed through a metal sieve and the cell suspension filtered through two different nylon screens.

Reduced ability of hypothalamic and pituitary extracts from old mice to stimulate thymulin secretion in vitro.

There is substantial evidence that growth hormone (GH) is particularly important in the control of the age-related decline of thymus function. It was therefore of interest: (a) to assess the overall capacity of tissue extracts from mediobasal hypothalamus (MBH), anterior pituitary (AP) and testis, obtained from young (3 months, Yc), middle-aged (13 months, MAc) and old (18 months, Oc) intact C57BL/6 mice to stimulate in vitro the release of thymulin, a Zn-bound immunoregulatory thymic peptide, from pure cultures of mouse thymic epithelial cells (TEC); (b) to perform the same evaluation utilizing MBH, AP and testicular extracts from mice of the same age-range but treated for 45 days with a sc dose of ovine GH (2 micrograms/g body wt) known to stimulate thymulin secretion in vivo. Pituitary hormones were measured by heterologous rat RIAs, whereas thymulin release was estimated by a rosette assay.

Lack of L-selectin expression by cells transferring diabetes in NOD mice: insights into the mechanisms involved in diabetes prevention by Mel-14 antibody treatment.

The process of mononuclear cell extravasation from the blood into the islets of Langerhans in nonobese diabetic (NOD) mice is dependent on the expression of a set of molecules, most of which remain to be defined. The observation that vascular addressins are expressed in inflamed islets raises the issue of the involvement of one of their ligands, L-selectin, in the pathogenesis of autoimmune diabetes. Treatment of NOD females with Mel-14, an antibody specific for L-selectin, reduced the spontaneous development of both insulitis and diabetes.

Two different mechanisms for the inhibition of rosette formation in mice.

The vast majority of spleen T cells (T.sRFC) which spontaneously bind to sheep red blood cells (SRBC) in an antigen-specific fashion express the Thy-1+, CD3+, CD8+ phenotype. Inhibition of rosetting by antibodies to surface molecules occurs via distinct mechanisms according to the antibody.

Prolactin receptors and the immune system.

The existence of a physiological immunoneuroendocrine network clearly contributing to homeostasis has now been demonstrated. In this context, nervous, endocrine, and immune systems communicate with each other, using common mediators and respective receptors. An interesting aspect of this network involves the interactions between prolactin (PRL) and the immune system.