Gammadelta T-cells alterations in the peripheral blood of high risk diabetes type 1 subjects with subclinical pancreatic B-cells impairment.

There is increasing evidence that CD3 + cells bearing gammadelta T-cell receptor (represent the minor subpopulation of the T-cells in the peripheral blood in humans) are involved in autoimmunity development. Gammadelta T-cell receptor (TCR)+ /CD8+ T-cells have been recently found to play a critical role in the pathogenesis and prevention of autoimmune diabetes in the animal model. The aim of the present study was the estimation the gammadelta T-cell subpopulation levels in the peripheral blood of subjects with preclinical and overt type 1 diabetes and their possible associations with the humoral immunity, metabolic parameters and pancreatic B-cells function. The study was carried out in three groups of subjects: 26 first degree relatives of type 1 diabetes patients (prediabetics) with the combinations of autoantibodies against pancreatic B-cells (ICA, GADA, IA-2A, IAA), 22 patients with a recent onset of type 1 diabetes and age and sex-matched 24 healthy volunteers (control group). A decrease was observed in the absolute numbers and percentages of gammadelta+ /CD8+ and gammadelta+ /CD8- T-cell subpopulations in peripheral blood in the prediabetics with the impaired first phase of insulin secretion in comparison to relatives with autoantibodies but still with normal B-cells function, patients with clinical diabetes and healthy controls. In conclusion, the study suggests that the gammadelta T-cells play an important role in the development of insulin-dependent diabetes mellitus (IDDM). It is possible that their levels in the peripheral blood could be an additional marker of preclinical detection of the disease, but further prospective studies in high risk of IDDM subjects are needed.     

Prevention of autoimmune insulin-dependent diabetes in non-obese diabetic mice by anti-LFA-1 and anti-ICAM-1 mAb

Diverse adhesion molecules participate in many important responsesand thus would be implicated in the pathogenesis of variousautoimmune diseases. However, there is little evidence for therole of these molecules in autoimmune insulin-dependent diabetesmellitus. Here we present several lines of evidence suggestingthat leukocyte function-associated antlgen-1 (LFA-1) and itscounter-receptor intercellular adhesion molecules (ICAM-1),one of the most important pairs among these adhesion molecules,are involved in the development of autoimmune diabetes in thenon-obese diabetic (NOD) mouse. Immunohlstochemlcal study showedthe hyperexpresslon of ICAM-1 on islet-lnflltratlng mononuclearcells and vascular endothellum in NOD pancreas. In vivo administrationof antl-LFA-1 or antl-ICAM-1 mAb from 5 to 30 (or 12) weeksof age exerted a very strong preventatlve effect on the developmentof spontaneous diabetes with a marked reduction of insulitis,whereas both antibodies, even combined to use simultaneously,could not prevent cyclophosphamide-lnduced diabetes. Adoptivetransfer of insulitis and diabetes to young NOD mice followingthe injection of islet-derived mononuclear cells from diabeticdonors was completely blocked by administration of both antibodiesto recipients. The present study, therefore, provides the firstevidence that immunolnterventlon to LFA-1 - ICAM-1 Interactionhas a strong prophylactic effect on autoimmune diabetes in NODmice.     

Elimination of CD4+ CD25+ regulatory T cells breaks down reovirus type 2-triggered and CpG ODN-induced prolonged mild autoimmune insulitis in DBA/1 mice

We have reported previously that subclinical prolonged mild T helper (Th) 1-dependent autoimmune insulitis with impaired glucose tolerance in wealing DBA/1J mice, which is induced by the combined effects of reovirus type 2 (Reo-2) and synthetic 20-base oligodeoxynucleotides with CpG motifs (CpG ODN) (control mice). Compared with the control mice, newborn mice treated with monoclonal antibody (MoAb) against mouse CD25(+) CD4(+) T cells together with Reo-2 and CpG ODN greatly reduced the absolute number of splenic CD25(+) T cells and resulted in the development of severe insulitis, leading to an overt early diabetes. Moreover, the treatment of the MoAb increased production of interferon-gamma (IFN-gamma) and decreased that of interleukin-4 (IL-4) and transforming growth factor-beta1 (TGF-beta1) and developed high titre of autoantibodies against pancreatic islet cells. These evidences suggest that CD4(+) CD25(+) T cell may, at least in part, maintain tolerance to Reo-2-triggered and CpG ODN-induced prolonged mild Th1-dependent autoimmune insulitis, leading to the overt disease. This system may give a novel model to elucidate the mechanisms of the development of overt diabetes from borderline subclinical diabetes in virus-triggered autoimmune type I diabetes in human.     

