Autoimmune disease and the major histocompatibility complex: therapeutic implications

Reaction of Lectin-Specific Antibody with Human Tissue: Possible Contributions to Autoimmunity

The aim of this study was to examine the direct reaction of specific lectin/agglutinin antibodies to different tissue antigens to confirm the theory that reactivity between them may contribute to autoimmunities. Lectins are carbohydrate-binding proteins found in nearly all fruits and vegetables. Undigested lectins can penetrate the gut barriers, provoking an immune response that results in the production of antibodies against them. Using an enzyme-linked immunosorbent assay, we reacted lectin-specific antibodies with 62 different tissue antigens. Wheat germ agglutinin-specific antibody was the most reactive with the tissue antigens (37 tissues out of 62), followed by red kidney bean phytohemagglutinin-specific antibody (20), soybean agglutinin-specific antibody (20), and peanut agglutinin-specific antibody (15). This reaction between anti-lectin antibodies and many human tissue antigens may be due to possible molecular mimicry and cross-reactivity. After our results confirmed that anti-lectin antibodies bind with human tissues, we wanted to determine the prevalence of these antibodies in the blood of 500 nominally healthy donors. The percentage elevation of antibodies against different lectins ranged from 12 to 16% (Immunoglobulin G), 9.7-14.7% (Immunoglobulin A), 12-18% (Immunoglobulin M), and 7.8-14.6% (Immunoglobulin E). Serial dilutions and inhibition study confirmed that these reactions were specific. Finally, we tested the lectin-specific antibody level in sera both negative and positive for RF and ANA and found that IgM anti-lectin antibody levels were highly correlated with RF but not with ANA level. The reaction of anti-lectin antibodies with human tissue components and their detection in RF-positive samples may describe mechanisms by which the production of antibodies against undigested lectins may contribute to the pathogenesis of some autoimmune diseases.

Prevalence of thyroid autoimmunity in first-degree relatives of patients with celiac disease

AIM

Patients with celiac disease (CeD) are prone to develop other autoimmune diseases such as autoimmune thyroid disease and type 1 diabetes. While 7.5% of first-degree relatives (FDRs) of patients with CeD develop CeD, it is not clear whether FDRs of patients with CeD are at higher risk of developing autoimmune thyroid disease.

METHODS

In this prospective case-control study, we recruited 194 FDRs (males 53.1%) of 91 patients with CeD and 140 age-matched healthy controls (males 76.4%). They were screened for CeD using anti-tissue transglutaminase antibodies (anti-tTG Ab) and thyroid disease using a symptom questionnaire, anti-thyroid peroxidase antibodies (anti-TPO) and serum thyroid-stimulating hormone (TSH). Subjects having positive anti-TPO but a normal TSH were classified as having thyroid autoimmunity and those with elevated TSH with or without positive anti-TPO Ab were classified as having autoimmune thyroid dysfunction.

RESULTS

The prevalence of thyroid autoimmunity and autoimmune thyroid dysfunction in FDRs was significantly higher than that in healthy controls (17.5% vs. 5.0%, p < 0.01; 11.8% vs. 3.5%, p < 0.01), respectively. A significantly higher number of FDRs had a positive anti-tTG Ab in comparison with controls (13.9% vs. 2.2%, p < 0.001). Amongst FDRs having thyroid autoimmunity, 44.1%, 47.0% and 8.8% were siblings, parents and children of patients with CeD, respectively. Familial clustering was seen only in 1 family.

CONCLUSION

FDRs of patients with CeD have 3-fold higher risk of developing autoimmune thyroid disorders and associated thyroid dysfunction. Therefore, it is advisable for early screening of FDRs for CeD and associated thyroid autoimmune through screening measures.

Autoantibodies in the Extraintestinal Manifestations of Celiac Disease

Increased antibody reactivity towards self-antigens is often indicative of a disruption of homeostatic immune pathways in the body. In celiac disease, an autoimmune enteropathy triggered by the ingestion of gluten from wheat and related cereals in genetically predisposed individuals, autoantibody reactivity to transglutaminase 2 is reflective of the pathogenic role of the enzyme in driving the associated inflammatory immune response. Autoantibody reactivity to transglutaminase 2 closely corresponds with the gluten intake and clinical presentation in affected patients, serving as a highly useful biomarker in the diagnosis of celiac disease. In addition to gastrointestinal symptoms, celiac disease is associated with a number of extraintestinal manifestations, including those affecting skin, bones, and the nervous system. Investigations of these manifestations in celiac disease have identified a number of associated immune abnormalities, including B cell reactivity towards various autoantigens, such as transglutaminase 3, transglutaminase 6, synapsin I, gangliosides, and collagen. Clinical relevance, pathogenic potential, mechanism of development, and diagnostic and prognostic value of the various identified autoantibody reactivities continue to be subjects of investigation and will be reviewed here.

