B-cell function and islet cell and other organ-specific autoantibodies in relatives to insulin-dependent diabetic patients

Relation between antibodies to islet cell antigens, other autoantigens and cow's milk proteins in diabetic children and unaffected siblings at the clinical manifestation of IDDM. The Childhood Diabetes in Finland Study Group

The relation between islet cell specific antibodies, other autoantibodies and antibodies to cow's milk proteins was studied in IDDM and pre-IDDM by analysing islet cell antibodies (ICA), insulin autoantibodies (IAA), anti-nuclear (ANA), anti-reticulin class IgA [ARA(IgA)], smooth muscle, anti-mitochondria, parietal cell (PCA), adrenal and thyroid antibodies and antibodies to cow's milk formula (CMF), beta-lactoglobulin (BLG) and bovine serum albumin (BSA) in a population based study with more than 650 children with newly diagnosed IDDM and more than 550 initially non-diabetic siblings. After adjustment for age a weak association was seen in the diabetic children between IAA and ANA but none between ICA and autoantibodies directed against the other organ-specific or non-organ-specific antigens. There was no significant difference in cow's milk antibodies between diabetic children with and without ICA or IAA. The siblings with ICA had higher CMF (IgA and IgM) antibody levels and BLG (IgA) antibody levels than the remaining siblings, but no such differences were found when comparing IAA-positive and negative siblings. Siblings positive for ICA had PCA more often than did the ICA-negative siblings, whereas siblings positive for both ICA and PCA had increased levels of antibodies against CMF, BLG and BSA. These findings indicate that the humoral islet cell-associated autoimmunity characteristic of recent-onset childhood IDDM is clearly restricted to the islet cells and not directly related to signs of other organ-specific or non-organ-specific autoimmunity. The observation of increased levels of antibodies to cow's milk proteins in siblings positive for ICA suggests that the immune response to cow's milk proteins may be related to the progressive autoimmune process resulting in beta-cell destruction and ultimately in the clinical manifestation of IDDM. Gastrointestinal autoimmune mechanisms may play a role in the pathogenesis of IDDM, and the association observed between combined ICA and PCA positivity and increased levels of antibodies to cow's milk proteins in the siblings implies that there may be an enhanced transfer of nutritional antigens across the gut barrier in these subjects.

Islet cell antibodies and fasting C-peptide predict insulin requirement at diagnosis of diabetes mellitus

The differential diagnosis between Type 1 (insulin-dependent) and Type 2 (non-insulin-dependent) diabetes is complicated since no specific markers are available for either disease. In this study, 244 consecutive patients were diagnosed with diabetes mellitus during two years in Malmö (230,000 inhabitants), corresponding to an incidence rate of 53.100,000(-1).year-1. Age, body mass index, HbA1c, C-peptide, and levels of islet cell antibodies were determined at the clinical onset, and related to the classification at diagnosis and at follow-up (n = 233) after a median time of 31 (range 1-49) months. After diagnosis, 42 of 244 (17%) were started on insulin while 202 of 244 (83%) were not. Islet cell antibodies were present in 25 of 42 (60%), and in 18 of 183 (10%), respectively. In the non-insulin treated group, patients with islet cell antibodies had lower body mass index (p less than 0.001), higher HbA1c (p less than 0.004), and lower C-peptide (p less than 0.001) than patients without. At follow-up, 11 of 18 (61%) islet cell positive patients were changed to insulin treatment, as were six other patients. Insulin was discontinued in five initially insulin-treated but islet cell antibody negative patients. The sensitivity, specificity and predictive value for insulin treatment at follow-up were for islet cell antibody positivity; 72%, 96% and 84%, respectively, and for low C-peptide value; 60%, 96%, and 80%, respectively. Islet cell antibodies and low C-peptide at diagnosis of diabetes mellitus are concluded to be useful markers to predict insulin dependence.

Islet cell and other organ-specific autoantibodies in all children developing type 1 (insulin-dependent) diabetes mellitus in Sweden during one year and in matched control children

The majority (about 90%) of children developing Type 1 (insulin-dependent) diabetes mellitus do not have a first-degree relative with the disease. Nearly all (389/405, 96%) children (0-14 years) in Sweden, who developed diabetes during one year, were therefore studied to compare islet cell, thyroid peroxidase, thyroglobulin, and gastric H+, K+-ATPase antibodies with 321 age, sex, and geographically matched, but non-related, control children. Islet cell (cytoplasmic) antibodies were found in 81% (316/389) of the patients and in 3% (9/321) of the control children (p less than 0.001). The median islet cell antibody levels were 70 (range 3-8200) Juvenile Diabetes Foundation (JDF) Units in the islet cell antibody positive patients, and 27 (range 17-1200) JDF Units in the control children (NS). Autoantibodies against thyroid peroxidase (8%), thyroglobulin (6%), and gastric H+, K+-ATPase (3%) were all increased in the patients compared with the control children, being 2% (p less than 0.001), 2% (p less than 0.01), and 0.3% (p less than 0.01), respectively. During an observation time of 20-34 months, two of the nine islet cell antibody positive control children developed Type 1 diabetes, after 8 and 25 months respectively, while the others remained healthy and became islet cell antibody negative. None of the islet cell antibody negative control children developed diabetes during the same time of observation. This first investigation of an unselected population of diabetic children and matched control children shows: that islet cell antibodies are strongly associated with newly diagnosed childhood diabetes, that other autoantibodies are more frequent among diabetic children than control children, and that the frequency of islet cell antibodies in the background population of children is higher than previously documented, and could also be transient, underlining that factors additional to islet cell antibodies are necessary for the later development of Type 1 diabetes.