Beta-cell, thyroid, gastric, adrenal and coeliac autoimmunity and HLA-DQ types in type 1 diabetes.

The autoimmune attack in type 1 diabetes is not only targeted to beta cells. We assessed the prevalence of thyroid peroxidase (aTPO), parietal cell (PCA), antiadrenal (AAA) and endomysial antibodies (EmA-IgA), and of overt autoimmune disease in type 1 diabetes, in relation to gender, age, duration of disease, age at onset, beta-cell antibody status (ICA, GADA, IA2A) and HLA-DQ type. Sera from 399 type 1 diabetic patients (M/F: 188/211; mean age: 26 +/- 16 years; duration: 9 +/- 8 years) were tested for ICA, PCA, AAA and EmA-IgA by indirect immunofluorescence, and for IA2A (tyrosine phosphatase antibodies), GADA (glutamic acid decarboxylase-65 antibodies) and aTPO by radiobinding assays. The prevalence rates were: GADA 70%; IA2A, 44%; ICA, 39%; aTPO, 22%; PCA, 18%; EmA-IgA, 2%; and AAA, 1%. aTPO status was determined by female gender (beta = - 1.15, P = 0.002), age (beta = 0.02, P = 0.01) and GADA + (beta = 1.06, P = 0.02), but not by HLA-DQ type or IA2A status. Dysthyroidism (P < 0.0001) was more frequent in aTPO + subjects. PCA status was determined by age (beta = 0.03, P = 0.002). We also observed an association between PCA + and GADA + (OR = 1.9, P = 0.049), aTPO + (OR = 1.9, P = 0.04) and HLA DQA1*0501-DQB1*0301 status (OR = 2.4, P = 0.045). Iron deficiency anaemia (OR = 3.0, P = 0.003) and pernicious anaemia (OR = 40, P < 0.0001) were more frequent in PCA + subjects. EmA-IgA + was linked to HLA DQA1*0501-DQB1*0201 + (OR = 7.5, P = 0.039), and coeliac disease was found in three patients. No patient had Addison's disease. In conclusion, GADA but not IA2A indicate the presence of thyrogastric autoimmunity in type 1 diabetes. aTPO have a female preponderance, PCA are weakly associated with HLA DQA1*0501-DQB1*0301 and EmA-IgA + with HLA DQA1*0501-DQB1*0201.     

Soluble ICAM-1 as a regulator of nasal allergic reaction under natural allergen provocation

Background: Intercellular adhesion molecule-1 (ICAM-1) plays a key role in the early stage of the signal cascade leading to cellular extravasation and the development of an inflammatory response. Recently, it has been reported that the soluble form of this adhesion molecule is present in human sera, possibly mediating biological actions.
Objective: The purpose of this study was to investigate levels of soluble ICAM-1 (sICAM-1) and its receptors in patients with allergic rhinitis, and to discuss sICAM-1's biological function.
Methods: The levels of sICAM-1 in sera and nasal epithelial lining fluids (ELF), the percentage of CD11a-positive lymphocytes in the peripheral blood, and scores of subjective symptoms from 14 patients with pollinosis (allergic group) were measured from pre- to post-season, results were compared with those from 10 non-allergic subjects (control group).
Results: The levels of sICAM-1 in sera and ELF were upregulated, and CD11a-positive lymphocytes were downregulatcd during the in-season in the allergic group. In addition, levels of sICAM-1 in sera from the allergic group remained high during the post-season, when levels of other parameters (symptoms, blood eosinophil counts, sICAM-1 in ELF and CD11a-positive lymphocytes) had roughly returned to the initial pre-season levels.
Conclusions: We demonstrate systemic and local upregulation of sICAM-1 and systemic downregulation of LFA-1 positive lymphocytes in patients with seasonal allergic rhinitis under natural allergen provocation, suggesting that sICAM-1 plays a role in regulating seasonal allergic inflammation.     

