Epitope-specific glutamic acid decarboxylase-65 autoantibodies in intravenous immunoglobulin preparations

Intravenous immunoglobulin (IVIG) has been used to treat many autoimmune di sorders including Stiff-Man Syndrome (SMS). SMS is a neurological disorder associated with an immune-mediated deficiency of gamma-aminobutyric acid (G ABA) due to autoantibodies against the GABA synthesizing enzyme glutamic ac id decarboxylase-65 (GAD65). GAD65 autoantibodies are present among 1-2% of healthy individuals. It can therefore not be excluded that GAD65 autoantib odies may be present in IVIG, which is prepared from multiple blood donors. We report here that GAD65 but not IA-2 autoantibodies were present in comm ercial IVIG preparations. The presence of autoantibodies may affect the out come of IVIG treatment and screening commercial preparations of IVIG for GA D65 autoantibodies is therefore recommended before treating patients.