Diabetes-Associated Autoantibodies Among Young Diabetes Mellitus Patients in Malaysia

@#Introduction: Diabetes-associated autoantibodies (DAA) is the hallmark of T1DM and LADA which are frequently tested in young diabetes patients. It was noted that up to 10-15% of patients with initial diagnosis of T2DM also exhibit DAA. Regardless of the classification, the presence of DAA suggests an underlying islet autoimmunity which lead to progressive pancreatic β-cell failure. There is limited data reported on DAA in young diabetes patients in Malaysia. This study aims to determine the frequency of DAA positivity and its association with demographic and clinical characteristics among this cohort. Methods: A retrospective study using secondary data obtained from Allergy and Immunology Research Centre, Institute for Medical Research, Malaysia. This study included 194 diabetes patients who were diagnosed before the age of 40 years old and tested for GADA, ICA, IA2A and IAA. Results: From 194 patients, 91 (46.9%) were positive for least one of the following DAA: ICA (79, 40.7%), GADA (61, 31.4%), IA2A (37, 19.1%) and IAA (9, 4.6%). Multiple positivity was higher (73.6%) compared to single positivity. Highest combination of double positivity was ICA+GADA (54, 59.3%) and triple positivity was ICA+GADA+IA2A (25, 27.5%). Simultaneous positivity of four autoantibodies was seen in only one (1.1%) patient. ICA, GADA and IA2A were associated with age group and ethnicity (all p < 0.001). Only IA2A was associated with gender (p = 0.012). Conclusions: GADA, ICA ad IA2A are more significant in young Malaysian diabetes patients. IAA has a very low frequency in this studied population.

Islet cell antigens and autoantigen(s): Monoclonal antibodies and further characterization.

A novel series of murine monoclonal antibodies to islet cells (I-45, I-51, I-52 and I-39) have been generated using human insulinoma homogenate as the immunogen in order to characterize pathogenetically relevant islet cell autoantigen(s). Differentiation antigens recognized by these islet cell monoclonal antibodies displayed varied cytological distribution (pan-islet or peripheral mantle only). Monoclonal antibody I-45 reacted with all endocrine subsets of the pancreatic islet, similar to the reactivity of islet cell autoantibody positive sera from type I diabetes subjects. Preexposure to pH2 abolished the immunoreactivity of the autoantigen; I-45 antigen was also sensitive to low pH. Preexposure to 100° C for 1 h did not significantly alter the immunoreactivity of islet antigens recognized by ICAb positive patient sera and monoclonal antibody 1-39, thus demonstrating the extraordinary heat stability of the corresponding epitopes; those recognized by I-45 were less heat stable. Islet cells were found to share I-45 differentiation antigen(s)/epitope(s) with other neuroendocrine cells, viz. amerior pituitary, adrenal medulla and gut endocrine cells.

Association between islet cell antibody subtypes and secretions of insulin and glucagon / 中华内分泌代谢杂志

Objective To investigate the insulin and glucagon levels in the patients with different islet cell antibody (ICA) subtypes and to explore the pathogenesis of latent autoimmune diabetes of adult (LADA). Methods Subjects were classified by immunohistology and 29 ICA-peripheral-positive DM patients, 28 ICA-diffused-positive DM patients and 17 controls (ICA-negative) were included. Serum glucose, insulin and plasma glucagon were measured at 0, 30, 60, 120 min after standard meal. Results (1) As compared with controls, glucagon in ICA positive groups were higher (both P