Expression of nephrin by human pancreatic islet endothelial cells

AIMS/HYPOTHESIS

The islet microcirculation has morphological characteristics resembling those of renal glomeruli. Transcription of the nephrin gene, a highly specific barrier protein of the slit diaphragm of podocyte foot processes, has been reported in the pancreas, although its cellular localisation and function remain to be defined. In this study, we purified and characterised microvascular endothelial cells (MECs) isolated from human islets and investigated the expression and distribution of nephrin on these cells.

METHODS

Human islet MECs were extracted and purified using anti-CD105-coated immunomagnetic beads and their endothelial characteristics were confirmed by expression of classical endothelial markers and basal high-level expression of intercellular adhesion molecule-1 and TNF-alpha-inducible vascular cell adhesion molecule-1. Nephrin expression was assessed by immunofluorescence, flow cytometric analysis and western blotting on cell lysates, as well as by RT-PCR.

RESULTS

Immunofluorescence studies detected nephrin in a fine, punctate, diffuse pattern on cultured islet MECs, and also in human pancreatic islet sections. In both cases nephrin colocalised with endothelial markers. TNF-alpha treatment induced a marked reduction and redistribution of the protein in one or multiple aggregates. Nephrin expression was confirmed by flow cytometry, western blotting and RT-PCR studies. In contrast, nephrin could not be detected at the protein or mRNA level in human macro- and microvascular cells from other sites.

CONCLUSIONS/INTERPRETATION

Nephrin is expressed at protein and mRNA levels in islet microendothelium, supporting the hypothesis that islet MECs exhibit distinctive morphological characteristics that indicate functional specialisation of potential pathophysiological importance.

Autoantibodies to autonomic nerves associated with cardiac and peripheral autonomic neuropathy

OBJECTIVE

This study examines whether autonomic nerve autoantibodies (ANabs) are associated with development of autonomic neuropathy using a prospective study design.

RESEARCH DESIGN AND METHODS

A group of type 1 diabetic patients were followed prospectively with regard to autonomic nerve function on four occasions. At the third examination, 41 patients were tested for ANabs (complement-fixing autoantibodies to the sympathetic ganglion, vagus nerve, and adrenal medulla), and the results were related to cardiac autonomic nerve function (heart rate variation during deep breathing [expiration/inspiration ratio] and heart-rate reaction to tilt [acceleration and brake index]) and to peripheral sympathetic nerve function (vasoconstriction after indirect cooling [vasoconstriction index]).

RESULTS

ANabs were detected in 23 of 41 (56%) patients at the third examination. Compared with patients without ANabs (ANabs-), patients with ANabs (ANabs+) showed significantly higher frequencies of at least one abnormal cardiac autonomic nerve function test at the third examination (17 of 23 [74%] vs. 7 of 18 [39%]; P = 0.03) and fourth examination (15 of 21 [71%] vs. 4 of 16 [25%]; P < 0.01). In contrast, there was no similar difference at the first or second examination. The relative risk for ANabs(+) patients to develop cardiac autonomic neuropathy at follow-up was 7.5 (95% CI 1.72-32.80). The vasoconstriction index was more abnormal in ANabs+ than in ANabs- patients at the fourth examination (median 1.40 [interquartile range 1.58] vs. 0.35 [2.05]; P = 0.01).

CONCLUSIONS

ANabs were associated with future development of cardiac and peripheral autonomic neuropathy in diabetic patients, implying an etiological relationship between nervous tissue autoimmunity and these diabetes complications.

Detection of autoreactive T cells in type 1 diabetes using coded autoantigens and an immunoglobulin-free cytokine ELISPOT assay: report from the fourth immunology of diabetes society T cell workshop

The "gold standard" for evaluation of immunoassays is blinded testing, using coded samples and antigens. Although assays for autoreactive T cells are no exception to this rule, it is nonetheless rarely applied in this context. To facilitate such investigations, we coded a panel of 10 peptides representing T cell epitopes reported to be of relevance to islet autoimmunity. These were deployed in a novel cytokine ELISPOT assay, in which the use of immunoglobulin-free medium reduces background reactivity and thus potentially enhances the specificity and sensitivity of detection of autoreactive T cells. Significant IFN-gamma production against GAD65 (554-575), insulin (B9-23), and IA-2 (709-736) peptides were observed in type 1 diabetic patients, whereas no significant changes from background were detected in healthy controls. These results confirm the utility of the blinded performance of T cell assays as the most robust platform for assessing technologies to T cell autoreactivity.

Defective suppressor function in CD4(+)CD25(+) T-cells from patients with type 1 diabetes

Type 1 diabetes is a T-cell-mediated disease that is associated with loss of immunological tolerance to self-antigens. The mechanisms involved in maintenance of peripheral tolerance include a specialized subset of regulatory T-cells (Treg) within the CD4(+)CD25(+) T-cell population, but the function and phenotype of these cells in type 1 diabetes have not been investigated. We hypothesized that a deficiency in the CD4(+)CD25(+) Treg population or its function could contribute to the lack of self-tolerance evident in patients with type 1 diabetes. We show that although levels of CD4(+)CD25(+) T-cells are normal in patients with recent-onset adult type 1 diabetes, the ability of the Tregs in this population to suppress T-cell proliferation during in vitro cocultures is markedly reduced compared with control subjects (P = 0.007). Moreover, in patients with type 1 diabetes, these cocultures display a more proinflammatory phenotype, with increased secretion of interferon-gamma (P = 0.005) and decreased interleukin-10 production (P = 0.03). These deficiencies may reflect a disturbance in the balance of the CD4(+)CD25(+) population, because in patients with type 1 diabetes, a higher proportion of these cells coexpress the early activation marker CD69 (P = 0.007) and intracellular CTLA-4 (P = 0.01). These data demonstrate deficiency in function of the CD4(+)CD25(+) Treg population that may influence the pathogenesis of type 1 diabetes.

Identification of a naturally processed cytotoxic CD8 T-cell epitope of coxsackievirus B4, presented by HLA-A2.1 and located in the PEVKEK region of the P2C nonstructural protein

The adaptive immune system generates CD8 cytotoxic T lymphocytes (CTLs) as a major component of the protective response against viruses. Knowledge regarding the nature of the peptide sequences presented by HLA class I molecules and recognized by CTLs is thus important for understanding host-pathogen interactions. In this study, we focused on identification of a CTL epitope generated from coxsackievirus B4 (CVB4), a member of the enterovirus group responsible for several inflammatory diseases in humans and often implicated in the triggering and/or acceleration of the autoimmune disease type 1 diabetes. We identified a 9-mer peptide epitope that can be generated from the P2C nonstructural protein of CVB4 (P2C(1137-1145)) and from whole virus by antigen-presenting cells and presented by HLA-A2.1. This epitope is recognized by effector memory (gamma interferon [IFN-gamma]-producing) CD8 T cells in the peripheral blood at a frequency of responders that suggests that it is a major focus of the anti-CVB4 response. Short-term CD8 T-cell lines generated against P2C(1137-1145) are cytotoxic against peptide-loaded target cells. Of particular interest, the epitope lies within a region of viral homology with the diabetes-related autoantigen, glutamic acid decarboxylase-65 (GAD(65)). However, P2C(1137-1145)-specific cytotoxic T lymphocyte (CTL) lines were not activated to produce IFN-gamma by the GAD(65) peptide homologue and did not show cytotoxic activity in the presence of appropriately labeled targets. These results describe the first CD8 T-cell epitope of CVB4 that will prove useful in the study of CVB4-associated disease.

