Inselzell-Ak ELISA

Insulin-dependent diabetes mellitus (IDDM) or Type I Diabetes is a debilitating chronic disease that impairs production and secretion of the key hormone insulin and alters blood sugar metabolism. Insulin is synthesised and secreted by pancreatic islet cells or islets of Langarhans. The disruption of insulin synthesis is caused by immunological destruction of the islet cells by autoantibodies in IDDM patients. Such abnormalities (autoimmunity) may be genetically inherited and/or triggered by exposure to toxic chemicals, viral infections and various forms of stress. IDDM has a characteristic asymptomatic prediabetic phase that may last up to several years. During this period, the affected individuals exhibit the diminishing early-phase release of insulin in response to an intravenous/oral glucose challenge. In the majority of cases, these individuals carry circulating islet cell autoantibodies (ICA) and/or insulin autoantibodies (IAA). ICA can be detected as early as eight years prior tothe clinical onset of IDDM and thus may serve as an early indicator of the disease or of predisposition to it. Individuals who are ICA-positive may show a progressive loss of the islet cell function as indicated by disruption of the early-phase insulin release. When this early phase insulin release completely stops, clinically overt IDDM develops. ICA are present in 70 % of patients with recent onset of IDDM compared with 0.1 - 0.5 % of the control non-diabetic population. ICA are also detected in first degree relatives of IDDM patients. These individuals comprise the segment of human population who are at a high risk of developing IDDM. Several studies reported that the ICA-positive first degree relatives of IDDM patients subsequently developed diabetes. Other studies also suggested that the presence of serum ICA and IAA is an indicator or the enhanced likelihood to develop IDDM. Therefore, serological detection of ICA may be a powerful tool for early diagnosis of IDDM. The significance of these autoantibodies as markers of IDDM is also illustrated by their presence in nondiabetic individuals who ultimately develop IDDM. Riley, et. al. recently reported that determination of ICA in Type 2 Diabetes patients could identify IDDM prior to the onset of clinical symptoms and predict the need for insulin therapy. Thus, those patients who are initially diagnosed with Type 2 Diabetes and carry serum ICA may deteriorate to insulin dependence. Early detection of circulating ICA is important to identify the individuals in the general population, the siblings and families of IDDM patients who are at a higher risk of developing this disease because of their genetic predisposition to diabetes. At a recent international workshop on ICA, the imminent need for an ELISA test for the determination of islet cell autoimmunity was emphasized. Currently, serum ICA are determined by indirect immunofluorescence and histochemical methods employing frozen unfixed human/primate or rat pancreatic sections as substrates. Despite various attempts to improve and modify this procedure since its original description in 1974,the indirect immunoflourescence/histochemical technique suffers from inherent methodological problems. Standardisation of the technique has proven to be very difficult. The reliability of this "frozen-section" technique is limited by factors such as the variation from one pancreas to another, the inevitable need for unfixed pancreatic tissue and infrequent availability of the suitable tissue. This ICA test is a qualitative ELISA test for in vitro detection of circulating IgG antibodies against pancreatic islet cell antigens.