Measurement of Anti-38kD Antibody in Korean patients with Insulin-Dependent Diabetes Mellitus by Western Blot Analysis

Kwon, Sun Ja; Lee, Hong Kyu; Kim, Hyeon Kyu

Abstract

BACKGROUND: Insulin-dependent diabetes mellitus (IDDM) is characterized by the destruction of pancreatic b-cells, which is associated with the genetic susceptibility and the production of antibodies to a numter of islet cell antigens(ICA). A possible target antigen, 38kD antigen, was suggested by the proliferation of CD4 T cells frorn a newly diagnosed patient in response to a 38kD polypeptide of the insulin-secretory-granule membrane. Autoantibody to a rat islet cell -protein of 38kD was detectable in the sera of diabetes-prone biobreeding rats by both immunoprecipitation and differential Westem blot analysis. Anti-38kD antibodies were also found to have a 76% sensitivity at the time of diagnosis in diabetic children by immunoprecipitation. In the Asian populations, it has been reported that clinical and immunologic characteristics of IDDM are quite different from those of Caucasians, say low prevalence of ICA. In Korean, there has never been reported the presence of the anti-38kD antibody. Moreover, the time-consuming and laborious nature of assay, such as T-cell proliferation and immuno-precipitation, makes it difficult to use for large population screenings. In the present study, we aimed to evaluate the prevalence of anti-38kD antibody as a immunologic marker in Korean IDDM patients by Western blot analysis. METHODS: Anti-38kD antibody was detected by Western blot analysis using the lysate of rat insulinoma cell line(RINmSF) as an antigenic source. ICA was determined by enzymatic immunohistochemical analysis. The prevalence of anti-38kD antibody and ICA was measured in 38 cases of IDDM, whose mean age at diagnosis and mean duration of IDDM were 25.2+14.2 years and 0.66+0.97 years, respectively. RESULTS: Using Western blot analysis with the lysate fraction of RIN cell, the prevalence of anti-38kD autoantibody(21.1%) in the IDDM paients was significantly higher than that in the control subjects(0.0%, P<0.05). Clinical characteristics between anti-38kD antibody-positive and -negative IDDM patients were not different. In immunohisto-chemical staining, ICA was detected in 18.2% of the IDDM patients, but not in the control subjects. The prevalence of anti-38kD antibody was 21.7%, 28.6% and 12.5% in the patients of less 1 year, 1 year and 2~4 years, respectively, showing no statistically significant difference in the prevalence according to the duration of IDDM. As previously reported, however, the prevalence of ICA decreased with increasing duration of IDDM.
CONCLUSION
These results suggested that the anti-38kD autoantibody is a candidate of autoantibodies for the immunologic markers of Korean IDDM We expect the development of the more methods for the detection of anti-38kD in the future.