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

GAD in GraphsIL-4 (pg/ml)250100755025Immunization with a GAD65/IL-4plasmid DNA vaccine preventsdiabetes in NOD miceB *p=.002untreatedHELGADGAD/IL-40Medium GAD65 HSP60 CPHTisch et al. (2001) Antigen-specific mediatedsuppression of cell autoimmunity by plasmidDNA vaccination.J Immunol 166:2122-2132• Enhanced secretion of IL-4 anddecreased secretion of IFN-γ by Tcells from NOD mice immunized at12 wks old with pDNA encodingGAD65-IgFc and IL-4 and restimulatedwith GAD65.• Vaccination caused a shift in cytokineresponse to GAD65 stimulationOur Story of GAD– Serendipity in SciencePaul Zimmet and Ian MackayOur involvement with the GAD story is one of serendipity. One of us (PZ) was attendinga major international pharmaceutical company advisory board meeting inRome in 1991 and heard the presentation of one of their lead scientists, Dr. BillKnowles. He presented work that he was involved in on islet cell antibodies.This wasjust around the time that GAD had been identified by Baekkeskov as the 64kD antigenthat she had discovered in the 1980’s – a putative key autoantigen in Type 1 diabetes.I told Bill that I was very keen to have access to a method to measure anti-GAD. Over a quiet glass of Chianti, Bill told me that he had purified GAD from pigbrain and was attempting to develop an assay for antibodies but his company was% Islets100β cell-specific expression of GAD isrequired for development of autoimmunediabetes806040200H-AS-GADTg(-)Islets Status4 retracted3 >50%2 25-50%1 >25%0 NormalYoon et al. (1999) Control of autoimmunediabetes in NOD mice by GAD expression orsuppression in β cells Science 284:1183-1190• Islet grafts from transgenic miceexpressing high levels of antisenseGAD65/67 (H-AS-GAD) survivewhen grafted into acutely diabeticNOD mice, while grafts expressingGAD (Tg-) are infiltrated anddestroyed• GAD is the target of autoimmuneattack in diabetesnot all that interested as they were more interested in Type 2 diabetes. I asked himwhether I could have some GAD and he agreed. Knowles became a valued advisorSand collaborator in the next phase of our work.o the GAD came to Melbourneand within a few weeks, the nimblefingers of Dr. Merrill Rowleyin our laboratory resulted in thedevelopment of the first radioimmmunoassay(RIA) for anti-GAD,based on radioiodine labelling of the Knowles’GAD preparation. I was involved with the developmentof a Type 1 Diabetes Register in ourisland state of Tasmania so I was able to quicklyfind samples to test and we demonstrated highlevels in newly diagnosed and long-standing casesof Type 1 diabetes. The results were publishedin Diabetes as the first RIA for anti-GAD.Then again, serendipity came into play. Wewere very interested in the fact that a numberof adults were identified with diabetes that presentedclinically as Type 2 yet their naturalhistory over a period of a year or more was indicativeof insulin dependency. We were awarethat a close friend and colleague, Leif Groop,then in Finland, had undertaken a study someyears previously on a group of these patients andhad demonstrated a positive test for islet cellantibodies. Fortuitously, one of his outstandingyoung researchers, Dr. Tiinamaija Tuomi, hadcome to our laboratory as a visiting researcher.She obtained the serum samples from Groop’sstudy and we were quickly able to measure anti-GAD in these subjects: the frequency of anti-GAD in these adult subjects was very high andappeared to be a better predictor of insulindependency than ICA. Indeed, when vigorouslychallenged by a leading authority on ICA at anAmerican Diabetes Association presentation asto our ability to perform the measurement ofpage 34 dmccad june 2003