Enhancing the Sensitivity of Assays to Detect T Cell Reactivity: The Effect of Cell Separation and Cryopreservation Media

The identification of sensitive assay formats capable of distinguishing islet autoreactive T cells directly ex vivo in blood is a major goal in type 1 diabetes research. Whereas much effort has been made to identify suitable assay formats, relatively little attention has been paid to optimizing the quality of cell preparations used. To address this issue we investigated the role of two key variables in the preparation of peripheral blood mononuclear cells (PBMCs): the separation media used in density gradient centrifugation and the method of cryopreservation. PBMCs were prepared from a single individual using different protocols and tested for responses to suboptimal concentrations of tetanus toxoid, representing a low frequency recall response. Significant differences were observed in T cell responses dependent upon the selection of the separation media and cryopreservation methods used, indicating that relatively small differences in preparation of PBMCs can have measurable effects on assay sensitivity.

Possession of human leucocyte antigen DQ6 alleles and the rate of CD4 T-cell decline in human immunodeficiency virus-1 infection

Polymorphism amongst the human leucocyte antigen (HLA) class II genes could influence antigen presentation and the ability to control human immunodeficiency virus (HIV)-1 by modulating the virus specific CD4 immune response. To examine the effect of such polymorphisms on disease progression, we studied a cohort of 46 HIV-1 infected long-term non-progressors (LTNPs), 87 intermediate progressors (IPs) and 26 rapid progressors. Kaplan-Meier survival analysis of all patients in the cohort on time to a CD4 count less than 350 cells/ micro l, showed a trend for a slower rate of CD4 decline in patients with, compared to those without, the DRB1*15-DQB1*06 haplotype (hazard ratio (HR) 0.69, 95% CI 0.46-1.01, P = 0.06). A similar effect was not observed with the DRB1*13-DQB1*06 haplotype (HR 1.18, 95% CI 0.75-1.88, P = 0.46), but was observed when DQB1*06 alleles were considered irrespective of their DR association (HR 0.74, 95% CI 0.52-1.05, P = 0.06). Major HLA-DQ6 alleles encode aspartate (Asp) at position 57 on the DQbeta chain, a phenotype associated with protection from other immune disorders. We therefore examined the frequency of all DQbeta57 Asp+ alleles, but could not detect a significant effect on the rate of CD4 decline. To examine whether the genotype associated with slower CD4 decline was over-represented in patients with a slow rate of disease progression, we conducted a categorical analysis of a subset of patients with an extended follow-up of 14+years. We found a higher proportion of LTNPs at 14+ years possessed the DRB1*15-DQB1*06 haplotype compared to IPs at 14+ years (38.46 versus 18.18%), though this difference did not reach statistical significance. When DQB1*06 alleles irrespective of their DR association were considered, the protective effect was greater (76.9% LTNPs versus 18.18% IPs, P = 0.04). Our results highlight the potential protective effect of HLA DQB1*06 alleles on the course of HIV disease.

HLA class II polymorphisms determine responses to bacterial superantigens

The excessive immunological response triggered by microbial superantigens has been implicated in the etiology of a wide range of human diseases but has been most clearly defined for the staphylococcal and streptococcal toxic shock syndromes. Because MHC class II presentation of superantigens to T cells is not MHC-restricted, the possibility that HLA polymorphisms could influence superantigenicity, and thus clinical susceptibility to the toxicity of individual superantigens, has received little attention. In this study, we demonstrate that binding of streptococcal and staphylococcal superantigens to HLA class II is influenced by allelic differences in class II. For the superantigen streptococcal pyrogenic exotoxin A, class II binding is dependent on DQ alpha-chain polymorphisms such that HLA-DQA1*01 alpha-chains show greater binding than DQA1*03/05 alpha-chains. The functional implications of differential binding on T cell activation were investigated in various experimental systems using human T cells and murine Vbeta8.2 transgenic cells as responders. These studies showed quantitative and qualitative differences resulting from differential HLA-DQ binding. We observed changes in T cell proliferation and cytokine production, and in the Vbeta specific changes in T cell repertoire that have hitherto been regarded as a defining feature of an individual superantigen. Our observations reveal a mechanism for the different outcomes seen following infection by toxigenic bacteria.

Autoreactive T cell responses show proinflammatory polarization in diabetes but a regulatory phenotype in health

According to the quality of response they mediate, autoreactive T cells recognizing islet beta cell peptides could represent both disease effectors in the development of type 1 diabetes (T1DM) and directors of tolerance in nondiabetic individuals or those undergoing preventative immunotherapy. A combination of the rarity of these cells, inadequate technology, and poorly defined epitopes, however, has hampered examination of this paradigm. We have identified a panel of naturally processed islet epitopes by direct elution from APCs bearing HLA-DR4. Employing these epitopes in a sensitive, novel cytokine enzyme-linked immunosorbent spot assay, we show that the quality of autoreactive T cells in patients with T1DM exhibits extreme polarization toward a proinflammatory Th1 phenotype. Furthermore, we demonstrate that rather than being unresponsive, the majority of nondiabetic, HLA-matched control subjects also manifest a response against islet peptides, but one that shows extreme T regulatory cell (Treg, IL-10-secreting) bias. We conclude that development of T1DM depends on the balance of autoreactive Th1 and Treg cells, which may be open to favorable manipulation by immune intervention.

High levels of type 2 cytokine-producing cells in chronic fatigue syndrome

The aetiology of chronic fatigue syndrome (CFS) is not known. However, it has been suggested that CFS may be associated with underlying immune activation resulting in a Th2-type response. We measured intracellular production of interferon (IFN)-gamma and interleukin (IL)-2; type 1 cytokines), IL-4 (type 2) and IL-10 (regulatory) by both polyclonally stimulated and non-stimulated CD4 and CD8 lymphocytes from patients with CFS and control subjects by flow cytometry. After polyclonal activation we found evidence of a significant bias towards Th2- and Tc2-type immune responses in CFS compared to controls. In contrast, levels of IFN-gamma, IL-2 and IL-10-producing cells were similar in both study groups. Non-stimulated cultures revealed significantly higher levels of T cells producing IFN-gamma or IL-4 in CFS patients. Concluding, we show evidence for an effector memory cell bias towards type 2 responsiveness in patients with CFS, as well as ongoing type 0 immune activation in unstimulated cultures of peripheral blood cells.

The development of new density gradient media for purifying human islets and islet-quality assessments

Successful islet transplantation is dependent on the quality and quantity of islets infused. Islets are purified on density gradients, but procedures currently used have limited capacity for pancreatic digests, islet yield, and viability. We aimed to improve islet purification with a modified gradient medium. Biocoll was diluted in University of Wisconsin solution to create linear density gradients of 1.065 to 1.095 g/mL. Properties of islets purified from 22 human pancreas digests with modified medium were compared with 15 preparations using standard medium. The modification increased the capacity of gradients for pancreatic digests from 20 to 60 mL, islet yield increased from 218,000 to 435,318 per isolation, and viability increased from 65.4% to 92.1%. Islet fractions contained greater than 95% of recovered insulin. Islets showed good physiologic responses to secretagogues and restored normoglycemia in streptozotocin-induced diabetic severe combined immunodeficiency disease mice. The new medium enhances yield, purity, and viability of human islet preparations for clinical islet transplantation.