Decreased expression of adhesion molecules on monocytes in recent onset IDDM.

The expression of adhesion molecules in monocytes of patients with recent onset type I diabetes was analysed. Monocytes were identified as CD14-positive cells by flow cytometry. The percentage of monocytes expression LFA-1 alpha, ICAM-1 and HLA-DR was slightly lower in recent onset type I diabetes (n = 13) compared to normal subjects (n = 15) and was significantly decreased after activation of cells with lipopolysaccharide and interferon-gamma for 5-24 hr. Receptor densities on adhesion molecule-positive monocytes and the expression of LFA-1 beta were normal. These data indicate that monocyte trafficking is abnormal in recent onset type 1 diabetes.     

Soluble intercellular adhesion molecule-1 (sICAM-1) in sera of patients with Graves' ophthalmopathy and thyroid diseases.

Intercellular adhesion molecule, a ligand for the leucocyte integrins CD11a/CD18 (LFA-1) and CD11b/CD18 (Mac-1), that plays an important role in a variety of inflammatory and immune-mediated mechanisms, is strongly expressed in retroocular connective tissue from patients with Graves' ophthalmopathy (GO) and involved in lymphocyte attachment to cultured retroocular fibroblasts via the ICAM-1/LFA-1-mediated pathway. Here, we report the detection and functional activity of a soluble form of the ICAM-1 molecule (sICAM-1) in sera from patients with GO and other thyroid diseases. Serum concentrations for sICAM-1 were determined using a highly sensitive ELISA. Compared with normal controls, patients with hyperthyroid or euthyroid GO and patients with Riedel's invasive fibrous thyroiditis revealed markedly elevated sICAM-1 serum concentrations (all P < 0.0001). In patients with Graves' disease (GD) without clinical GO and in patients with Hashimoto's thyroiditis (HT), sICAM-1 levels were elevated to a lesser degree (both P < 0.001). sICAM-1 serum levels in patients with non-autoimmune hyperthyroidism due to a toxic adenoma were not significantly different from normal controls. In a separate group of 12 patients with severe inflammatory GO, sICAM-1 serum levels markedly declined (P < 0.0001) within 3 months of glucocorticoid therapy in nine patients who responded to this form of treatment with a decrease in periorbital inflammation. In contrast, sICAM-1 serum levels remained unchanged in three patients with poor response to steroids and persistent inflammatory periorbital disease. When tested in a cell adhesion assay, GO sera containing elevated concentrations of sICAM-1 were found to enhance the attachment of peripheral blood mononuclear cells (PBMC) to interferon-gamma (IFN-gamma)-treated retroocular fibroblasts in a dose-dependent manner, up to a maximal stimulation of approximately 5.5-fold (P < 0.001). This effect was abolished by preabsorption of sera with a MoAb against ICAM-1 and inhibited, in a dose-dependent manner, by coincubation with increasing concentrations of purified sICAM-1. In conclusion, sICAM-1 concentrations are markedly elevated in sera from patients with GO, and changes in sICAM-1 serum levels during glucocorticoid therapy closely parallel changes in the degree of inflammation. Given the capacity of sICAM-1 to modulate the adhesion of lymphocytes to retroocular fibroblasts in vitro, sICAM-1 may play a role in the ongoing immune process within the connective tissue in GO.     

Type 1 diabetes and prediabetic state in a monozygotic triplet

Type 1 diabetes mellitus (IDDM) results from a chronic process of autoimmune destruction of beta cells of the Langerhans islets. The presence of autoantibodies (ICA, GADA, anti-IA2, IAA) in serum precedes the clinical onset of the disease. Genetic predisposition for IDDM is connected with HLA, CTLA-4 and insulin gene region. The aim of the study was the genetic and immunological analysis of a triplet. One of them developed Type 1 diabetes mellitus. We analysed HLA class II, CTLA-4 and insulin gene polymorphisms in the whole family. Besides, we investigated immunological status of three brothers. All patients present identical genotype for VNTR loci: D1S80, D17S5 and Apo B, as well as for HLA-DRB1, -DQA1, -DQB1, CTLA-4 gene and all studied insulin gene polymorphisms. That proves their monozigosity. The triplet presents strong genetic predisposition for IDDM. The two patients without overt diabetes have increased levels of ICA, GADA, IA2 and IAA.     