Increased Incidence of Thyroid Disease in Patients with Celiac Disease: A Systematic Review and Meta-Analysis

The prevalence of thyroid disease is likely increased among individuals with celiac disease (CD). In addition, exposure to gluten-free treatment may be associated with a risk of thyroid disease, but this association remains controversial. A systematic review was performed to evaluate the association between thyroid disease and CD. The articles were obtained from the PubMed, Web of Science, Embase, and Chinese WanFang bibliographical databases for the period up to May 2016. The results were analysed in a meta-analysis with odds ratios (ORs) and corresponding 95% confidence intervals (95% CIs). There were 13 articles in this meta-analysis, including 15629 CD cases and 79342 controls. Overall, the prevalence of thyroid disease in patients with CD was significantly increased compared with that in the control groups (OR 3.08, 95% CI 2.67-3.56, P<0.001). Moreover, there was no significant difference in the OR between the gluten-treated and untreated groups (OR 1.08, 95% CI 0.61-1.92, P = 0.786). The results of our meta-analysis support the hypothesis that the prevalence of thyroid disease in patients with CD is increased compared with that in controls, which suggests that CD patients should be screened for thyroid disease. The effect of gluten-free treatment on thyroid disease needs further investigation.

Hepatitis C virus infection and thyroid autoimmune disorders: A model of interactions between the host and the environment

The hepatitis C virus (HCV) infection is an important public health problem and it is associated with hepatic and extrahepatic manifestations. Autoimmune thyroid diseases are common in HCV infected patients and the standard interferon-based treatment is associated with an increase of the immune-mediated thyroid damage. Recent evidence in the literature analyzed critical points of the mechanisms of thyroid damage, focusing on the balance between the two sides of the interaction: The environment (virus infection with potential cross-reaction) and the host (susceptibility genes with consistent immune response). The spectrum of antiviral treatment for chronic HCV infection is rapidly expanding for the development of dual o triple therapy. The availability of interferon-free combined treatment with direct antiviral agents for HCV is very promising, in order to ameliorate the patient compliance and to reduce the development of thyroid autoimmunity.

Relevance, pathogenesis and clinical implications of thyroid disorders in children with celiac disease

Celiac disease is a frequent chronic inflammatory small bowel disease which may present itself with associated autoimmune comorbidities. Among these comorbidities, thyroid disorders show a significant prevalence; even in the pediatric population. However, the exact epidemiology and clinical significance of such alterations are yet to be fully elucidated. The most updated guidelines do not currently offer any specific support. Focusing on the pediatric population, we will review the recent available literature that we believe might be helpful in advancing the clinician's knowledge-base regarding this issue. We also discuss which, to our knowledge, are the key pathophysiologic concepts behind the association between these two entities. Finally, we offer our own clinical perspective, recommending routine laboratory thyroid screening, possibly followed by an echographic thyroid evaluation as we believe such an approach to be appropriate when caring for children with celiac disease.

Unrecognized Celiac Disease in Children Presenting for Rheumatology Evaluation

BACKGROUND AND OBJECTIVES

Current clinical guidelines do not consider patients with rheumatic conditions to be at high risk for celiac disease (CD) despite numerous reported associations between the two in adults and children. The objective of this study was to evaluate the prevalence of CD among patients presenting for pediatric rheumatology evaluation.

METHODS

A total of 2125 patients presenting for initial evaluation by the Division of Pediatric Rheumatology at the Hospital for Special Surgery between June 2006 and December 2013 were screened for CD as a part of the standard initial serologic evaluation. The charts of these patients were evaluated retrospectively at the end of this period.

