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

References1. Tisch, R., et al,Induction of GAD65-specific regulatory T cells inhibitsongoing autoimmune diabetes in nonobese diabeticmice.Diabetes, 47:894, 1998.2. Tisch, R., et al,Induction of GAD65-specific Th2 cells and preventionof autoimmune diabetes at late stages of disease developmentis epitope dependent.J. Immunol. 163:1178, 1999.3. Tisch, R., et al,Antigen-specific mediated suppression of ß cell autoimmunityby plasmid DNA vaccination.J. Immunol. 166:2122, 2001.4. Seifarth, C., et al,. More stringent conditions of plasmidDNA vaccination are required to protect graftedversus endogenous islets in nonobese diabetic mice.J. Immunol. (in press). 2003.Roland Tisch, Professor in Microbiology andImmunology at the University of NorthCarolina. Currently, the laboratory is studyingType I diabetes, an autoimmune diseasecharacterized by the T cell mediateddestruction of insulin produ-cing beta cells.The non-obese diabetic (NOD) mouse, aspontaneous animal model for Type I diabetesis being utilized to eluci-date the keymolecular and cellular events involved in thediabetogenic response.GAD65 and the Immunoregulationof Autoimmune DiabetesORoland Tischur group has used GAD65as a model ß cell autoantigenfor the purpose ofdeveloping strategies ofantigen-specific basedimmunotherapy, and definingevents involved in the breakdown of selftolerancewithin the T cell compartment in nonobesediabetic (NOD) mice. As in Man, GAD65-specific reactivity can be detected in NOD miceearly in the diabetogenic response, suggesting akey role for this ß cell autoantigen in both murineand human Type 1 diabetes (T1D).The goal of antigen-specific based immunotherapyis to selectively prevent and/or suppress pathologicalautoimmunity without hindering the“normal” function of the immune system. In anumber of models of autoimmunity includingT1D, prevention and/or treatment of disease istypically accomplished through induction of socalledimmunoregulatory T cells, of which thereappear to be a number of “types” exhibitingvarious physical and functional properties. Weand others have found that administration ofGAD65 protein or peptides via different routes toyoung NOD mice can prevent initiation of thediabetogenic response. More importantly, administrationof GAD65 can prevent the onset ofovert diabetes even at late stages of preclinicalT1D in NOD mice (1-4). This latter scenario isreflective of a clinical setting in which prediabeticindividuals exhibiting ongoing ß cell autoimmunitywould be considered for some form of intervention.Furthermore, we have recently foundthat GAD65 vaccination can also be effectivelyapplied to induce islet graft tolerance. Specifically,islets transplanted into diabetic NOD mice areprotected long-term via administration of geneticvaccines encoding a portion of GAD65 and cytokinesknown to promote T cells with immunoregulatoryfunction. One key characteristic of theprotection mediated by GAD65 administration isthat infiltration of T cells and other immune cellsinto the islets is efficiently blocked regardless ofthe stage of disease progression. This propertyappears to be unique to GAD65 since protectionmediated by administration of other ß cell autoantigensis usually marked by continued infiltrationof the islets, especially when the diabetogenicresponse is ongoing at the time of treatment.Currently, there is a need to further define theproperties of GAD65-specific immunoregulatoryT cells. For example, different “types” of T cellsexhibiting distinct as well as overlapping immunoregulatoryfunctions appear to be induced byadministration of GAD65 under the appropriateconditions. Therefore, the general immunotherapeuticefficacy of GAD65 vaccination may reflectthe relative number and “variety” of immunoregulatoryT cells elicited by treatment.Indeed, GAD65-specific T cells may “normally”regulate the progression of T1D. We have establishedNOD mice in which a significant frequencyof developing T cells express a “transgenic” T cellreceptor (TCR) specific for a peptide derivedfrom GAD65. T cells expressing the transgenicTCR are efficiently deleted through mechanismsthat prevent the development of autoreactive Tcells and maintain tolerance to self-proteins suchas GAD65. Interestingly, T1D is exacerbated inthese transgenic NOD mice. This finding suggeststhat deletion of T cells expressing the transgenicTCR results in the loss of GAD65-specific T cellswhich regulate the diabetogenic response. In thecontext of immunotherapy, GAD65 vaccinationmay in part lead to the expansion of this pool ofimmunoregulatory T cells. The task at hand is todetermine whether findings regarding the role ofGAD65-specific immunoregulatory T cells inNOD mice can be extrapolated to diabetic individualsand/or those at high risk and exploited forthe purpose of immunotherapy.page 24 dmccad june 2003