Alternative splicing encodes functional intracellular CD59 isoforms that mediate insulin secretion and are down-regulated in diabetic islets.

Human pancreatic islets highly express CD59, which is a glycosylphosphatidylinositol (GPI)-anchored cell-surface protein and is required for insulin secretion. How cell-surface CD59 could interact with intracellular exocytotic machinery has so far not been described. We now demonstrate the existence of CD59 splice variants in human pancreatic islets, which have unique C-terminal domains replacing the GPI-anchoring signal sequence. These isoforms are found in the cytosol of ß-cells, interact with SNARE proteins VAMP2 and SNAP25, colocalize with insulin granules, and rescue insulin secretion in CD59-knockout (KO) cells. We therefore named these isoforms IRIS-1 and IRIS-2 (Isoforms Rescuing Insulin Secretion 1 and 2). Antibodies raised against each isoform revealed that expression of both IRIS-1 and IRIS-2 is significantly lower in islets isolated from human type 2 diabetes (T2D) patients, as compared to healthy controls. Further, glucotoxicity induced in primary, healthy human islets led to a significant decrease of IRIS-1 expression, suggesting that hyperglycemia (raised glucose levels) and subsequent decreased IRIS-1 expression may contribute to relative insulin deficiency in T2D patients. Similar isoforms were also identified in the mouse CD59B gene, and targeted CRISPR/Cas9-mediated knockout showed that these intracellular isoforms, but not canonical CD59B, are involved in insulin secretion from mouse ß-cells. Mouse IRIS-2 is also down-regulated in diabetic db/db mouse islets. These findings establish the endogenous existence of previously undescribed non­GPI-anchored intracellular isoforms of human CD59 and mouse CD59B, which are required for normal insulin secretion.

Assisting the implementation of screening for type 1 diabetes by using artificial intelligence on publicly available data.

The type 1 diabetes community is coalescing around the benefits and advantages of early screening for disease risk. To be accepted by healthcare providers, regulatory authorities and payers, screening programmes need to show that the testing variables allow accurate risk prediction and that individualised risk-informed monitoring plans are established, as well as operational feasibility, cost-effectiveness and acceptance at population level. Artificial intelligence (AI) has the potential to contribute to solving these issues, starting with the identification and stratification of at-risk individuals. ASSET (AI for Sustainable Prevention of Autoimmunity in the Society; www.asset.healthcare ) is a public/private consortium that was established to contribute to research around screening for type 1 diabetes and particularly to how AI can drive the implementation of a precision medicine approach to disease prevention. ASSET will additionally focus on issues pertaining to operational implementation of screening. The authors of this article, researchers and clinicians active in the field of type 1 diabetes, met in an open forum to independently debate key issues around screening for type 1 diabetes and to advise ASSET. The potential use of AI in the analysis of longitudinal data from observational cohort studies to inform the design of improved, more individualised screening programmes was also discussed. A key issue was whether AI would allow the research community and industry to capitalise on large publicly available data repositories to design screening programmes that allow the early detection of individuals at high risk and enable clinical evaluation of preventive therapies. Overall, AI has the potential to revolutionise type 1 diabetes screening, in particular to help identify individuals who are at increased risk of disease and aid in the design of appropriate follow-up plans. We hope that this initiative will stimulate further research on this very timely topic.

Perivascular Macrophages Regulate Blood Flow Following Tissue Damage.

[Figure: see text].

Identification of proliferative and mature ß-cells in the islets of Langerhans.

Insulin-dependent diabetes is a complex multifactorial disorder characterized by loss or dysfunction of ß-cells. Pancreatic ß-cells differ in size, glucose responsiveness, insulin secretion and precursor cell potential; understanding the mechanisms that underlie this functional heterogeneity might make it possible to develop new regenerative approaches. Here we show that Fltp (also known as Flattop and Cfap126), a Wnt/planar cell polarity (PCP) effector and reporter gene acts as a marker gene that subdivides endocrine cells into two subpopulations and distinguishes proliferation-competent from mature ß-cells with distinct molecular, physiological and ultrastructural features. Genetic lineage tracing revealed that endocrine subpopulations from Fltp-negative and -positive lineages react differently to physiological and pathological changes. The expression of Fltp increases when endocrine cells cluster together to form polarized and mature 3D islet mini-organs. We show that 3D architecture and Wnt/PCP ligands are sufficient to trigger ß-cell maturation. By contrast, the Wnt/PCP effector Fltp is not necessary for ß-cell development, proliferation or maturation. We conclude that 3D architecture and Wnt/PCP signalling underlie functional ß-cell heterogeneity and induce ß-cell maturation. The identification of Fltp as a marker for endocrine subpopulations sheds light on the molecular underpinnings of islet cell heterogeneity and plasticity and might enable targeting of endocrine subpopulations for the regeneration of functional ß-cell mass in diabetic patients.

