DETERMINATION OF ANTI GAD65 AUTOANTIBODIES WITH AN ELISA BEFORE AND AFTER STANDARDIZATION WITH THE NEW INTERNATIONAL REFERENCE SERUM

The serum of a stiff-man syndrome patient was declared international G AD reference standard at the ''1st GAD Antibody Workshop'' held at the ''12th International Immunology and Diabetes Workshop'' in Orlando, F lorida, USA 1993. A comparative study was performed with 123 diabetic and non-diabetic patients to evaluate whether standardization of this reference serum had changed the properties of a commercially available ELISA assay. All samples classified positive with the old test were c onfirmed with the new assay. Four additional samples with high ''norma l'' values became positive with the new test. One of them was a contro l person having a family history of diabetes and genetic loci DR4/DR11 . These findings might implicate a higher risk for the developement of IDDM. The new standardization and adaptation of the ELISA seems to ha ve influenced the sensitivity of the test positively.