In vitro secretion of interleukin 2 and expression of IL-2 receptor in peripheral blood lymphocytes in high risk of insulin-dependent diabetes mellitus subjects.

Interleukin 2 (IL-2)--a Th1 lymphocyte-derived cytokine is at present considered to play an important role in the etiopathogenesis of insulin-dependent diabetes mellitus. In the previous studies increased, decreased and unchanged IL-2 levels in patients with recent onset of insulin-dependent diabetes mellitus (IDDM) were found. These differences could be a result of different metabolic status or/and a different stage of the autoimmune process. The aim of our study was to estimate in vitro secretion of IL-2 and CD25 antigen expression by the peripheral blood T lymphocytes in subjects at the preclinical stage of IDDM (prediabetes), but still without metabolic disturbances. In 27 first degree relatives of IDDM patients with antibodies against different pancreatic islet cell antigens (ICA, GADA, IAA, IA-2) CD25 antigen expression on peripheral blood lymphocytes T was measured by flow cytometry and IL-2 concentration in supernatants of 48 and 72 h cultures of peripheral whole blood with 10 microg/ml PHA was estimated by ELISA. The control group was comprised of 34 age and sex-matched healthy volunteers. In the studied high risk IDDM subjects the decreased CD25 expression in peripheral CD4+ lymphocytes T and a negative correlation between the percentage of CD25+ cells and islet cell antibodies (ICA) titres was observed. No differences in IL-2 levels in supernatants of 48 h and 72 h blood cultures was found in subjects with single antibody (ICA+) in comparison to healthy controls. A significant increase of IL-2 secretion at 72 h of PHA stimulation was shown in first degree relatives of IDDM patients with a combination of 3 or more antipancreatic-B cell antibodies. There were also a significant negative correlation between glutamic acid decarboxylase antibodies (GADA) titres and IL-2 levels in 72 h of culture. The present study suggests the involvement of IL-2 in the pathogenesis of IDDM. The estimation of CD25 antigen expression in the peripheral blood lymphocytes could be an additional immunological marker of identification of subjects in prediabetes.     

LFA-1 and ICAM-1 molecule expression in jejunal mucosa from children with autoimmune enteropathy.

The expression of adhesion molecules by cells of the small intestinal mucosa was compared in gut biopsies from children with autoimmune small intestinal enteropathy and normal controls and related to HLA-DR expression by the same tissue. Jejunal biopsies were stained by IFL with monoclonal antibodies to LFA-1 (TS1/22 and CD11a/25.3.1) and ICAM-1 (RR1/1 and 84H10) molecules. LFA-1 and ICAM-1 positive cells were observed in the lamina propria in all cases and the counts were increased in autoimmune enteropathy compared with controls. In addition, in 4 of 7 cases of autoimmune enteropathy crypt enterocytes were positives for ICAM-1 when stained with RR1/1 and 3 of the 4 were also positive for LFA-1 when stained with both LFA-1 reagents. We speculate on the role of adhesion molecule expression in autoimmune enteropathy.     

Contribution of CD11a/CD18, CD11b/CD18, ICAM-1 (CD54) and −2 (CD102) to human monocyte migration through endothelium and connective tissue fibroblast barriers