Cellular Immune Activation in Gulf War Veterans

The etiology and pathology of illnesses related to the first Persian Gulf War are unclear. Among the constellation of symptoms noted in sick veterans, some, such as skin rashes, musculoskeletal pains, and neuropsychiatric problems, have been proposed to reflect an underlying immune dysfunction. In this study we explored the hypothesis that sickness following deployment to the Gulf in 1991 is associated with altered immune function, and we examine possible associated exposures. In particular, we focused on peripheral blood Th1/Th2 balance by measuring intracellular production of IFN-gamma, IL-2 (Th1), IL-4 (Th2), and IL-10 by CD4 T cells, using a nested case control study design within a large epidemiological survey. We compared symptomatic Gulf War veterans (sGWV) with well GWVs (wGWV), and a second control group of symptomatic veterans who served in Bosnia or were nondeployed military personnel of the same era. We found evidence for an altered immune status in sGWV in comparison to the other study groups. In particular, ongoing Th1-type immune activation was associated with multisymptom illness in GWVs, with sick veterans having significantly elevated levels of IFN-gamma and IL-2 producing CD4+ cells in the absence of in vitro stimulation compared with wGWVs (P = 0.01 and P =0.001). In vitro polyclonal activation revealed significantly elevated levels of IL-10 producing memory CD4 cells in sGWVs (P <0.001), but other cytokines were normal. In terms of possible exposures that might influence immune function, we found a trend for reduced levels of IFN-gamma producing cells after polyclonal activation with increasing numbers of vaccines administered (P <0.05) but no changes in other cytokines. These data show that multisymptom illness in Gulf War veterans is characterized by ongoing Th1-type immune activation and a biased generation of memory cells secreting the suppressor cytokine, IL-10.

Comparison of cytokine ELISpot assay formats for the detection of islet antigen autoreactive T cells

The identification of sensitive assay formats capable of distinguishing islet autoreactive T cells directly ex vivo in blood is a major goal in type 1 diabetes research. Recently, much interest has been shown in the cytokine enzyme linked immunospot assay (CK ELISpot), an assay potentially capable of fulfilling these difficult criteria. To address the utility of this assay in detecting autoreactive T cells, a 'wet' workshop was organized using the same fresh blood sample and coded antigens. Five different laboratories participated, using three distinct CK ELISpot assay formats. Samples from two subjects were pre-tested for responses to sub-optimal concentrations of tetanus toxoid, representing a low frequency recall response, and peptides from diabetes associated autoantigens GAD65, IA-2 and HSP60. All participants measured interferon-gamma production and combinations of interleukins-4, -5, -10 and -13. In the workshop 4 of 5 laboratories detected low frequency recall responses in both subjects and 3 of 5 detected at least one of the autoreactive peptide responses concordant with pre-testing. Significant assay format related differences in sensitivity and signal-to-noise ratio were observed. The results demonstrate the potential for detection of low-level autoreactive T cell responses and identify assay characteristics that will be useful for studies in type 1 diabetes.

Enteroviruses and type 1 diabetes

The development of type 1 diabetes mellitus (T1DM) has been linked to exposure to environmental triggers, with Enteroviruses (EV) historically considered the prime suspects. Early serological studies suggested a link between EV infections and the development of T1DM and, though controversial, have been bolstered by more recent studies using more sensitive techniques such as direct detection of the EV genome by RT-PCR in peripheral blood. In this review, we consider the weight of evidence that EV can be considered a candidate trigger of T1DM, using three major criteria: (1) is EV infection associated with clinical T1DM, (2) can EV trigger the development of autoimmunity and (3) what would explain the putative association?

A systematic review and critical evaluation of the immunology of chronic fatigue syndrome

OBJECTIVE

Immune dysfunction in patients with chronic fatigue syndrome (CFS) has been widely but inconsistently reported. Traditional reviews of the literature have produced a variety of conclusions. We present the results of the first systematic review of the subject.

METHODS

EMBASE, MEDLINE and PSYCHINFO databases were searched, and leading researchers in the field were contacted. Inclusion criteria were applied, and studies were then divided into groups based on the quality of their methodology. Study results were collated and described.

RESULTS

Studies ranged widely in quality. There was an inverse association between study quality and finding low levels of natural killer cells, suggesting that the association may be related to study methodology. On the other hand, reports of abnormalities in T cells and cytokine levels were not related to study quality.

CONCLUSIONS

The conclusions of this systematic review differ from a recent traditional narrative review of the immunology of CFS. No consistent pattern of immunological abnormalities is identified.

Persistent infection of human microvascular endothelial cells by coxsackie B viruses induces increased expression of adhesion molecules

Numerous studies indicate that enteroviruses, such as the Coxsackievirus (CV) group, are linked to autoimmune diseases. Virus tropism and tissue access are modulated by vascular endothelial cells (ECs), mainly at the level of the microvasculature. Data on the permissiveness of ECs to CV are, however, scanty and derived from studies on large vessel ECs. To examine the susceptibility of microvascular ECs to infection of group B CV (CVB), human dermal microvascular ECs (HMEC-1) were infected with three CVB strains, and the immunological phenotype of the infected cells was analyzed. All CVB persistently infected the EC cultures without producing overt cytopathic effects. Infected ECs retained endothelial characteristics. Release of infectious particles in cell supernatants persisted for up to 3 mo of culture. Infection up-regulated expression of the adhesion molecules ICAM-1 and VCAM-1, with the highest values detected during the first 30 days of infection (p < 0.05 vs uninfected HMEC-1). CVB infection increased production of the proinflammatory cytokines, IL-6, IL-8, and TNF-alpha, which may account for the enhanced expression of adhesion molecules. Parallel infection of macrovascular HUVEC had less evident effects on induction of ICAM-1 and did not significantly increase expression of VCAM-1. Moreover, mononuclear cell adhesion to CVB-infected HMEC-1 monolayers was increased, compared with uninfected monolayers. These results provide evidence that small vessel ECs can harbor a persistent viral infection, resulting in quantitative modification of adhesion molecule expression, which may contribute to the selective recruitment of subsets of leukocytes during inflammatory immune responses. Furthermore, our data confirm that the behavior against a viral challenge of ECs in large vessels and microvessels may differ.

Paraoxonase in Persian Gulf War veterans

Serum paraoxonase (PON1) is responsible for the metabolism of organophosphates in serum, and PON1 activity is a major determinant of their toxicity in humans. There have been reports linking lowered PON1 activity to physical symptoms after deployment to the Persian Gulf War (PGW) of 1990 to 1991. Therefore, the object of this study was to determine (1) whether PON1 activity was decreased among symptomatic PGW veterans compared with asymptomatic PGW veterans and (2) to determine whether PGW veterans as a whole had lower PON1 activity compared with other military control groups. This was a case control study nested in occupational cohort study of military personnel. Four groups of military personnel were identified from a large epidemiological study of health effects of deployment to the PGW and Bosnia: (1) symptomatic PGW veterans, n = 115; (2) healthy PGW veterans, n = 95; (3) symptomatic Bosnia peacekeeping veterans, n = 52; and (4) symptomatic nondeployed military controls, n = 85. The main outcome measures were PON1 activity and genotype for PON1-55 and -192. We found significant differences in PON1 activity among these four groups, and although the two Gulf groups did not differ in PON1 activity, those deployed to the Gulf had significantly lower PON1 activity compared with the non-PGW groups (median difference = 70.9; 95% CI: 20.2, 121.5, P = 0.012). These differences were not explained by a range of potential confounders, or differences in PON1 coding region polymorphisms. PON1 activity is reduced in PGW veterans compared with military control groups. The effect is independent of ill health in PGW veterans.

Promiscuous binding of proinsulin peptides to Type 1 diabetes-permissive and -protective HLA class II molecules

AIMS/HYPOTHESIS

Presentation of peptide epitopes derived from beta-cell autoantigens, such as insulin and its precursor molecules, by MHC class II molecules to autoreactive T-cells is believed to play a role in the development of Type 1 diabetes. However, little is known about the interaction between peptides of (prepro)insulin and MHC class II molecules permissive and protective for Type 1 diabetes. In this study therefore, peptides spanning the human preproinsulin sequence were assessed for their binding characteristics to Type 1 diabetes-protective and -permissive HLA molecules.

METHODS

HLA-DR2, -DQ6.2 (Type 1 diabetes-protective) and HLA-DR4, -DQ8 (Type 1 diabetes permissive) molecule binding affinity for overlapping synthetic 20mer peptides spanning human preproinsulin was measured in a direct competition binding assay against a biotinylated indicator peptide.