RESULTS

36 patients (30 girls, 6 boys, mean age 9.4 ± 4.3 years, range 2-16 years) received a diagnosis of CD after serologic testing and evaluation by pediatric gastroenterology. Eight additional patients with known diagnoses of CD presented during this time period. The total prevalence of CD over this 6.5-year period was 2.0%. The most common presenting complaints among patients diagnosed with CD were myalgias, arthralgias, and rash. Less frequently, patients reported gastrointestinal complaints including abdominal pain, nausea, and diarrhea. All patients reported improvement or complete resolution of their musculoskeletal symptoms after initiation of a gluten-free diet.

CONCLUSIONS

This study identified 36 new cases of CD among children presenting for rheumatology evaluation, for an overall prevalence rate of 2.0%. The majority of patients who ultimately received a diagnosis of CD presented with extraintestinal manifestations. These results underscore the importance of screening children presenting for rheumatology evaluation for CD.

US perspective on gluten-related diseases

The incidence of allergy and autoimmune disease in the US and other industrialized nations is increasing, and gluten-related disorders are no exception. The US has documented a profound rise in celiac disease that cannot be fully explained by improved serological techniques or better recognition by physicians. Non-celiac gluten sensitivity, a condition only recently recognized by the medical community, has become a commonly diagnosed entity. Proteins, including gluten are increasingly being identified as a source of wheat allergy. Although the gluten free diet represents a safe and effective treatment for these conditions, there is still much to be learned about the development of gluten-related disorders and the apparent increase in incidence within the US. In this article, we present a review of current knowledge on the epidemiology of gluten-related disorders within a global context, with a focus on diagnostic trends and the evaluation of potential risk factors.

Guillain-Barre Syndrome Associated with Gastric Cancer: Paraneoplastic Syndrome or Immunological Disorder?

Guillain-Barre syndrome is a rare clinical entity classified as an ascending muscle paralysis led by autonomic nervous dysfunction due to autoimmune damage of peripheral nerves. Paraneoplastic Guillain-Barre syndrome has been described in association with some kinds of tumors (B-cell Lymphoma and small cell lung cancer). We describe the case of a 74-year-old woman affected by gastric adenocarcinoma, treated with surgery and adjuvant chemotherapy, who developed simultaneously skin cancer relapse and severe Guillain-Barre syndrome. Although the timing of clinical presentation suggests a paraneoplastic origin, other interesting features were present in this patient such as familial and personal anamnesis for autoimmune disease, HCV infection, and neurotoxic chemotherapy. According to literature, we investigated different pathogenetic hypothesis. According to the poorness of data, further investigations are necessary to establish a relationship between Guillain-Barre syndrome and gastric cancer.

Two faces of an illness: ankylosing spondylitis developed after rheumatoid arthritis

A szerzők egy 35 éves nőbeteg kórtörténetét ismertetik, akinél 29 éves korában szeronegatív rheumatoid arthritist igazoltak a reumatológiai osztályon. A betegség remisszióját sikeres graviditás követte, majd két évvel később kizárólag axiális tüneteket mutató spondylarthritist diagnosztizáltak. A major hisztokompatibilitási komplex vizsgálata során a hagyományos szerológiai módszerekkel a HLA B27 spondylarthritis ankylopoeticára jellemző, valamint HLA DR1 rheumatoid arthritisre jellemző haplotípust mutattak ki. A HLA DRB-polimorfizmus vizsgálata során a rheumatoid arthritis létrejöttében és kórlefolyásában szerepet játszó HLA DR B1 0101 allél jelenlétét igazolták. A betegben tehát ritka kombinációként a spondylarthritis ankylopoetica és a rheumatoid arthritis létrejöttében is szerepet játszó HLA-formáció egyaránt megtalálható volt.

Systematic review: The evidence base for long-term management of coeliac disease

BACKGROUND

While gluten-free diet is an effective treatment for coeliac disease, the need for and goals of long-term management of patients are poorly defined.

AIM

To review systematically the complications and associations of coeliac disease, to identify potential risk factors, to define ways of assessing risk factors and to provide a strategy for management.

METHODS

Review of medical literature from 1975.

RESULTS

There is an increasing list of potential complications and/or conditions associated with coeliac disease, in particular, autoimmune disease, malignancy and bone disease. Risk factors that may predict or influence long-term outcomes include genetic susceptibility, environmental factors predominantly gluten ingestion, persistent small intestinal inflammation/injury and nutritional deficiencies. Genotyping of patients is yet to have an established clinical role in long-term management. Assessment of adherence to the gluten-free diet largely relies upon skilled dietary history, but the ultimate test is duodenal histopathology, which is the only currently established means of assessing healing. Symptoms, serology or other non-invasive means are poor predictors of healing and the likelihood of complications.

