Check GAD antibody positivity with the Diamyd anti-GAD RIA plate*

GAD in GraphsA1004 wks of age% Incidence of diabetes% Incidence of diabetes80604020B10001480604018 22 2610 wks of age(n=12)PlasmidsGAD65GAD65-GMCSFcontrol(n=8)(n=13)Vaccination with GAD plasmid DNAprevents diabetes in NOD mice(n=11)PlasmidsGAD65GAD65-GMCSFcontrol20(n=8)(n=7)016 14 20 24 28 32 36Balasa et al, 2001. Vaccination with GAD plasmidDNA protects mice from spontaneousautoimmune diabetes and B7/CD28 costimulationcircumvents that protectionClin Immunol 99:241-252• Mice vaccinated at both 4-5 (A)and 10-11 weeks of age (B) wereprotected from developing diabetesIs GAD All There Is?TBart Roephe discovery of GAD65 as oneof the first islet autoantigens inthe pathogenesis of type 1 diabeteswas a breakthrough thatenabled study of specific autoimmuneresponses. I worked asa postdoc in the laboratory of Steinunn Baekkeskovin San Francisco at the time that the identity ofthe 64,000 kDa target of autoantibodies was unraveledas GAD65. My aim as a T cell immunologistwas to determine T cell autoreactivity to this proteinin humans, and to study whether immunizationof genetically predisposed mice with GAD65led to the induction of insulitis or diabetes. Theresults in these pioneer studies to check for T cellautoimmunity were unexpected since I foundvery few differences between patients and controlsubjects, although in both groups significantresponses were detectable. With few exceptions,this finding turned out to be reproducible bymany colleagues all over the world during the folllowingdecade. My second aim to induce diabetesby immunization with GAD65 was in vain:although very strong immune responses could beinduced in various strains of mice, none of thesedeveloped insulitis or diabetes. The latter observationproved useful for the application of usingGAD65 as an immune modulator rather than asan inducer of pathogenesis. Currently there is consensusthat, immunization with GAD65 delays orprevents diabetes in mice, rather than inducing oraccelerating the disease.For the next step as T cell immunologists, weintroduced GAD65 as a candidate target autoantigenin our immune monitoring of Type 1 diabetespatients receiving islet allografts. Indeed, chronicrecurrent loss of islet allograft function wasaccompanied with increment in T cell autoreactivityto GAD65, even in the absence of increases inantibody titers, while this reactivity was neverobserved in patients successfully transplanted withislets. This clinical trial proved that longitudinalstudies on cellular immune responses to GAD65were informative to determine the clinical fate ofbeta-cells in Type 1 diabetes patients. It proved oftremendous importance to test GAD65 of highpurity to avoid reactivity to contaminants in thepreparation of recombinant GAD65. This was theprime result from the first international workshopon T cell reactivity to islet autoantigens. Eversince, I have used GAD65 produced and purifiedby diamyd as golden standard, since this materialwas of reproducibly high quality and void of toxicor mitogenic contaminants. A second satisfactoryencounter with GAD65 came from studies in arare autoimmune disorder called Stiff-ManSyndrome (SMS) that shares GAD65 with Type 1diabetes as major target autoantigen. One-third ofSMS patients develop Type 1 diabetes. We studieda case of SMS without Type 1 diabetes to understandwhy SMS patients often do not developType 1 diabetes despite phenomenal autoimmunityto this neuroendocrine autoantigen GAD65, inorder to develop immunotherapy for Type 1 diabetesin patients that lost tolerance to this protein.Indeed, the GAD65 reactivity measured in thispage 30 dmccad june 2003