RESULTS

All HLA molecules tested showed similarity in their binding characteristics across the preproinsulin molecule, with regions of the insulin A-chain showing the highest affinity and C-peptide regions the lowest affinity for all HLA molecules tested. Furthermore, an insulin peptide implicated as a major CD4+ T-cell target in disease pathogenesis (B9-23) had high affinity binding to both protective and permissive HLA molecules but did not represent the highest affinity region of (prepro)insulin identified in either case.

CONCLUSION/INTERPRETATION

The results suggest that peptide binding affinity alone is unlikely to be the major determinant of disease susceptibility in relation to interactions between (prepro)insulin epitopes and HLA molecules. The identification of epitopes derived from beta-cell autoantigens that bind promiscuously to diabetes-permissive HLA molecules could be important in the design of peptide-based immunotherapeutic strategies for the prevention of Type 1 diabetes.

Processing and presentation of the islet autoantigen GAD by vascular endothelial cells promotes transmigration of autoreactive T-cells

Type 1 diabetes is characterized by T-cell infiltration of the islets of Langerhans and abundant HLA class II molecule expression on islet endothelial cells (ECs). The specificity of infiltrating T-cells for islet autoantigens has been amply demonstrated in animal models, and is implicit in human diabetes, but the processes regulating endothelial transmigration of islet autoantigen-specific T-cells into islets are not known. We examined the ability of ECs expressing HLA class II molecules to process and present the islet autoantigen GAD65 and examined the effects of presentation on transmigration of GAD65-specific T-cells. Primary cultures of human vascular ECs expressing the DRB1*0401 (VEC1) and DRB1*0301 (VEC2) genotypes were established and de novo expression of HLA class II molecules induced with interferon-gamma. Under these conditions, VEC1 efficiently processed and presented whole GAD65 to the HLA-DR4-restricted murine T-cell hybridoma T33.1 that recognizes the 274-286 epitope of GAD65. Using a transwell system, we examined the effect of GAD65 presentation on migration of GAD65-specific T-cells across EC monolayers. Migration of T33.1 hybridoma cells and of the human T-cell clone, PM1#11 (recognizes GAD65 epitope 339-352 presented by HLA-DR3) across VEC1 and VEC2, respectively, were greatly enhanced in the presence of GAD65, commencing more rapidly and achieving a higher peak migration at 3 h. Migrated PM1#11 cells retained full proliferative capacity. These results support the hypothesis that presentation of autoantigens by islet endothelium in vivo could promote transmigration of circulating islet autoantigen-specific T-cells primed in regional lymph nodes against islet autoantigens.

Antinuclear autoantibodies (ANA) in Gulf War-related illness and chronic fatigue syndrome (CFS) patients

It is established that veterans of the 1991 Gulf War have an increased frequency of experiencing multiple symptoms. The underlying mechanism of these ailments is unclear, although they do not correspond to any clearly defined syndrome. The most common symptoms overlap with those of chronic fatigue syndrome (CFS). CFS was recently associated with a novel subtype of antinuclear autoantibody (ANA) that reacts with nuclear envelope (NE) antigens. NE autoantibodies are not known to be linked with any distinct clinical condition, but have been observed in patients with unusual mixed chronic autoimmune disorders and connective tissue diseases. In this study we examined whether NE ANAs are a feature of patients with CFS and symptomatic Gulf War veterans (sGWV). We studied the prevalence of ANA in 130 sGWV, 90 well Gulf War veterans (wGWV), 128 symptomatic Bosnia and Era veterans (sBEV), 100 CFS patients, and 111 healthy control subjects matching for age and sex. We found no significant difference in the prevalence of ANAs between any of the groups. None of the patients/or veterans we studied had ANA of the NE type. Our results show that multisymptom illness due to CFS or related to Gulf War service is not associated with antinuclear autoimmunity.

Characterization of the T-cell response to coxsackievirus B4: evidence that effector memory cells predominate in patients with type 1 diabetes

Most of the evidence linking enterovirus (EV) infection with the development and/or acceleration of type 1 diabetes is indirect. Few studies have examined T-cell responses to these viruses, and therefore the nature of the viral targets and the immune cells involved in antiviral responses remain unclear. In the present study, we examined the characteristics of the T-cell response to the EV Coxsackievirus B4 (CVB4) in patients with type 1 diabetes and healthy control subjects. We find that CVB4-specific T-cells preferentially target the envelope proteins VP1, VP2, and VP3, and that the response to these and other CVB4 proteins differs markedly in type 1 diabetic patients compared with nondiabetic control subjects. The frequency of T-cell proliferative responses against VP2 was significantly reduced in type 1 diabetic patients compared with control subjects, especially in patients tested near to diagnosis (P < 0.001). In contrast, median levels of gamma-interferon (IFN-gamma) production by T-cells in response to the CVB4 antigens tested were generally high in new-onset type 1 diabetic patients, who produced significantly higher levels in response to VP3 compared with healthy subjects (P < 0.05) and patients with long-standing disease (P < 0.05). New-onset type 1 diabetic patients also had higher levels in response to P2C compared with healthy subjects (P < 0.005) and to VP2 compared with patients with long-standing disease (P < 0.05). These results suggest that the quality of the immune response to CVB4 antigens differs significantly between type 1 diabetic patients and control subjects, with a predominance of primed effector (IFN-gamma-producing) memory cells near to disease diagnosis. The data are consistent with the notion that the diagnosis of type 1 diabetes is associated with recent or persistent exposure to EV antigens.

3 beta hydroxysteroid dehydrogenase autoantibodies in patients with idiopathic premature ovarian failure target N- and C-terminal epitopes

The steroid cell enzyme 3 beta hydroxysteroid dehydrogenase (3 beta HSD) has been identified as a target of steroid cell autoantibodies, and autoantibodies to this enzyme are present in patients with premature ovarian failure and patients with autoimmune polyendocrine syndrome 1. The aim of the present study was to develop a radioligand binding assay for 3 beta HSD autoantibodies and to exploit this to examine regions of the molecule targeted by autoantibodies. We generated a construct of 3 beta HSD coupled to a luciferase fusion partner in order to maximize the yield of (35)S-radiolabeled protein. Labeled 3 beta HSD was then immunoprecipitated and the autoantibodies quantified by phosphoimaging. Autoantibodies to 3 beta HSD were detected in 12 of 100 (12%) idiopathic premature ovarian failure patients and 0 of 103 (0%) healthy age-matched controls (P < 0.0001). Three overlapping fragments of 3 beta HSD cDNA were cloned downstream of luciferase to examine autoantibody binding sites. Two of nine sera with 3 beta HSD autoantibodies (22%) displayed reactivity to the N terminus of 3 beta HSD, and seven (77%) showed reactivity to the C terminal; no sera reacted with the middle region. Our study demonstrates a markedly enhanced disease specificity of autoantibodies to 3 beta HSD detected using this novel assay and shows that distinct regions of the molecule are targeted.