CONCLUSION

Evidence (albeit limited) that adherence to a gluten-free diet and mucosal healing prevent and/or ameliorate complications indicates that a planned long-term strategy for follow-up is essential.

Autoantibodies in celiac disease

Autoantibody production is an important feature of many autoimmune disorders, signifying a breakdown of immune tolerance to self-antigens. In celiac disease, an autoimmune enteropathy with multiple extra-intestinal manifestations, autoantibody reactivity to transglutaminase 2 (TG2) has been shown to closely correlate with the acute phase of the disease. It serves as a specific and sensitive marker of celiac disease, and is highly useful in aiding diagnosis and follow-up. Immune reactivity to other autoantigens, including transglutaminase 3, actin, ganglioside, collagen, calreticulin and zonulin, among others, has also been reported in celiac disease. The clinical significance of these antibodies is not known, although some may be associated with specific clinical presentations or extra-intestinal manifestations of celiac disease. This review examines the presence of anti-TG2 and other autoantibodies in celiac disease, discussing their diagnostic value, their potential role in disease pathogenesis and current hypotheses that explain how their release may be triggered.

Celiac disease and autoimmune thyroid disease

Celiac disease (CD) or gluten sensitive enteropathy is relatively common in western populations with prevalence around 1%. With the recent availability of sensitive and specific serological testing, many patients who are either asymptomatic or have subtle symptoms can be shown to have CD. Patients with CD have modest increases in risks of malignancy and mortality compared to controls. The mortality among CD patients who comply poorly with a gluten-free diet is greater than in compliant patients. The pattern of presentation of CD has altered over the past three decades. Many cases are now detected in adulthood during investigation of problems as diverse as anemia, osteoporosis, autoimmune disorders, unexplained neurological syndromes, infertility and chronic hypertransaminasemia of uncertain cause. Among autoimmune disorders, increased prevalence of CD has been found in patients with autoimmune thyroid disease, type 1 diabetes mellitus, autoimmune liver diseases and inflammatory bowel disease. Prevalence of CD was noted to be 1% to 19% in patients with type 1 diabetes mellitus, 2% to 5% in autoimmune thyroid disorders and 3% to 7% in primary biliary cirrhosis in prospective studies. Conversely, there is also an increased prevalence of immune based disorders among patients with CD. The pathogenesis of co-existent autoimmune thyroid disease and CD is not known, but these conditions share similar HLA haplotypes and are associated with the gene encoding cytotoxic T-lymphocyte-associated antigen-4. Screening high risk patients for CD, such as those with autoimmune diseases, is a reasonable strategy given the increased prevalence. Treatment of CD with a gluten-free diet should reduce the recognized complications of this disease and provide benefits in both general health and perhaps life expectancy. It also improves glycemic control in patients with type 1 diabetes mellitus and enhances the absorption of medications for associated hypothyroidism and osteoporosis. It probably does not change the natural history of associated autoimmune disorders.

Gastrointestinal manifestations of endocrine disease

The hormonal interactions among the systems throughout the body are not fully understood; many vague clinical symptoms may in fact be manifestations of underlying endocrine diseases. The aim of the following review is to discuss gastrointestinal manifestations of surgically correctable endocrine diseases, focusing on abnormalities of thyroid function, cancer and finally autoimmune diseases. We also review manifestations of pancreatic endocrine tumors, and multiple endocrine neoplasia.

Prevalence of coeliac disease in Italian patients affected by Addison's disease

OBJECTIVE

It is well known that coeliac disease is associated with autoimmune endocrine diseases, such as autoimmune thyroid disease and insulin-dependent diabetes mellitus. Recently, coeliac disease has been shown in approximately 10% of patients with autoimmune Addison's disease. Addison's disease is the most common cause of primary adrenocortical insufficiency and it shares several clinical features with coeliac disease. Although hyperpigmentation and hypotension are the most specific signs, gastrointestinal symptoms are common and can be the first complaints of the patients. The aim of our study was to investigate the prevalence of coeliac disease in Italian patients with Addison's disease.