Characterisation of enterovirus RNA detected in the pancreas and other specimens of live patients with newly diagnosed type 1 diabetes in the DiViD study.

AIMS/HYPOTHESIS: The Diabetes Virus Detection (DiViD) study is the first study to laparoscopically collect pancreatic tissue and purified pancreatic islets together with duodenal mucosa, serum, peripheral blood mononuclear cells (PBMCs) and stools from six live adult patients (age 24-35 years) with newly diagnosed type 1 diabetes. The presence of enterovirus (EV) in the pancreatic islets of these patients has previously been reported. METHODS: In the present study we used reverse transcription quantitative real-time PCR (RT-qPCR) and sequencing to characterise EV genomes present in different tissues to understand the nature of infection in these individuals. RESULTS: All six patients were found to be EV-positive by RT-qPCR in at least one of the tested sample types. Four patients were EV-positive in purified islet culture medium, three in PBMCs, one in duodenal biopsy and two in stool, while serum was EV-negative in all individuals. Sequencing the 5' untranslated region of these EVs suggested that all but one belonged to enterovirus B species. One patient was EV-positive in all these sample types except for serum. Sequence analysis revealed that the virus strain present in the isolated islets of this patient was different from the strain found in other sample types. None of the islet-resident viruses could be isolated using EV-permissive cell lines. CONCLUSIONS/INTERPRETATION: EV RNA can be frequently detected in various tissues of patients with type 1 diabetes. At least in some patients, the EV strain in the pancreatic islets may represent a slowly replicating persisting virus.

Phase 3 trial of human islet-after-kidney transplantation in type 1 diabetes.

Allogeneic islet transplant offers a minimally invasive option for ß cell replacement in the treatment of type 1 diabetes (T1D). The CIT consortium trial of purified human pancreatic islets (PHPI) in patients with T1D after kidney transplant (CIT06), a National Institutes of Health-sponsored phase 3, prospective, open-label, single-arm pivotal trial of PHPI, was conducted in 24 patients with impaired awareness of hypoglycemia while receiving intensive insulin therapy. PHPI were manufactured using standardized processes. PHPI transplantation was effective with 62.5% of patients achieving the primary endpoint of freedom from severe hypoglycemic events and HbA1c  ≤ 6.5% or reduced by ≥ 1 percentage point at 1 year posttransplant. Median HbA1c declined from 8.1% before to 6.0% at 1 year and 6.3% at 2 and 3 years following transplant (P < .001 for all vs baseline), with related improvements in hypoglycemia awareness and glucose variability. The improved metabolic control was associated with better health-related and diabetes-related quality of life. The procedure was safe and kidney allograft function remained stable after 3 years. These results add to evidence establishing allogeneic islet transplant as a safe and effective treatment for patients with T1D and unstable glucose control despite intensive insulin treatment, supporting the indication for PHPI in the post-renal transplant setting.

Autologous regulatory T cells in clinical intraportal allogenic pancreatic islet transplantation.

Allogeneic islet transplantation in type 1 diabetes requires lifelong immunosuppression to prevent graft rejection. This medication can cause adverse effects and increases the susceptibility for infections and malignancies. Adoptive therapies with regulatory T cells (Tregs) have shown promise in reducing the need for immunosuppression in human transplantation settings but have previously not been evaluated in islet transplantation. In this study, five patients with type 1 diabetes undergoing intraportal allogeneic islet transplantation were co-infused with polyclonal autologous Tregs under a standard immunosuppressive regimen. Patients underwent leaukapheresis from which Tregs were purified by magnetic-activated cell sorting (MACS) and cryopreserved until transplantation. Dose ranges of 0.14-1.27 × 106 T cells per kilo bodyweight were transplanted. No negative effects were seen related to the Treg infusion, regardless of cell dose. Only minor complications related to the immunosuppressive drugs were reported. This first-in-man study of autologous Treg infusion in allogenic pancreatic islet transplantation shows that the treatment is safe and feasible. Based on these results, future efficacy studies will be developed under the label of advanced therapeutic medical products (ATMP), using modified or expanded Tregs with the aim of minimizing the need for chronic immunosuppressive medication in islet transplantation.