Recently we reported that monocyte migration through a barrier of human synovial fibroblasts (HSF) is mediated by the CD11/CD18 (β₂) integrins, and the β₁ integrins VLA-4 and VLA-5 on monocytes. Here we investigated in parallel the role of β₂ integrin family members, LFA-1 (CD11a/CD18) and Mac-1 (CD11b/CD18) on monocytes, and the immunoglobulin supergene family members, ICAM-1 and ICAM-2 on HSF and on human umbilical vein endothelial cells (HUVEC), in monocyte migration through HSF and HUVEC monolayers. Using function blocking monoclonal antibodies (mAb), when both VLA-4 and VLA-5 on monocytes were blocked, treatment of monocytes with mAb to both LFA-1 and to Mac-1 completely inhibited monocyte migration across HSF barriers, although blocking either of these β₂ integrins alone had no effect on migration, even when VLA-4 and VLA-5 were blocked. This indicates that optimal β₂ integrin-dependent monocyte migration in synovial connective tissue may be mediated by either LFA-1 or Mac-1. Both ICAM-1 and ICAM-2 were constitutively expressed on HSF and on HUVEC, although ICAM-2 was only minimally expressed on HSF. Based on results of mAb blockade, ICAM-1 appeared to be the major ligand for LFA-1-dependent migration through the HSF. In contrast, both ICAM-1 and ICAM-2 mediated LFA-1-dependent monocyte migration through HUVEC. However, neither ICAM-1 nor ICAM-2 was required for Mac-1-dependent monocyte migration through either cell barrier, indicating that Mac-1 can utilize ligands distinct from ICAM-1 and ICAM-2 on HSF and on HUVEC during monocyte transmigration.     

Effect of antibodies to intercellular adhesion molecule (ICAM)-1 and lymphocyte function-associated antigen (LFA)-1 on cytokine mRNA expression in reovirus type-2-triggered autoimmune insulitis in suckling DBA/1 mice

Interleukin (IL)-12 in the presence of IL-18 induces T helper (Th) 1 dominated systemic immune reactions, such as those that occur in autoimmune insulitis in suckling mice infected with reovirus type-2 (Reo-2). The role of intercellular adhesion molecule (ICAM)-1 and lymphocyte function-associated antigen (LFA)-1 on the induction of cytokines responsible for Reo-2-triggered insulitis with impaired glucose tolerance (IGT) was examined. One-day-old DBA/1 mice infected with Reo-2 intraperitoneally (i.p.) were treated i.p. with monoclonal antibodies (mAbs) against ICAM-1 and LFA-1 (ICAM-1/LFA-1) at 5 days post-infection (d.p.i.). At 10 d.p.i., the administration of the mAbs was seen to have prevented the development of insulitis with IGT. This was associated with a decrease in the mRNA expression for IL-12(p40) and IL-18 by splenic cells. The present study suggests that ICAM-1/LFA-1 may be required for the differentiation of Th0 cells to Th1 cells, which mediate insulitis with IGT in Reo-2-infected suckling mice.     

Engagement of ICAM-1 by major group rhinoviruses activates the LFA-1/ICAM-3 cell adhesion pathway in mononuclear phagocytes

Cell-cell interactions are critical at key points of immune responses and are mediated by a complex array of adhesion receptors. One of the most important adhesion molecules on leukocytes is intercellular adhesion molecule 1 (ICAM-1, CD54). Here we demonstrate that engagement of ICAM-1 with human major group rhinoviruses (HRV) enhances adhesiveness and homotypic aggregation of human monocytes and monocyte-derived dendritic cells (DC). Cluster formation upon engagement of ICAM-1 with HRV14 represents an active process. It is temperature and energy dependent, requires divalent cations, an intact cytoskeleton and protein de novo synthesis. Homotypic interaction between monocytes induced by HRV14 can be inhibited with blocking mAbs against LFA-1 (CD11a/CD18) and ICAM-3 (CD50) as well as with a mAb against the first immunoglobulin (Ig)-domain of PECAM-1 (CD31). Induction of enhanced cytoadhesiveness by HRV14 was not accompanied with an upregulation of LFA-1, ICAM-3 or PECAM-1 expression. Binding studies with recombinant PECAM-1 proteins indicated, however, that monocyte clustering upon engagement of ICAM-1 with HRV was accompanied with increased homophilic PECAM-1 interactions. Taken together the results of our study demonstrate that signalling via ICAM-1 induces adhesiveness of mononuclear phagocytes, which critically involves PECAM-1 and is mediated via LFA-1/ICAM-3.     