MATERIAL AND METHODS

Seventeen consecutive patients affected by Addison's disease (14 F, mean age 53.9 years, range 26-79 years) were enrolled in the study. Eleven of them were affected by Addison's disease associated with autoimmune thyroid disease and/or insulin-dependent diabetes mellitus; the other 6 patients were suffering from isolated Addison's disease. Diagnosis had been performed at the age of 40.5 years (range 23-55). Steroid treatment had already been started in 16 of the patients. Endomysial antibodies were tested in all of them and a duodenal biopsy was taken in those found to be positive for antiendomysial antibody (EMA).

RESULTS

One out of 17 patients was found to be EMA positive. Duodenal biopsy confirmed the diagnosis of coeliac disease by showing subtotal villous atrophy.

CONCLUSIONS

Although we studied only a small sample, our preliminary results confirmed that Addison's disease is associated with coeliac disease, being present in 5.9% of patients with Addison's disease. Since the symptoms can be similar and treatment of Addison's disease can mask coeliac disease, this association should always be actively investigated.

Association of celiac disease with connective tissue diseases and autoimmune diseases of the digestive tract

Celiac disease (CD) is an autoimmune enteropathy triggered by the ingestion of gluten in susceptible individuals, and is one of the most frequent genetically based diseases, with a prevalence of 1:200 in the general population. The association between CD and connective tissue diseases (CTD) and autoimmune diseases of the digestive tract (DT) has been described in several case reports but in few extensive studies, with varying prevalence. A high rate of false positive results were observed when low specific tests, such as the anti-gliadin and the guinea pig tissue transglutaminase (tTG) antibody assays were used. In a study of 400 patients with CTD and 218 with autoimmune DT disease, tested for IgA and IgG anti-tTG using the more specific human recombinant antigen, 12 cases (1.9%) of anti-tTG antibody positivity were found, but only 2 (0.3%) were confirmed as affected by CD following small bowel biopsy. Most of the patients testing false positive had primary biliary cirrhosis. In this short review we describe the association between CD and CTD, inflammatory bowel disease and primary biliary cirrhosis, with special emphasis on the diagnostic accuracy of CD antibody assays.

Celiac disease and HLA DQ in patients with IgA nephropathy

OBJECTIVES

Despite some reports on an association between celiac disease and IgA nephropathy, the evidence is still sparse. Celiac disease is strongly associated with the HLA DQ2 and DQ8 haplotypes, which might explain the potential risk of patients to contract various autoimmune conditions. In this study, we sought to establish how common celiac disease is in patients with IgA nephropathy, and whether the possible association can be explained by similar HLA DQ status.

METHODS

A total of 223 consecutive adult patients with IgA nephropathy were studied; 95 cadaver organ transplant donors served as controls for HLA DQ analysis. The diagnosis of celiac disease was based on small bowel mucosal biopsy. All known celiac cases were recorded, and eligible patients (n = 168) underwent serological screening for celiac disease as well as HLA DQ2 and DQ8 analysis. Screening methods were serum endomysium and tissue transglutaminase antibodies; patients who tested positive underwent mucosal biopsy.

RESULTS

Eight patients (3.6%, 95% CI = 1.6-7.0%) with IgA nephropathy were found to have celiac disease; three of them were identified by serological screening. All celiac cases had the HLA DQ2 or DQ8 haplotype, but these were not more common in patients with IgA nephropathy than in controls. As many as 14% of HLA DQ2 positive patients with IgA nephropathy had celiac disease. Gluten-free diet had no apparent influence on the course of nephropathy.

CONCLUSIONS

Although there is no increase in celiac-type HLA DQ, patients with IgA nephropathy carry a risk of contracting celiac disease. It can be hypothesized that the increased intestinal permeability in IgA nephropathy may predispose genetically susceptible patients to celiac disease.

Endocrinological disorders and celiac disease

Celiac disease is a permanent intolerance to dietary gluten. Its well known features are abdominal symptoms, malabsorption of nutrients, and small-bowel mucosal inflammation with villous atrophy, which recover on a gluten-free diet. Diagnosis is challenging in that patients often suffer from subtle, if any, symptoms. The risk of clinically silent celiac disease is increased in various autoimmune conditions. The endocrinologist, especially, should maintain high suspicion and alertness to celiac disease, which is to be found in 2-5% of patients with insulin-dependent diabetes mellitus or autoimmune thyroid disease. Patients with multiple endocrine disorders, Addison's disease, alopecia, or hypophysitis may also have concomitant celiac disease. Similar heredity and proneness to autoimmune conditions are considered to be explanations for these associations. A gluten-free diet is essential to prevent celiac complications such as anemia, osteoporosis, and infertility. The diet may also be beneficial in the treatment of the underlying endocrinological disease; prolonged gluten exposure may even contribute to the development of autoimmune diseases. The diagnosis of celiac disease requires endoscopic biopsy, but serological screening with antiendomysial and antitissue transglutaminase antibody assays is an easy method for preliminary case finding. Celiac disease will be increasingly detected provided the close association with autoimmune endocrinological diseases is recognized.