T cell activation by coxsackievirus B4 antigens in type 1 diabetes mellitus: evidence for selective TCR Vbeta usage without superantigenic activity

Numerous clinical and epidemiological studies link enteroviruses such as the Coxsackie virus group with the autoimmune disease type 1 diabetes mellitus (DM). In addition, there are reports that patients with type 1 DM are characterized by skewing of TCR Vbeta chain selection among peripheral blood and intraislet T lymphocytes. To examine these issues, we analyzed TCR Vbeta chain-specific up-regulation of the early T cell activation marker, CD69, on CD4 T cells after incubation with Coxsackievirus B4 (CVB4) Ags. CD4 T cells bearing the Vbeta chains 2, 7, and 8 were the most frequently activated by CVB4. Up-regulation of CD69 by different TCR families was significantly more frequent in new onset type 1 DM patients (p = 0.04), 100% of whom (n = 8) showed activation of CD4 T cells bearing Vbeta8, compared with 50% of control subjects (n = 8; p = 0.04). T cell proliferation after incubation with CVB4 Ags required live, nonfixed APCs, suggesting that the selective expansion of CD4 T cells with particular Vbeta chains resulted from conventional antigen processing and presentation rather than superantigen activity. Heteroduplex analysis of TCR Vbeta chain usage after CVB4 stimulation indicated a relatively polyclonal, rather than oligo- or monoclonal response to viral Ags. These results provide evidence that new-onset patients with type 1 DM and healthy controls are primed against CVB4, and that CD4 T cell responses to the virus have a selective TCR Vbeta chain usage which is driven by viral Ags rather than a superantigen.

Characterization of preparations of GAD65, proinsulin, and the islet tyrosine phosphatase IA-2 for use in detection of autoreactive T-cells in type 1 diabetes: report of phase II of the Second International Immunology of Diabetes Society Workshop for Standardization of T-cell assays in type 1 diabetes

The identification, quantification, and characterization of T-cells reactive with the islet autoantigens GAD65, proinsulin (PI), and tyrosine phosphatase-like molecules IA-2 and phogrin are major research goals in type 1 diabetes. In the Immunology of Diabetes Society First Workshop on Autoreactive T-Cells, the quality of recombinant preparations of these autoantigens was identified as a significant weakness, a finding that may account for much of the inconsistency in published studies of peripheral blood T-cell reactivity to islet autoantigens. Poor antigen quality has also hampered the development of novel technologies for the detection of islet-reactive T-cells. For these reasons, in the present study, several preparations of GAD65, PI, and IA-2 were collected and evaluated for endotoxin content, ability to stimulate a panel of relevant T-cell clones, and inhibitory effects on proliferation to unrelated third-party antigens. Through this process, we have been able to identify preparations of GAD65 and IA-2, generated in insect cells using the baculovirus expression system, that stimulate relevant clones and display low inhibitory effects on third-party antigens. In addition, we characterized a PI preparation generated in bacteria as being free of effects on proliferation to third-party antigens and low in endotoxin content. These preparations are important to promote the development of robust and sensitive assays of islet-reactive T-cells in patients with type 1 diabetes or patients at high risk for developing the disease.

Lack of association between HLA genotype and chronic fatigue syndrome

Although the aetiology of chronic fatigue syndrome is controversial, evidence that infective agents including viruses may have a role in the development of the condition has led to studies seeking an association with the immunomodulatory HLA genes. In the present study, we sought to extend previous work using a well-characterized patient group and modern HLA genotyping techniques. Fifty-eight patients were phenotyped for HLA A and B by microcytotoxicity and genotyped for HLA DRB, DQB and DPB by PCR oligoprobing, and the frequencies of antigens so assigned were compared with those from a control group of 134. No significant differences in HLA frequencies were found between patient and control groups. Thus, this study does not confirm previous findings of an HLA association with chronic fatigue syndrome, suggesting that neither presentation of viral antigen by HLA class I nor antigen processing genes in the HLA region is a major contributory factor in the development of the disease.

T-Cell reactivity to the P2C nonstructural protein of a diabetogenic strain of coxsackievirus B4

Enteroviruses are proposed as initiating factors in the etiology of Type 1 diabetes mellitus (Type 1 DM). Molecular mimicry between the autoantigen glutamic acid decarboxylase 65 (GAD65) and the coxsackievirus B4 (CVB4) nonstructural protein P2C is frequently cited as a mechanism by which this virus triggers the disease, but little is known about the immunogenicity of this viral protein in humans, mainly due to the problem of obtaining highly pure preparations of P2C. We generated large amounts of highly pure, soluble P2C protein, coupled to the fusion partner maltose binding protein (MBP-P2C) using the PMAL-c2 bacterial expression plasmid and a two-step purification system comprising amylose resin and ion exchange. Using purified viral protein we show that specific T-cell responses against P2C are detected in the blood of healthy donors and Type 1 DM patients. Proliferation responses to P2C were detected only in subjects also demonstrating T-cell proliferation to CVB4 Vero cell lysates. However, in additional cases T-cell responses to P2C were detectable through the release of interferon-gamma or interleukin-4 in individuals who did not make proliferative responses. Taken together, our data show that the P2C nonstructural protein of CVB4 is targeted by T cells during the antiviral immune response and may trigger the production of T helper 1 and T helper 2 cytokines. The availability of pure, immunogenic P2C should allow the putative role of antiviral responses in the development of autoimmune diabetes to be investigated.

Naturally processed and presented epitopes of the islet cell autoantigen IA-2 eluted from HLA-DR4

During immune responses, antigen-presenting cells (APCs) process antigens and present peptide epitopes complexed with human leukocyte antigen (HLA) molecules. CD4 cells recognize these naturally processed and presented epitopes (NPPEs) bound to HLA class II molecules. Epitope identification is important for developing diagnostic and therapeutic tools for immune-mediated diseases and providing insight into their etiology, but current approaches overlook effects of natural processing on epitope selection. We have developed a technique to identify NPPEs using mass spectrometry (MS) after antigen is targeted onto APCs using a lectin-based antigen delivery system (ADS). We applied the technique to identify NPPEs of the intracellular domain of the type 1 diabetes mellitus-associated (type 1 DM-associated) autoantigen insulinoma-associated-2 (IA-2ic), presented by HLA-DR4 (0401). IA-2ic-derived NPPEs eluted from HLA-DR4 constitute 6 sets of peptides nested around distinct core regions. Synthetic peptides based on these regions bind HLA-DR4 and elicit primary T-cell proliferation frequently in HLA-DR4-positive type 1 DM patients, but rarely in non-HLA-DR4 patients, and in none of the HLA-DR4 nondiabetic controls we tested. This flexible, direct approach identifies an HLA allele-specific map of NPPEs for any antigen, presented by any HLA class II molecule. This method should enable a greater understanding of epitope selection and lead to the generation of sensitive and specific reagents for detecting autoreactive T cells.

Prevalence of autoantibodies to autonomic nervous tissue structures in Type 1 diabetes mellitus

AIMS

The pathogenesis of diabetic autonomic neuropathy is multifactorial, but recent studies have suggested a link between the presence of autoantibodies to nervous tissue structures and severe, symptomatic autonomic neuropathy. The present study was designed to examine the true prevalence of these autoantibodies in a large clinic-based population of Type 1 diabetic patients compared to nondiabetic controls.

METHODS

The presence of complement fixing autoantibodies to vagus nerve (CF-VN), sympathetic ganglion (CF-SG) and adrenal medulla (CF-ADM) was assessed by immunofluorescence in a large cohort of patients (n = 394) of varying duration of Type 1 DM (median 28 years, range 6 months to 73 years) and 160 age and sex-matched nondiabetic control subjects.

RESULTS

All three autoantibodies were frequently detected in Type 1 DM (CF-VN, 22.1%; CF-SG, 30.7%; CF-ADM, 13.2%) but only rarely in healthy control subjects (4.4%, 4.4% and 3.1%, respectively; P < 0.0005 for all). There was no association between any of the autoantibodies and retinopathy (fundoscopy), peripheral somatic neuropathy (biothesiometry) or nephropathy (urinary albumin-creatinine ratio).

CONCLUSIONS

Our results on this large cohort establish the extensive presence of autonomic nervous tissue autoantibodies in Type 1 DM. Their role in reflecting, causing or predicting autonomic neuropathy remains to be determined.