US food and drug administration (FDA) panel endorses islet cell treatment for type 1 diabetes: A pyrrhic victory?

Allogeneic islet transplantation is a standard of care treatment for patients with labile type 1 diabetes in many countries around the world, including Japan, the United Kingdom, Australia, much of continental Europe, and parts of Canada. The United States is now endorsing islet cell treatment for type 1 diabetes, but the FDA has chosen to consider islets as a biologic that requires licensure, making the universal implementation of the procedure in the clinic very challenging and opening the manufacture of islet grafts to private companies. The commercialization of human tissues raises significant legal and ethical issues and ironically leads to a situation where treatments developed as a result of the scientific and economic efforts of academia over several decades become exploited exclusively by for-profit entities.

Inhibition of the prostaglandin D2-GPR44/DP2 axis improves human islet survival and function.

AIMS/HYPOTHESIS: Inflammatory signals and increased prostaglandin synthesis play a role during the development of diabetes. The prostaglandin D2 (PGD2) receptor, GPR44/DP2, is highly expressed in human islets and activation of the pathway results in impaired insulin secretion. The role of GPR44 activation on islet function and survival rate during chronic hyperglycaemic conditions is not known. In this study, we investigate GPR44 inhibition by using a selective GPR44 antagonist (AZ8154) in human islets both in vitro and in vivo in diabetic mice transplanted with human islets. METHODS: Human islets were exposed to PGD2 or proinflammatory cytokines in vitro to investigate the effect of GPR44 inhibition on islet survival rate. In addition, the molecular mechanisms of GPR44 inhibition were investigated in human islets exposed to high concentrations of glucose (HG) and to IL-1ß. For the in vivo part of the study, human islets were transplanted under the kidney capsule of immunodeficient diabetic mice and treated with 6, 60 or 100 mg/kg per day of a GPR44 antagonist starting from the transplantation day until day 4 (short-term study) or day 17 (long-term study) post transplantation. IVGTT was performed on mice at day 10 and day 15 post transplantation. After termination of the study, metabolic variables, circulating human proinflammatory cytokines, and hepatocyte growth factor (HGF) were analysed in the grafted human islets. RESULTS: PGD2 or proinflammatory cytokines induced apoptosis in human islets whereas GPR44 inhibition reversed this effect. GPR44 inhibition antagonised the reduction in glucose-stimulated insulin secretion induced by HG and IL-1ß in human islets. This was accompanied by activation of the Akt-glycogen synthase kinase 3ß signalling pathway together with phosphorylation and inactivation of forkhead box O-1and upregulation of pancreatic and duodenal homeobox-1 and HGF. Administration of the GPR44 antagonist for up to 17 days to diabetic mice transplanted with a marginal number of human islets resulted in reduced fasting blood glucose and lower glucose excursions during IVGTT. Improved glucose regulation was supported by increased human C-peptide levels compared with the vehicle group at day 4 and throughout the treatment period. GPR44 inhibition reduced plasma levels of TNF-α and growth-regulated oncogene-α/chemokine (C-X-C motif) ligand 1 and increased the levels of HGF in human islets. CONCLUSIONS/INTERPRETATION: Inhibition of GPR44 in human islets has the potential to improve islet function and survival rate under inflammatory and hyperglycaemic stress. This may have implications for better survival rate of islets following transplantation.

No Evidence for Presence of Mucosal-Associated Invariant T Cells in the Insulitic Lesions in Patients Recently Diagnosed with Type 1 Diabetes.

Mucosal-associated invariant T (MAIT) cells are innate T cells that recognize bacteria-infected cells and are thought to play a role in autoimmune diseases. Translocation of duodenal bacteria and viruses to the pancreas through the pancreatic duct has been hypothesized to initiate an innate inflammatory response that could contribute to the development of type 1 diabetes, a process that could involve MAIT cells. In this study, we used immunohistochemistry and quantitative PCR to search for evidence of MAIT cells in the insulitic lesions in the pancreas of human patients recently diagnosed with type 1 diabetes. Only a few scattered MAIT cells were found within the exocrine parenchyma in all pancreatic samples, but no MAIT cells were found in association to the islets. Also, only low gene expression levels of the MAIT T-cell receptor Vα7.2-Jα33 were found in the pancreas of patients with type 1 diabetes, in similar levels as that in nondiabetic organ donors used as control. The absence of MAIT cells shown in insulitic lesions in humans questions the direct cytotoxic role of these cells in ß-cell destruction.