Modulation of immune function by dietary lectins in rheumatoid arthritis

Despite the almost universal clinical observation that inflammation of the gut is frequently associated with inflammation of the joints and vice versa, the nature of this relationship remains elusive. In the present review, we provide evidence for how the interaction of dietary lectins with enterocytes and lymphocytes may facilitate the translocation of both dietary and gut-derived pathogenic antigens to peripheral tissues, which in turn causes persistent peripheral antigenic stimulation. In genetically susceptible individuals, this antigenic stimulation may ultimately result in the expression of overt rheumatoid arthritis (RA) via molecular mimicry, a process whereby foreign peptides, similar in structure to endogenous peptides, may cause antibodies or T-lymphocytes to cross-react with both foreign and endogenous peptides and thereby break immunological tolerance. By eliminating dietary elements, particularly lectins, which adversely influence both enterocyte and lymphocyte structure and function, it is proposed that the peripheral antigenic stimulus (both pathogenic and dietary) will be reduced and thereby result in a diminution of disease symptoms in certain patients with RA.

Celiac disease and markers of celiac disease latency in patients with primary Sjögren's syndrome

OBJECTIVE

Many autoimmune diseases occur concomitantly with celiac disease. We investigated prospectively the occurrence of celiac disease and small-bowel mucosal inflammation in patients with primary Sjögren's syndrome.

METHODS

A total of 34 patients with primary Sjögren's syndrome and 28 controls underwent small bowel biopsy. Villous morphology, jejunal intraepithelial lymphocytes, and mucosal HLA-DR were evaluated and DQA and DQB alleles, serum antiendomysial, and antigliadin antibodies were examined.

RESULTS

Five (14.7%) of 34 Sjögren's syndrome patients were found to have celiac disease. The density of jejunal intraepithelial gammadelta+ T cells was increased in all celiac and in four nonceliac patients. All celiac patients, 69% of nonceliac Sjögren's syndrome patients, and 11% of control subjects showed enhanced HLA-DR expression (p < 0.001). HLA DQ2 was present in 19 (56%) patients with Sjögren's syndrome, including all five with celiac disease.

CONCLUSIONS

The findings show a close association between Sjögren's syndrome and celiac disease. Even among nonceliac patients with primary Sjögren's syndrome, an ongoing inflammation is often present in the small bowel mucosa.

Application of murine T-T hybridoma cells to in vitro potency assay of human synthetic peptide vaccines

Recently, it has been shown that the immunization of mice with an 18 amino acid synthetic peptide corresponding to the third hypervariable region of MHC class II beta chain can induce a specific antibody response against MHC class II molecules, and can be utilized in the prevention and treatment of experimental allergic encephalomyelitis (EAE) [Proc. Natl. Acad. Sci. 1994, 91, 8005-8009]. Based on this finding, a chemically-modified synthetic peptide with the amino acid sequence corresponding to residues of beta 57-76 from human HLA-DR4Dw4 (DR4/1 peptide) is being clinically investigated for the treatment of rheumatoid arthritis in human. The present study describes the development of a novel in vitro potency assay for human HLA-DR4/1 peptide using cloned murine T-T hybridoma cells. Several mouse strains were immunized with the DR4/1 peptide and their lymph node T cell proliferation was measured in the presence of syngeneic APCs and the DR4/1 peptide. T cells isolated from the peptide primed-B10. PL mouse strain, which showed the highest recall response in this assay, were fused with BW5147 lymphoma cells to generate DR4/1 peptide-specific T-T hybridoma clones. Cloned hybridoma cells were characterized for peptide specificity and MHC class II restriction, and used to monitor the biological activity of various DR4/1 peptide preparations. The potency of peptide batches were assessed by measuring the IL-2 secretion of cloned T-T hybridoma cells upon TCR engagement in an antigen-specific manner. The quantitative detection of IL-2 was performed by measuring [3H]thymidine incorporation of HT-2 cells or directly by ELISA. These results demonstrate that peptide-specific murine T-T hybridoma clones can be successfully utilized to monitor biological activity of synthetic peptides by measuring T cell-mediated immunological responses. Development of such in vitro potency assay for synthetic peptides may have broad applications for vaccines related to immunological disorders.