Spontaneous T-cell proliferation in the non-obese diabetic mouse to a peptide from the unique class II MHC molecule, I-Ag7, which is also protective against the development of autoimmune diabetes

AIMS/HYPOTHESIS

Major histocompatibility complex class II molecules present antigenic peptides to T-cells and have an important role in T-cell thymic education. The mechanism by which major histocompatibility complex alleles confer a high genetic risk for autoimmune diabetes is not known. One hypothesis is that during positive thymic selection, the peripheral T-cell repertoire is modelled by major histocompatibility complex-restricted presentation of self major histocompatibility complex molecule-derived peptides, some of which mimic tissue autoantigens. The sequence similarity between a known T-cell epitope of glutamic acid decarboxylase-65, 509:VPPSLRTLED and the non-obese diabetic mouse class II major histocompatibility complex molecule I-Ag7 86:VPTSLRRLEQ is consistent with this.

METHODS

We measured spontaneous proliferation of peripheral T-cells from non-obese diabetic mice and other, non-diabetes-prone strains, to the I-Ag7 86-101 and glutamic acid decarboxylase-65(509-524) peptides, binding of these peptides to intact I-Ag7 and assessed the effect of tolerance induction on diabetes development, by injecting young non-obese diabetic mice with high doses of peptide.

RESULTS

T-cells from non-obese diabetic, but not other mice strains, spontaneously proliferate to the I-Ag7 86-101 and glutamic acid decarboxylase-65(509-524) peptides, but not control peptides. Both test peptides bind I-Ag7. Tolerance induction prolongs diabetes-free survival in non-obese diabetic mice when either the I-Ag7 86-101 or glutamic acid decarboxylase-65(509-524) peptide, but not control peptide, is used.

CONCLUSION/INTERPRETATION

A peptide from the unique class II major histocompatibility complex, diabetes-susceptibility molecule, I-Ag7, presented by I-Ag7 is a target of T-cell responses in diabetes-prone nonobese diabetic mice and tolerance induction against the peptide offers appreciable protection against the development of diabetes.

Neutrophil response to Neisseria meningitidis: inhibition of adhesion molecule expression and phagocytosis by recombinant bactericidal/permeability-increasing protein (rBPI21)

Polymorphonuclear neutrophil (PMNL) activation enhances microbial clearance but also contributes to the vascular damage and multiorgan failure associated with severe meningococcal sepsis. By use of a whole blood model of meningococcal bacteremia, loss of PMNL L-selectin and up-regulation of CD11b was observed in response to Neisseria meningitidis serogroups B and C, which is followed by opsonophagocytosis. PMNL priming with either Escherichia coli lipopolysaccharide (LPS) or FMLP prior to meningococcal challenge resulted in enhancement of both PMNL L-selectin shedding (1.5- to 4-fold) and phagocytosis (2- to 3-fold). Blockade of meningococcal LPS lipid A with recombinant bactericidal/permeability-increasing protein (rBPI21) resulted in partial inhibition of the PMNL activation and phagocytosis response to N. meningitidis. The effect of rBPI21 was reversed by excess E. coli LPS or FMLP. It is proposed that PMNL priming by N. meningitidis results in an exaggerated activation and phagocytosis response to the organism.

Human leukocyte antigen-DQB1* genotypes encoding aspartate at position 57 are associated with 3beta-hydroxysteroid dehydrogenase autoimmunity in premature ovarian failure

Premature ovarian failure (POF) has an autoimmune pathogenesis in a significant proportion of cases. Autoantibodies to the steroid cell enzyme, 3beta-hydroxysteroid dehydrogenase (3betaHSD) are present in one fifth of patients and may identify an autoimmune subgroup. As autoimmune diseases are associated with alleles of the human leukocyte antigen (HLA) genes, we examined the distribution of HLA-DRB1 and -DQB1 genotypes in 118 women with POF, of whom 21% had 3betaHSD autoantibodies, and 134 racially matched control subjects. Two HLA-DQB1 alleles, 0301 and 0603, were associated with 3betaHSD autoantibody positivity (P = 0.04 and P = 0.006, respectively). As the DQB1*0301 and -0603 genes share an identical codon at position 57 (aspartate, Asp), we analyzed the frequency of DQbeta-Asp57 encoding DQB1 genes in our series. Eighteen of 21 POF patients with 3betaHSD autoantibodies had DQbeta-Asp57-encoding genotypes (haplotype frequency, 27 of 42; 64%) compared with 92 of 134 control subjects (haplotype frequency, 109 of 268; 41%; P = 0.004), and 9 of 21 (43%) cases were homozygous for codon 57 genotypes compared with 17 of 134 (13%) control subjects (P = 0.0006). These probability values were not significant after correction for multiple testing, and these trends will therefore require confirmation in larger cohorts. HLA class II molecules present antigenic peptides to CD4+ T lymphocytes. DQbeta57 occupies a key site at the boundary of the peptide binding groove, with a major impact on peptide binding. Our preliminary demonstration of an association between POF, 3betaHSD autoimmunity, and a distinctive HLA-DQ molecule supports the hypothesis that autoantibodies to this steroid cell enzyme may be markers of autoimmune ovarian failure and suggests that presentation of autoantigenic or external peptides to T lymphocytes by HLA-DQ molecules with Asp57-beta-chains is important in the pathogenesis of this disease.

Autoimmunity in diabetic autonomic neuropathy: does the immune system get on your nerves?

Symptomatic autonomic neuropathy is a devastating occasional complication of diabetes mellitus, especially Type 1. Although the full-blown clinical syndrome is not common, dysfunction of the autonomic nerves is detectable in up to 40% of Type 1 diabetic patients but its aetiopathogenesis is poorly understood. There is evidence to suggest that the damage to the autonomic nerves may be immune-mediated. This evidence is reviewed in the following article.

Autonomic function and autoantibodies to autonomic nervous structures, glutamic acid decarboxylase and islet tyrosine phosphatase in adolescent patients with IDDM

Recent studies have linked autoimmunity to nervous tissue structures and diabetic autonomic neuropathy, but data on the early stage of IDDM and on the natural history of this association are not available. For this reason, we investigated autonomic nervous function, and the presence of autoantibodies to sympathetic and parasympathetic nervous structures, to glutamic acid decarboxylase (GAD) and tyrosine phosphatase (IA-2/ICA512) in 85 adolescents with insulin-dependent diabetes mellitus (IDDM) (mean age 14.7+/-1.6 yr, mean duration of diabetes 6.8+/-3.5 yr), and 45 age and sex-matched healthy subjects. Nervous tissues autoantibodies were detected using an indirect immunofluorescent complement-fixation technique, with monkey adrenal gland, rabbit cervical ganglia and vagus nerve as substrates. GAD and IA-2/ICA512 autoantibodies were detected by radioimmunoprecipitation assay. Seven patients (8%) had anti-vagus nerve autoantibodies, 7 other patients (8%) had anti-cervical ganglia autoantibodies, while all controls were negative (P < 0.05). Anti-adrenal medulla antibodies were detected in 16 patients (19%) and in 2 control subjects (P<0.02). None of the patients had autonomic symptoms. When patients were divided according to the presence or absence of autoantibodies, values of the cardiovascular tests (deep breathing, 30:15 ratio, Valsalva ratio) were similar in the two groups and similar to those in healthy subjects. However, when considered together, patients positive for one or more autoantibody showed a trend for lower values of deep breathing test and 30:15 ratio test, compared with healthy control subjects, which failed to reach conventional significance values (P=0.17 and P=0.07, respectively). No correlation was found between cardiovascular parameters and metabolic control or diabetes duration. There was no association between autoimmunity to nervous tissue structures and presence of GAD and IA-2/ICA512 Ab, and no correlation between these two autoantibodies and values of cardiovascular tests. Our data indicate that autonomic dysfunction is not a characteristic of young diabetic patients, but that autoantibodies against autonomic nervous structures are present during the first 1 to 15 yr of diabetes. GAD and tyrosine phosphatase appear to be excluded as target autoantigens within autonomic structures. Follow-up studies are required to evaluate future autonomic dysfunction and symptoms in these patients, and to establish whether the subtle autonomic dysfunction detected and/or the nervous tissue autoantibodies, are predictive of the development of this complication.