CD23 antigen expression on B lymphocytes and soluble CD23 levels in peripheral blood of high-risk type 1 diabetes subjects

Soluble CD23 (sCD23), a recently discovered multifunctional cytokine, is a 25-kDa molecule released by autoproteolysis from the 45-kDa CD23 molecule which is found mainly on the surface of B lymphocytes. In the present study we aimed to evaluate, in association with humoral immune and metabolic markers, the changes in CD23 antigen expression on B lymphocytes and levels of sCD23 in the peripheral blood of subjects at high risk of type 1 diabetes. The study was carried out in 28 first-degree relatives of type 1 diabetes patients (versus a control group of 28 age- and sex-matched healthy volunteers) using antibodies against different B-cell antigens: ICA, GADA, IAA, IA-2. Flow cytometry was used to measure the percentage of CD20+ (B lymphocytes) and CD20+CD23+ lymphocyte subsets, and sCD23 levels in serum were determined by enzyme immunoassay. Prediabetic subjects had a significantly (P<0.01) lower percentage of CD20+CD23+ lymphocytes in comparison with healthy age- and sex-matched controls. Expression of CD23+ on B lymphocytes was similar in subjects with ICA only and with two or more antibodies against pancreatic antigens. In the prediabetic group, the median concentration of sCD23 was lower than in the control group and was statistically significant (P < 0.02) in the subgroup of subjects with the most impaired function of pancreatic beta-cells (the lowest values of first phase of insulin release). In conclusion, our study suggests that CD23 molecule expression on B lymphocytes and sCD23 levels in peripheral blood could be additional markers for monitoring the development of type 1 diabetes and play a role in determining the efficacy of prevention trials. However, further prospective studies are needed.     

Characterization of human organ donors testing positive for type 1 diabetes-associated autoantibodies

In this study we aim to describe the characteristics of non-diabetic organ donors with circulating diabetes-associated autoantibodies collected within the Nordic Network for Islet Transplantation. One thousand and thirty organ donors have been screened in Uppsala for antibodies against glutamic acid decarboxylase (GADA) and islet antigen-2 (IA-2A). The 32 non-diabetic donors that tested positive for GADA (3·3% of all non-diabetic donors) were studied in more detail, together with 32 matched controls. Mean age among the autoantibody-positive donors was 52·6 (range 21–74), family history of type 1 diabetes (T1D) was unknown, and no donor was genetically predisposed for T1D regarding the human leucocyte antigen (HLA) locus. Subjects were analysed for islet cell antibodies (ICA), insulin autoantibodies (IAA) and zinc transporter 8 antibodies (ZnT8A), and pancreas morphology and clinical data were examined. Eight non-diabetic donors tested positive for two antibodies and one donor tested positive for four antibodies. No insulitis or other signs of a diabetic process were found in any of the donors. While inflammatory cells were present in all donors, subjects with high GADA titres had significantly higher CD45 cell numbers in exocrine tissue than controls. The extent of fibrosis was more pronounced in autoantibody-positive donors, even in subjects with lower GADA titres. Notably, it is possible that events not related directly to T1D (e.g. subclinical pancreatitis) may induce autoantibodies in some cases.     

1型糖尿病一级亲属GADA、IAA与ICA联检的临床意义

目的：探讨联检1型糖尿病（DM1）一级亲属谷氨酸脱羧酶抗体（GADA）、胰岛素自身抗体（IAA）和胰岛细胞抗体（ICA）的临床意义。方法：采用ELISA测定血清GADA、IAA及ICA。结果：一级亲属GADA、IAA、ICA的检出率均显著高于正常对照组，自身抗体联检的阳性率显著高于单抗体或双抗体阳性率。结论：联检可以提高DM1高危人群筛查的阳性率。     

Upregulation of adhesion molecules induced by broncho-vaxom on phagocytic cells.