Proton MR spectroscopy of human pancreas allografts.

OBJECTIVE: To estimate pancreas graft relaxation times and concentrations of total fat, and the intracellular lipids of non-adipose pancreatic cells (NAPC) using proton (1H) magnetic resonance spectroscopy (MRS) during cold preservation. MATERIALS AND METHODS: Grafts from 11 human donors were investigated. Each pancreas was perfused in situ with histidine-tryptophan-ketoglutarate (HTK) or with University of Wisconsin solution and placed into a transport container. Temperature of the grafts was maintained at 4 ± 2 °C during transport to our hospital and MR scanning. A 1.5 T clinical scanner was used for the measurements. Single-voxel PRESS spectra were acquired using transmit-receiver head coil. RESULTS: Relaxation times were measured for lipid (-CH2-)n (T1, 287 ± 60 ms; T2, 27 ± 4 ms), and tissue water (T1, 670 ± 69 ms; T2, 77 ± 17 ms). Average total fat, and intracellular lipids of NAPC concentrations were 79.2 ± 100.8 (range 2.4-304.4), and 2.9 ± 1.2 mmol/kg ww, respectively. CONCLUSION: We have shown that 1H-MRS is a useful tool for the estimation of pancreas graft lipid concentrations. Total pancreatic fat and especially content of intracellular lipids of NAPC are valuable measures for inspection of graft quality prior to transplantation or islet of Langerhans isolation.

Detection and quantification of beta cells by PET imaging: why clinical implementation has never been closer.

In this issue of Diabetologia, Alavi and Werner ( https://doi.org/10.1007/s00125-018-4676-1 ) criticise the attempts to use positron emission tomography (PET) for in vivo imaging of pancreatic beta cells, which they consider as 'futile'. In support of this strong statement, they point out the limitations of PET imaging, which they believe render beta cell mass impossible to estimate using this method. In our view, the Alavi and Werner presentation of the technical limitations of PET imaging does not reflect the current state of the art, which leads them to questionable conclusions towards the feasibility of beta cell imaging using this approach. Here, we put forward arguments in favour of continuing the development of innovative technologies enabling in vivo imaging of pancreatic beta cells and concisely present the current state of the art regarding putative technical limitations of PET imaging. Indeed, far from being a 'futile' effort, we demonstrate that beta cell imaging is now closer than ever to becoming a long-awaited clinical reality.

Transplantation of macroencapsulated human islets within the bioartificial pancreas ßAir to patients with type 1 diabetes mellitus.

Macroencapsulation devices provide the dual possibility of immunoprotecting transplanted cells while also being retrievable, the latter bearing importance for safety in future trials with stem cell-derived cells. However, macroencapsulation entails a problem with oxygen supply to the encapsulated cells. The ßAir device solves this with an incorporated refillable oxygen tank. This phase 1 study evaluated the safety and efficacy of implanting the ßAir device containing allogeneic human pancreatic islets into patients with type 1 diabetes. Four patients were transplanted with 1-2 ßAir devices, each containing 155 000-180 000 islet equivalents (ie, 1800-4600 islet equivalents per kg body weight), and monitored for 3-6 months, followed by the recovery of devices. Implantation of the ßAir device was safe and successfully prevented immunization and rejection of the transplanted tissue. However, although beta cells survived in the device, only minute levels of circulating C-peptide were observed with no impact on metabolic control. Fibrotic tissue with immune cells was formed in capsule surroundings. Recovered devices displayed a blunted glucose-stimulated insulin response, and amyloid formation in the endocrine tissue. We conclude that the ßAir device is safe and can support survival of allogeneic islets for several months, although the function of the transplanted cells was limited (Clinicaltrials.gov: NCT02064309).

Demonstration of Tissue Resident Memory CD8 T Cells in Insulitic Lesions in Adult Patients with Recent-Onset Type 1 Diabetes.