Enhanced T cell proliferation and increased responder frequency following delivery of antigen to the antigen-presenting cell; B cell dependency and use in detection of autoreactive T cells

Reported frequencies of peripheral blood autoantigen-specific cells in autoimmune diseases are typically low, which could be due to true scarcity or to limitations of in vitro assays. In the present study, antigens were targeted to the antigen-presenting cell (APC) to enhance T cell proliferation, using an antigen delivery system (ADS), consisting of biotinylated anti-IgG, streptavidin and biotinylated antigen. This was able to bind B cells and monocytes and was internalized within 24 hours. T cell proliferation to tetanus toxoid was at least doubled using the ADS compared to conventional assay with antigen in simple solution. To evaluate the ADS in an autoimmune disease, we determined T cell responses to the insulin-dependent diabetes mellitus (IDDM)-associated autoantigen IA-2ic in patients with recent-onset IDDM. When IA-2ic was available conventionally in solution, proliferation was poor, but significantly higher in IDDM patients than control subjects. However, the ADS significantly enhanced proliferation by a mean 3-fold for all subjects, while maintaining the significant difference between IDDM patients and healthy controls. Increases in T cell proliferation via the ADS were due to the recruitment of approximately 3 times the number of CD4 + T cells stimulated in conventional assays. B cell depletion abolished enhancement suggesting that the ADS operates through recruitment of B cells as APCs. This flexible modification of the T cell assay offers greatly enhanced sensitivity for determining the frequency of antigen and autoantigen-reactive T cells.

Cytokine overproduction in healthy first degree relatives of patients with IDDM

Healthy family members of patients with insulin-dependent diabetes mellitus (IDDM) are known to share a number of immunological abnormalities with their affected relatives. Since monocyte and type 1 T-cell-derived cytokines contribute to the pathogenesis of IDDM, we studied the production of these cytokines in the healthy first degree relatives of 29 children with IDDM. We report that circulating tumour necrosis factor-alpha (TNF-alpha) and soluble interleukin-2 (sIL-2) receptor were present in increased amounts in non-diabetic family members at levels similar to those found in the diabetic children (duration of disease 3 months-5 years). Furthermore, marked hypersecretion of IL-1alpha and TNF-alpha by mitogen-stimulated peripheral blood mononuclear cells was found in both diabetic and healthy family members. Abnormalities of cytokine production in healthy relatives did not correlate with the presence of islet cell antibodies or with HLA DR type. These data indicate that healthy family members of patients with IDDM exhibit overproduction of a number of cytokines that have been implicated in diabetogenesis.

Combined analysis of GAD65 and ICA512(IA-2) autoantibodies in organ and non-organ-specific autoimmune diseases confers high specificity for insulin-dependent diabetes mellitus

There is evidence that insulin-dependent diabetes mellitus (IDDM) may develop in association with other non-beta-cell-specific autoimmune diseases. We aimed to assess whether autoantibodies to the islet cell antigens glutamic acid decarboxylase (Mr 65,000 isoform) (GAD65) and ICA512(IA-2), present alone or in combination, are limited to IDDM or also occur in other organ- or non-organ-specific autoimmune disorders. We determined the frequency of these autoantibodies by radioimmunoassay in 199 sera from patients with autoimmune thyroid diseases (AITD), rheumatoid arthritis (RA), systemic lupus erythematosus (SLE) and primary biliary cirrhosis (PBC), and compared the results with those from 507 newly diagnosed patients with IDDM and 280 healthy controls. ICA512(IA-2) autoantibodies were detected exclusively in AITD with concurrent IDDM, but not in other autoimmune diseases without IDDM, whereas GAD65 autoantibodies exceeded the limit of normal in 67.7% (21 of 31) of patients with AITD who also had IDDM and in 5.5% (three of 55) of patients with PBC. The frequency of either GAD65 and/or ICA512(IA-2) autoantibodies was significantly higher in patients with AITD who also had IDDM (27 of 31, 87.1%) than in those with AITD alone (one of 53, 1.9%; P<10(-6)), but was not significantly different from those patients with newly diagnosed IDDM (418 of 507, 82.4%). Neither patients with organ- or non-organ-specific autoimmune diseases without IDDM nor healthy controls had autoantibodies against both GAD65 and ICA512(IA-2). Despite the fact that one of the two autoantibodies was occasionally detected in patients with non-beta-cell-specific autoimmune diseases without IDDM, combined determination of GAD65 and ICA512(IA-2) autoantibodies specifically identified IDDM in the majority of patients with AITD. In conclusion, because of the strong association of IDDM with AITD, testing for multiple islet autoanti-bodies could be useful as a predictive marker for risk of progression to IDDM onset amongst patients with autoimmune thyroid disorders.

Lymphocyte vaccination protects prediabetic non-obese diabetic mice from developing diabetes mellitus

In the therapeutic manoeuvre termed "lymphocyte vaccination", activated lymphocytes capable of transferring an autoimmune disease are instead attenuated and given in vaccine form. We have previously shown that such a therapy administered to non-obese diabetic (NOD) mice at 6 weeks of age prevents diabetes mellitus. To assess whether this therapy has potential clinical relevance, in the present study lymphocyte vaccination was applied in NOD mice in 3 weekly doses commencing in the immediate prediabetic period (age 12 weeks), when insulitis is advanced and diabetes incipient. Of 30 NOD mice receiving active vaccine (composed of attenuated lymphocytes from diabetic NOD mice) 13 (43.3%) remained non-diabetic to the age of 30 weeks, in comparison with 2 of 30 (6.7%; p < 0.01) mice receiving a control vaccine (composed of attenuated lymphocytes from non-diabetic NOD/B10 mice) and 5 of 26 (19.2%; p < 0.01) mice receiving saline carrier alone. Moreover, in an additional group of 10 NOD mice receiving active vaccine weekly between 12 and 30 weeks, 8 remained diabetes free at the end of the treatment. The most notable effect of the vaccine was that the delay in diabetes onset was accompanied by a reduction in insulitis and in some cases a complete absence of infiltrating lymphocytes at 30 weeks of age. Immunocytochemistry indicated that when present, islet infiltrating lymphocytes in non-diabetic mice that received active vaccine showed significantly reduced staining for interferon-gamma, compared with the infiltrate seen in diabetic mice receiving the control vaccine or saline. This study demonstrates that the rapid progression to diabetes typically seen in 12-week-old NOD mice can be delayed by lymphocyte vaccination, supporting the possibility that a vaccine composed of attenuated autologous peripheral blood lymphocytes could be effective in high risk first degree relatives of patients with insulin dependent diabetes mellitus.

Expression of glutamic acid decarboxylase in nervous tissue structures targeted by autoantibodies in patients with diabetic autonomic neuropathy

We have previously identified an association between symptomatic diabetic autonomic neuropathy (DAN) and autoantibodies to sympathetic and parasympathetic nervous structures. The antigens identified by these autoantibodies are not known, but glutamic acid decarboxylase (GAD) has been suggested as a candidate target, since anti-GAD autoantibodies are present in patients with long-term diabetes and GAD is expressed in a variety of cell types and structures in the nervous system. The aim of this study was to examine GAD expression in sympathetic ganglia and vagus nerve and to compare the distribution of GAD within these tissues with that of anti-sympathetic ganglia and anti-vagus nerve autoantibodies from patients with DAN, using single and double indirect immunofluorescence on tissue sections. The monoclonal antibody GAD-6, specific for GAD65, gave a granular, peripheral, cytoplasmic staining pattern in sympathetic ganglion cells. Dual immunofluorescence demonstrated that serum from a patient with anti-sympathetic ganglion autoantibodies stained the same cells, but homogeneously throughout the cytoplasm. In the vagus nerve, patient's serum stained the fibres only; GAD-6 stained the cytoplasm of parasympathetic ganglion cells but only occasional fibres. In addition, GAD enzymatic activity was detectable in both sympathetic ganglia and vagus nerve. Incubation of sera or GAD-6 overnight with a crude homogenate of human brain as an antigen source abolished staining of the nervous tissues by GAD-6, but not by patients' sera. The different localisation of GAD and the autoantigens targeted by patients' sera indicates that GAD is not the target of the autoantibodies characteristic of DAN. Moreover, absorption studies using human brain homogenate suggest that the targets of anti-sympathetic ganglion and anti-vagus nerve autoantibodies are absent or represented only at low levels in the central nervous system and may be confined to the periphery.