The Swedish childhood diabetes study--results from a nine year case register and a one year case-referent study indicating that type 1 (insulin-dependent) diabetes mellitus is associated with both type 2 (non-insulin-dependent) diabetes mellitus and autoimmune disorders

From July 1, 1977 to July 1, 1986, 3,503 incident cases of Type 1 (insulin-dependent) diabetes mellitus were registered in the Swedish childhood diabetes study. Using data from this register and from a case-referent study, including all incident Type 1 diabetic children in Sweden during one year and, for each patient, two referent children matched according to age, sex and county, we have studied the associations between Type 1 diabetes and familial Type 1 and Type 2 (non-insulin-dependent) diabetes, thyroid, adrenal, allergic, rheumatic, heart and bowel disease. The mean annual incidence per 100,000 during the nine year period was 25.1 for boys and 23.5 for girls. In 8.5% of the patients, one parent had Type 1 diabetes, 73% of whom were fathers. Fifty-six of the patients (1.7%) had a parent with Type 2 diabetes. The prevalence of parental Type 1 diabetes tended to be higher in patients with younger age at onset; whereas, the opposite was found for patients with parental Type 2 diabetes. In the case-referent study, the age-adjusted odds ratio for Type 1 diabetes when a first and/or second degree relative had Type 1 diabetes was 5.5 (95% confidence limits 4.0-7.7), and in accordance with the findings of the case register, the odds ratio tended to be highest in patients with the youngest age at onset. Season at onset of the patients was not associated with parental Type 1 diabetes. The odds ratio for Type 1 diabetes was significantly increased 3.3 (95% confidence limits: 2.3-4.6) when Type 2 diabetes was reported in relatives (three generations).(ABSTRACT TRUNCATED AT 250 WORDS)

Immunological aspects of diabetes mellitus: prospects for pharmacological modification

It is now well known that insulin-dependent diabetes is a chronic progressive autoimmune disease. The prolonged prediabetic phase of progressive beta-cell dysfunction is associated with immunological abnormalities. A prediabetic period is suggested by the appearance of islet cell antibodies, anti-insulin antibodies, and anti-insulin receptor antibodies. The existence of activated T lymphocytes and abnormal T cell subsets are also other markers. There is still no concensus about the use of the immunosuppression superimposed upon conventional insulin therapy in early diagnosed IDDM and the follow-up of the relatives of IDDM patients who share the genetic predisposition and serological markers for the risk of future onset of IDDM. Treatment in the prodromal period cannot be justified because a link between the disease and early markers such as ICA has not been established with certainty (Diabetes Research Program NIH, 1983). Many immunopharmacological manipulations were reported to be effective in animal models. However, most of them are not readily applied to human subjects. Moreover, IDDM patients are now believed to be heterogeneous, with a complex genetic background. HLA-DR, and more recently DQ, are closely related to the genetic predisposition to IDDM but those genes are not themselves diabetogenic. The contribution of autoimmunity does not appear to be uniform, and in some cases, the contribution of virus is considered more important. There is a lack of a marker for the future onset of IDDM. ICA and ICSA were found after mumps infection, but the existence of those autoantibodies and even the co-existence of HLA-DR3 do not always indicate the future trend to insulin dependency. More precise markers will be disclosed through the biochemical analysis of the target antigens on pancreatic beta-cell for islet antibodies and effector T cells. Much safer and more effective immunopharmacological treatment will be developed through animal experimentation using rat and mouse models. The recent development and interest in this field will further facilitate the attainment of the goal for the complete prevention of IDDM.

Islet cell and other organ-specific autoantibodies in healthy first-degree relatives to insulin-dependent

The presence of organ-specific autoantibodies including islet cell surface, cytoplasmic and cytotoxic as well as thyroid-gastric antibodies were determined in healthy, non-diabetic, first-degree relatives to 30 insulin-dependent diabetic (IDDM) children. Thirty healthy families without family-history of diabetes mellitus served as controls. The prevalence of organ-specific autoantibodies among the healthy members in the diabetic families was increased compared to the control families (p less than 0.005). Islet cell cytoplasmic antibodies were only detected in diabetes families, since 23% (7/30) of the probands and 7% (2/31) of the siblings were positive and all others negative. Organ-specific autoantibodies were associated with HLA DR3 only in the diabetes families (p less than 0.025) while autoantibody positive members in the control families were associated with HLA B7 (p less than 0.01). This study suggests that childhood IDDM occurs in families with an increased prevalence of organ-specific autoantibodies.

Immunological aspects of type 1 and 2 diabetes mellitus

IDDM occurs predominantly among individuals being class II antigen HLA-DR 3 and/or 4 positive, while NIDDM is not associated with HLA-D. Although the HLA-DR 3 or 4 specificities are prerequisites for IDDM to develop, their high frequencies (about 60%) in the background population preclude tissue typing as a predictive test, underlined by the observation that less than 50% of monozygotic twins are concordant for IDDM. The presence of a number of immune abnormalities argues that the causes of IDDM may be sought in an altered immune reaction against antigens present in the pancreatic B cells and/or in the environment. The majority of IDDM patients of short duration show both cellular and humoral autoimmunity against the pancreatic B cells. Similar phenomena may be observed in patients initially diagnosed as NIDDM and treated with oral hypoglycemic agents. It has been speculated that these patients have a retarded form of IDDM. It is possible that the combination of specific Class II antigen molecule(s) and an invading antigen (virus, bacterium, chemical etc.) presented to the immune system triggers the formation of effector cells such as B lymphocytes and cytotoxic T lymphocytes which also cross-react with the pancreatic B cells. Multiple exposures to this or related antigens throughout several years may eventually lead a sufficient loss of pancreatic B cells to cause insulin dependence.