Functionally active recombinant alpha and beta chain-peptide complexes of human major histocompatibility class II molecules

Major histocompatibility (MHC) class II molecules are cell surface heterodimeric (alphabeta) glycoproteins that display processed antigens to T cell receptors (TCRs) of CD4-positive T cells. The present study describes that individual recombinant alpha and beta chains of human MHC class II molecules lacking the transmembrane region (alpha-Tm and beta-Tm) are capable of binding antigenic peptide and that these complexes of chain-peptide are recognized by TCRs to induce antigen-specific apoptosis in restricted T cells. The alpha-Tm and the beta-Tm of human HLA-DR2 (DRB5*0101) were cloned, expressed in Escherichia coli, and purified in large scale by conventional chromatographic methods. The in vitro binding of an immunodominant epitope from the myelin basic protein (MBP-(83-102)Y83) to purified DR2 alpha-Tm and DR2 beta-Tm was demonstrated with biotinylated and fluoresceinated MBP-(83-102)Y83 peptide. The specificity of the MBP-(83-102)Y83 peptide binding to both DR2 alpha-Tm and DR2 beta-Tm was demonstrated in a competitive peptide binding assay. When exposed to a transformed T cell clone (SS8T) restricted to DR2(DRB5*0101) and MBP-(84-102) peptide, complexes of DR2 alpha-Tm and DR2 beta-Tm with MBP-(83-102)Y83 peptide were able to specifically recognize TCRs as measured by the increase in gamma-interferon (gamma-IFN) cytokine. Such recognition of TCRs by soluble alpha-MBP-(83-102)Y83 and beta-MBP-(83-102)Y83 complexes led to the induction of antigen-specific apoptosis in SS8T cells as measured by double fluorescence flow cytometry and electron microscopy. These results provide the first evidence that soluble complexes of antigenic peptide and individual chains of human MHC class II molecules lacking the transmembrane region can recognize TCRs and induce antigen-specific apoptosis in T cells. Since activated CD4-positive T cells are involved in pathogenesis of various autoimmune diseases, the apoptosis triggered by individual soluble chain-peptide complexes has significant potential for eliminating autoreactive T cells.

Transplant-associated autoimmune mechanisms in human hepatitis C virus infection

In order to define factors which are important for the development of hepatitis C virus (HCV) infection and disease in transplant patients, we examined the role of class II MHC antigen restriction in viral antigen presentation to support a hypothesis of the association of this disease with an autoimmune pathogenesis. A greater degree of histocompatibility match between these donors and their HCV-negative recipients was associated with a greater predisposition to recipient HCV liver disease (ALT elevation) posttransplant. The HCV carrier state could be identified with significant amplification of autologous mixed lymphocyte reactivity (AMLR) in both long-term hemodialysis and long-term renal transplant patients, but the AMLR was absent in end-stage liver disease patients with HCV-associated cirrhosis and was insignificantly elevated in these patients with persistent infection in the first 2 years after a new liver was transplanted. There was also a moderate reduction in autologous reactivity as well as serum HCV titers among renal transplant patients who displayed biochemical evidence of chronic liver disease as opposed to those who did not. This appeared later in the course of the disease. HCV RNA could be detected in peripheral blood mononuclear cells (PBMC) of only a portion of HCV-infected renal transplant patients and these showed significantly higher autologous reactivity. In contrast, despite the fact that observations were earlier after de novo liver transplantation, HCV RNA (i.e., earlier in the course of a new or recurrent disease process) was found in PBMC of all liver transplant recipients tested. The AMLR of noninfected laboratory volunteers could be amplified by preincubating their stimulating cells (APCs) with enriched HCV possibly in immune complex (pHCV-IC). This amplification appeared only with specific combinations of HCV strains with HLA DR serotypes. In addition, HCV-primed T cells could be generated to the virus which displayed accelerated activation kinetics. Liver infiltrating lymphocytes extracted from HCV-positive end-stage diseased livers had significantly higher proliferative and cytotoxic reactivity to autologous (HCV-infected) hepatocytes than the extracted lymphocytes responding to autologous hepatocytes from HCV-negative livers. These findings offer evidence of dynamic autoimmune mechanisms in the spectrum of progression of HCV disease and may help to predict the effect of intervention at various intervals in this progression in organ transplant recipients.