Reproducibility and persistence of neural and adrenal autoantibodies in diabetic autonomic neuropathy

The presence of autoantibodies to autonomic nervous tissue structures is a feature of patients with symptomatic diabetic autonomic neuropathy. It has not been established whether these autoantibodies cause, contribute to or simply reflect nervous tissue damage. Serum samples were tested for the presence of complement-fixing autoantibodies to adrenal medulla, vagus nerve, and sympathetic ganglion cells, to demonstrate: (a) reproducibility of the technique, (b) persistence of the antibodies, and (c) whether or not they occur in patients with non-insulin-dependent (Type 2) diabetes (NIDDM) with neuropathy. Examination of 37 samples, by different observers 2 years apart, revealed a high degree of concordance of both positive and negative results, demonstrating the method of testing to be highly reproducible. Re-testing of 37 patients (by analysing a second blood sample) between 0.5 and 2.7 years (mean 1.7 years) after their first test also demonstrated that antibodies, once present, normally persist; and that most patients initially negative remained so. Of 17 neuropathic NIDDM patients, 16 were negative for all three antibodies, indicating their rarity in this group of patients.

T lymphocyte subpopulations in anorexia nervosa and refeeding

Several studies have addressed the question of the effects of starvation on immune function and changes in lymphocyte subsets. Patients with anorexia nervosa are severely malnourished, but there have been few studies of immune parameters in this group. For this reason, phenotypic markers of T cell function and activation were studied in 20 severely underweight patients with anorexia nervosa and again after a period of refeeding. The most significant finding was a reduction in the percentage and absolute number of CD8+ T cells in patients with anorexia, the result of a marked reduction in memory (CD45RO+RA-) CD8 cells. A tendency for recovery in numbers of this subset was seen after refeeding. A decreased memory:maive cell ratio was also seen among CD4 cells, but was less marked. Subtle abnormalities in activated CD4 and CD8 cells were also found in the patient group at the initial sampling, but did not follow any clear pattern. These findings indicate that starvation in anorexic patients is accompanied by a large change in memory CD8 T cells. It may be speculated that this relates to the perceived lack of symptomatic common viral infections in underweight anorexic patients and their return with the recovery of weight.

Irradiated NC adenocarcinoma cells transduced with both B7.1 and interleukin-2 induce CD4+-mediated rejection of established tumors

Previous studies have shown that expression of the immune co-stimulator B7.1 reduces the tumorigenicity of some, but not all, malignant cell lines. However, B7.1-expressing tumor cells are not very effective in inducing the rejection of established tumors. This may in part be due to induction of anergy in the potentially reactive T cells. Previous studies have shown that IL-2 can reverse the anergic state both in vitro and in vivo. Therefore, we have examined the effect of retrovirus-mediated delivery and expression of murine B7.1 and interleukin-2 on tumor formation and rejection of established MHC class I+/II- NC adenocarcinomas. Neither the expression of B7.1 nor IL-2 alone had a significant effect on NC tumorigenicity. In contrast, combined expression of B7.1 and IL-2 substantially decreased the tumorigenicity of these cells in the immunecompetent syngeneic hosts. T-cell depletion studies show this to be dependent primarily on the activation of CD4+ cells. Furthermore, distant subcutaneous injection of irradiated NC/IL-2/B7.1 can induce, much more effectively than NC/B7.1 or NC/IL-2, the rejection of small NC tumors, and prevent the recurrence of large surgically resected tumors. Together, these results suggest that tumor cells genetically modified to express B7.1 and IL-2 can induce the immune-mediated rejection of established class II- tumors by a mechanism involving CD4+ cells.

Clinical improvement in chronic fatigue syndrome is not associated with lymphocyte subsets of function or activation

The relationship between markers of immune function and chronic fatigue syndrome (CFS) is controversial. To examine the relationship directly, 43 subjects with CFS entering a randomized controlled trial of a nonpharmacological treatment for CFS gave samples for immunological analysis before and after treatment. Percentage levels of total CD3+ T cells, CD4 T cells, CD8 T cells, and activated subsets did not differ between CFS subjects and controls. Naive (CD45RA+ RO-) and memory (CD45RA- RO+) T cells did not differ between subjects and controls. Natural killer cells (CD16+/CD56+/CD3-) were significantly increased in CFS patients compared to controls, as was the percentage of CD11b+ CD8 cells. There were no correlations between any immune variable and measures of clinical status, with the exception of a weak correlation between total CD4 T cells and fatigue. There was a positive correlation between memory CD4 and CD8 T cells and depression scores and a negative correlation between naive CD4 T cells and depression. No immune measures changed during the course of the study, and there was no link between clinical improvement as a result of the treatment program and immune status. Immune measures did not predict response or lack of response to treatment. In conclusion, we have been unable to replicate previous findings of immune activation in CFS and unable to find any important associations between clinical status, treatment response, and immunological status.

Identification of 3 beta-hydroxysteroid dehydrogenase as a novel target of steroid cell autoantibodies: association of autoantibodies with endocrine autoimmune disease

Autoantibodies directed against steroid hormone-producing cells (SCA) detectable by immunofluorescence are typically found in a small proportion of patients with premature ovarian failure (POF) as well as in other endocrine autoimmune diseases. The SCA pattern stains cells in the outer zones of the adrenal cortex, ovary, and testis. To identify the molecular target of SCA, an adrenal complementary DNA expression library was screened using SCA-positive serum, and the steroid enzyme 3 beta-hydroxysteroid dehydrogenase (3 beta HSD) was identified. Only 1 of 48 (2%) patients with idiopathic POF, not pre-selected for the presence of other autoimmune diseases, had SCA by immunofluorescence, whereas 10 of 48 (21%) had anti-3 beta HSD autoantibodies detectable by immunoblot using recombinant human enzyme compared with 6 of 115 (5%) control subjects (P = 0.002). Absorption of SCA-positive serum with recombinant human 3 beta HSD abolished the immunofluorescence pattern. We also examined the prevalence of anti-3 beta HSD autoantibodies in other endocrine autoimmune diseases. Two of 112 (2%) diabetic patients, but none of the thyroid or Addisonian patients, had SCA by immunofluorescence. Twenty-six (23%) diabetic subjects (P < 0.001 vs. controls), 3 of 18 thyroid patients (P > 0.05 vs. controls), and none of 4 Addisonian patients had anti-3 beta HSD autoantibodies. 3 beta HSD is the first steroid cell autoantigen defined at the molecular level to be associated with idiopathic POF occurring in the absence of other polyglandular diseases. Autoantibodies to 3 beta HSD in patients with other organ-specific autoimmune diseases indicate that the enzyme behaves as a typical target of polyendocrine autoimmunity. Anti-3 beta HSD autoantibodies in patients with POF may provide a marker of those subjects whose ovarian failure is autoimmune in origin and, as recent studies suggest, may be salvageable with glucocorticoid treatment.