Subtypes of CD8+ T cells in insulitic lesions in biopsy specimens from six subjects with recent-onset type 1 diabetes (T1D) and six nondiabetic matched controls were analyzed using simultaneous multicolor immunofluorescence. Also, insulitic islets based on accumulation of CD3+ T cells were microdissected with laser-capture microscopy, and gene transcripts associated with inflammation and autoimmunity were analyzed. We found a substantial proportion, 43%, of the CD8+ T cells in the insulitic lesions to display a tissue resident memory T cell (TRM) (CD8+CD69+CD103+) phenotype in T1D subjects. Most TRM cells were located in the insulitic lesion in the endocrine-exocrine interface. TRM cells were also sporadically found in islets of control subjects. Moreover, gene expression analysis showed a lack of active transcription of genes associated with acute inflammatory or cytotoxic T-cell responses. We present evidence that a substantial proportion of T cells in insulitic lesions of recent-onset T1D patients are TRM cells and not classic cytotoxic CD8+ T cells. Our findings highlight the need for further analysis of the T cells involved in insulitis to elucidate their role in the etiology of T1D.

Aetiology of type 1 diabetes: Physiological growth in children affects disease progression.

The prevailing view is that type 1 diabetes (T1D) develops as a consequence of a severe decline in ß-cell mass resulting from T-cell-mediated autoimmunity; however, progression from islet autoantibody seroconversion to overt diabetes and finally to total loss of C-peptide production occurs in most affected individuals only slowly over many years or even decades. This slow disease progression should be viewed in relation to the total ß-cell mass of only 0.2 to 1.5 g in adults without diabetes. Focal lesions of acute pancreatitis with accumulation of leukocytes, often located around the ducts, are frequently observed in people with recent-onset T1D, and most patients display extensive periductal fibrosis, the end stage of inflammation. An injurious inflammatory adverse event, occurring within the periductal area, may have negative implications for islet neogenesis, dependent on stem cells residing within or adjacent to the ductal epithelium. This could in part prevent the 30-fold increase in ß-cell mass that would normally occur during the first 20 years of life. This increase occurs in order to maintain glucose metabolism during the physiological increases in insulin production that are required to balance the 20-fold increase in body weight during childhood and increased insulin resistance during puberty. Failure to expand ß-cell mass during childhood would lead to clinically overt T1D and could help to explain the apparently more aggressive form of T1D occurring in growing children when compared with that observed in affected adults.

Insulitis in human diabetes: a histological evaluation of donor pancreases.

AIMS/HYPOTHESIS: According to the consensus criteria developed for type 1 diabetes, an individual can be diagnosed with insulitis when ≥ 15 CD45+ cells are found within the parenchyma or in the islet-exocrine interface in ≥ 3 islets. The aim of this study was to determine the frequency of individuals with type 2 diabetes fulfilling these criteria with reference to non-diabetic and type 1 diabetic individuals. METHODS: Insulitis was determined by examining CD45+ cells in the pancreases of 50, 13 and 44 organ donors with type 2 diabetes, type 1 diabetes and no diabetes, respectively. CD3+ cells (T cells) infiltrating the islets were evaluated in insulitic donors. In insulitic donors with type 2 diabetes, the pancreases were characterised according to the presence of CD68 (macrophages), myeloperoxidase (MPO; neutrophils), CD3, CD20 (B cells) and HLA class I hyperstained islets. In all type 2 diabetic donors, potential correlations of insulitis with dynamic glucose-stimulated insulin secretion in vitro or age, BMI, HbA1c or autoantibody positivity were examined. RESULTS: Overall, 28% of the type 2 diabetic donors fulfilled the consensus criteria for insulitis developed for type 1 diabetes. Of the type 1 diabetic donors, 31% fulfilled the criteria. None of the non-diabetic donors met the criteria. Only type 1 diabetic donors had ≥ 15 CD3+ cells in ≥ 3 islets. Type 2 diabetic donors with insulitis also had a substantial number of CD45+ cells in the exocrine parenchyma. Macrophages constituted the largest fraction of CD45+ cells, followed by neutrophils and T cells. Of type 2 diabetic pancreases with insulitis, 36% contained islets that hyperstained for HLA class I. Isolated islets from type 2 diabetic donors secreted less insulin than controls, although with preserved dynamics. Insulitis in the type 2 diabetic donors did not correlate with glucose-stimulated insulin secretion, the presence of autoantibodies, BMI or HbA1c. CONCLUSIONS/INTERPRETATION: The current definition of insulitis cannot be used to distinguish pancreases retrieved from individuals with type 1 diabetes from those with type 2 diabetes. On the basis of our findings, we propose a revised definition of insulitis, with a positive diagnosis when ≥ 15 CD3+ cells, not CD45+ cells, are found in ≥ 3 islets.