Whole blood was incubated with the bacterial extract Broncho-Vaxom (OM85) at various concentrations and for different periods of time. Expression of the beta 2-integrins (LFA-1, CD11a/CD18; MAC-1, CD11b/CD18; p150,95, CD11c/CD18) and ICAM-1 (CD54) by monocytes and granulocytes was studied using flow cytometry. OM85 enhanced the expression of MAC-1 and ICAM-1 on monocytes and granulocytes in a dose-dependent manner. Maximal expression was achieved with 1 mg/ml bacterial extract. The effect on MAC-1 expression was not due to the low concentration of endotoxin contaminating the preparation (less than 1 ng/mg) since polymyxin-B did not substantially affect the adhesion molecule upregulation induced by OM85. In addition, OM85 enhanced the expression of p150,95 on monocytes and granulocytes, and also increased expression of LFA-1 on monocytes, but not on granulocytes. While MAC-1 and p150,95 expression reached peak values between 1 and 6 h, levels of ICAM-1 rose constantly for 10 h. We suggest that the clinical interest of OM85 in the management of recurrent infections could be related to be upregulation of adhesion molecules induced by this bacterial extract.     

Autoantibody markers for the diagnosis and prediction of type 1 diabetes

Type 1 diabetes results from the autoimmune destruction of the insulin producing pancreatic beta-cells. For years, the notion that T-lymphocytes played a crucial role in the disorder's formation was considered such sound dogma, that interest in B-lymphocytes and autoantibodies as pathogenic variables was largely relegated to second-class status. However, much of our knowledge regarding the pathogenesis and natural history of this disease has been afforded by analysis of subjects having type 1 diabetes associated autoantibodies. While autoantibodies to more than two dozen autoantigens have been associated with this disease, a majority of interest has been directed at four autoantibodies; islet cell cytoplasmic (ICA), insulin (IAA), glutamic acid decarboxylase (GADA), and IA2/ICA512 autoantigen (IA2A). These autoantibodies, combined with other metabolic and genetic markers, are extremely effective for predicting eventual development of type 1 diabetes in otherwise healthy individuals. These autoantibodies have also aided in our understanding of disease heterogeneity and suggest that the autoimmune processes underlying type 1 diabetes initiate in the earliest stages of life (e.g., initial autoantibody formation at 9-18 months of age). Additional improvements are needed to more accurately define the time to disease onset, response to therapeutic intervention, the pathogenic features of the autoimmune response, and perhaps even the quantity of residual beta cell function.     

Remote T cell co-stimulation via LFA-1/ICAM-1 and CD2/LFA-3: demonstration with immobilized ligand/mAb and implication in monocyte-mediated co-stimulation.

Proliferative response of resting T cells generally requires not only cross-linking of the T cell receptor (TcR) but also co-stimulatory signals from accessory molecules. We here have used a "three-cell" model consisting of: (a) resting human CD4+ T cells as responders; (b) CD3 monoclonal antibody (mAb) OKT3 on latex beads as surrogate stimulators; (c) autologous monocytes as source of co-stimulation. As described by Kawakami et al. (J. Immunol. 1989, 142: 1818), T cell proliferation in this system is observed with paraformaldehyde-fixed monocytes if they have been activated and interleukin (IL) 1 beta/IL 6 is supplied. Since this three-cell system provides TcR cross-linking at a site spatially "remote" from co-stimulation, they help distinguish adhesion from signal transduction but the molecules that mediate co-stimulation in this system have not been identified. Our studies now demonstrate that co-stimulation by the monocytes is dependent on each of two receptor/ligand pathways CD2/LFA-3 and LFA-1/ICAM-1 since it is inhibited by each relevant mAb but not a variety of control mAb. The hypotheses that CD2 and LFA-1 could each mediate co-stimulation was tested in simplified model systems in which the monocyte was replaced with immobilized CD2 mAb or purified ICAM-1 presented on a separate surface from the CD3 mAb. The results in these simplified models demonstrate that on resting T cells either CD2 or LFA-1 molecules alone can mediate "remote" co-stimulation unlike most other T cell surface molecules. Co-stimulation requires IL 1 beta/IL6 both in the weaker LFA-1 ligand-mediated co-stimulation and at lower CD2 mAb concentrations in the stronger CD2 mAb-mediated co-stimulation. Thus: (a) the accessory cell function of stimulated fixed monocytes in T cell proliferation requires both the LFA-1/ICAM-1 and CD2/LFA-3 pathways; and (b) the T cell molecules CD2 and LFA-1 can give co-stimulatory signals that can act in a "remote" fashion.