Abnormal lymphocyte subsets in Kuwaiti patients with type-1 insulin-dependent diabetes mellitus and their first-degree relatives

Circulating lymphocyte subset imbalance is associated with type-1 insulin-dependent diabetes mellitus (IDDM). To examine the imbalance in these immunoregulatory cells in Kuwaitis with type-1 diabetes and their first-degree relatives we analysed T-lymphocyte subsets and HLA-DR expression (activation) in 18 IDDM patients with a family history of IDDM and 18 non-diabetic first-degree relatives of the IDDM patients. Both IDDM patients and their first-degree relatives showed a mild lymphopenia. Total T lymphocytes, CD3+ cells, in IDDM patients and their first-degree relatives were reduced compared to control subjects (P < 0.001). Total B lymphocytes, CD19+ cells, was increased in IDDM patients (P = 0.001), but was comparable to controls in IDDM patients' first-degree relatives. No quantitative abnormality was demonstrated in CD4+ cells in IDDM patients; however, these cells were higher in their first-degree relatives (P = 0.0089). Suppressor T lymphocytes, CD8+ cells, in first-degree relatives and controls were not significantly different; however, these cells were significantly reduced in IDDM patients (P = 0.001). The ratio of CD4+/CD8+ cells was higher in IDDM patients and their first-degree relatives compared to controls (P = 0.0007 and 0.0103, respectively). Activated T lymphocytes, HLA-DR+ CD3+ cells, were significantly increased in IDDM patients and their first-degree relatives. HLA-DR3 was the most common antigen found in IDDM patients (77% vs. 20% in controls, P = 0.00021). The second most common antigen was HLA-DR4 (55% vs. 24% in controls, P = 0.0566). However, no relationship was found in the levels of CD3+, CD4+ or CD8+ cells in patients possessing either DR3 or DR4. These results suggest that T-lymphocyte subset imbalance not only characterizes the cellular autoimmunity in the pathogenesis of IDDM but may also be significant in early pre-diabetic stages in those with a family history of IDDM.

Twin studies in auto-immune disease

Immune-mediated diseases affect up to 5% of the population and are a major cause of morbidity and mortality. These diseases can be organ specific, such as insulin-dependent diabetes (IDDM) and non-organ specific, such as Rheumatoid Arthritis (RA). Identical and non-identical twins have been used to establish whether these diseases are determined by genetic or environmental factors. The results of these studies have been collated in a new section of the Mendel Institute in Rome. Diseases included in these studies included IDDM, RA, Systemic Lupus Erythematosus (SLE), Multiple Sclerosis (MS) and Myasthenia. Striking differences in concordance rates between identical and non-identical twins in all these studies suggest that genetic factors are important in causing these diseases. All the diseases are known to be associated with HLA genes on chromosome 6 which may account for some or all of the genetic susceptibility. However, in the majority of pairs the affected twin has an unaffected co-twin. These observations suggest that non-genetically determined factors, probably environmental factors and not somatic mutations, are critical. The study of unaffected co-twins, who are at high disease-risk, has allowed the identification of changes which precede and predict the clinical disease. The immune-mediated destruction in many of these diseases is probably caused by T-lymphocytes. Twin studies have shown the importance of genetic factors in determining T-cell responses. Identical twins should, therefore, provide the perfect test bed to assess the role of T-cells in immune-mediated diseases.

MHC class I and autoimmune diabetes

The cause of failed self tolerance, resulting in autoimmunity is unknown, although genetic linkage to genes within the MHC class II region have been well described. We present evidence that failed self tolerance in autoimmune diabetes appears to be secondary to an antigen presenting cell defect; the diabetic antigen presenting cells fail to deliver fragments of endogenous antigens to the cell surface in the groove of MHC class I. In the diabetic NOD mouse model, this correlates with a rare allele at the Tap-1 locus, a gene that controls proper MHC class I assembly by providing fragments of endogenous peptides into the endoplasmic reticulum. We propose that MHC class I presentation of self peptides may represent a normal pathway for tolerance induction and interruption of this important class I function from any cause, including the MHC class II-linked Tap-1 and Tap-2 genes, which may result in autoreactivity.