Cost and clinical outcome of islet transplantation in Norway 2010-2015.

Islet transplantation is a minimally invasive ß-cell replacement strategy. Islet transplantation is a reimbursed treatment in Norway. Here, we summarize the cost and clinical outcome of 31 islet transplantations performed at Oslo University Hospital (OUS) from January 2010 to June 2015. Patients were retrospectively divided into three groups. Thirteen patients received either one or two islet transplantation alone (ITA), while five patients received islet transplantation after previous solid organ transplantation. For the group receiving 2 ITA, Kaplan-Meier estimates show an insulin independence of 20% more than 4 years after their last transplantation. An estimated 70% maintain at least partial graft function, defined as fasting C-peptide >0.1 nmol L-1 , and 47% maintain a HbA1c below 6.5% or 2 percent points lower than before ITA. For all groups combined, we estimate that 44% of the patients have a 50% reduction in insulin requirement 4 years after the initial islet transplantation. The average cost for an islet transplantation procedure was 347 297±60 588 NOK, or 35 424±6182 EUR, of which isolation expenses represent 34%. We hereby add to the common pool of growing experience with islet transplantation and also describe the cost of the treatment at our center.

Pancreatic perfusion and subsequent response to glucose in healthy individuals and patients with type 1 diabetes.

AIMS/HYPOTHESIS: The aim of this study was to investigate pancreatic perfusion and its response to a glucose load in patients with type 1 diabetes mellitus compared with non-diabetic ('healthy') individuals. METHODS: Eight individuals with longstanding type 1 diabetes and ten sex-, age- and BMI-matched healthy controls underwent dynamic positron emission tomography scanning with (15)O-labelled water before and after intravenous administration of glucose. Perfusion in the pancreas was measured. Portal and arterial hepatic perfusion were recorded as references. RESULTS: Under fasting conditions, total pancreatic perfusion was on average 23% lower in the individuals with diabetes compared with healthy individuals. Glucose increased total pancreatic and portal hepatic blood perfusion in healthy individuals by 48% and 38%, respectively. In individuals with diabetes there was no significant increase in either total pancreatic or portal hepatic perfusion. CONCLUSIONS/INTERPRETATION: Individuals with type 1 diabetes have reduced basal pancreatic perfusion and a severely impaired pancreatic and splanchnic perfusion response to intravenous glucose stimulation.

Insulitis and characterisation of infiltrating T cells in surgical pancreatic tail resections from patients at onset of type 1 diabetes.

AIMS/HYPOTHESIS: It is thought that T cells play a major role in the immune-mediated destruction of beta cells in type 1 diabetes, causing inflammation of the islets of Langerhans (insulitis). The significance of insulitis at the onset of type 1 diabetes is debated, and the role of the T cells poorly understood. METHODS: In the Diabetes Virus Detection (DiViD) study, pancreatic tissue from six living patients with recent-onset type 1 diabetes was collected. The insulitis was characterised quantitatively by counting CD3(+) T cells, and qualitatively by transcriptome analysis targeting 84 T and B lymphocyte genes of laser-captured microdissected islets. The findings were compared with gene expression in T cells collected from kidney biopsies from allografts with ongoing cellular rejection. Cytokine and chemokine release from isolated islets was characterised and compared with that from islets from non-diabetic organ donors. RESULTS: All six patients fulfilled the criteria for insulitis (5-58% of the insulin-containing islets in the six patients had ≥ 15 T cells/islet). Of all the islets, 36% contained insulin, with several resembling completely normal islets. The majority (61-83%) of T cells were found as peri-insulitis rather than within the islet parenchyma. The expression pattern of T cell genes was found to be markedly different in islets compared with the rejected kidneys. The islet-infiltrating T cells showed only background levels of cytokine/chemokine release in vitro. CONCLUSIONS/INTERPRETATION: Insulitis and a significant reserve reservoir for insulin production were present in all six cases of recent-onset type 1 diabetes. Furthermore, the expression patterns and levels of cytokines argue for a different role of the T cells in type 1 diabetes when compared with allograft rejection.