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

References1. Baekkeskov, S., et al,Autoantibodies in newly diagnosed diabetic childrenimmunoprecipitate specific human pancreatic islet cellproteins.Nature 298, 167-169 (1982).2. Baekkeskov, S., et al,Antibodies to a Mr 64,000 human islet cell antigen precedethe clinical onset of insulin-dependent diabetes. J.Clin. Invest. 79, 926-934 (1987).3. Baekkeskov, S., et al,Revelation of specificity of 64k autoantibodies in IDDMserums by high-resolution 2D-gel electrophoresis.Unambiguous identification of 64k target antigen.Diabetes 38, 1133-1141 (1989).4. Christgau, S., et al,Pancreatic ß-cells express two autoantigenic forms of glutamicacid decarboxylase, a 65kDa hydrophilic form anda 64kDa amphiphilic form which can be both membrane-boundand soluble.J. Biol. Chem. 266, 21257-21264 (1991).5. Baekkeskov, S., et al,Identification of the 64k autoantigen in insulin-dependentdiabetes as the GABA-synthesizing enzyme glutamicacid decarboxylase.Nature 347, 151-156 (1990).6. Kim, J., et al,Higher autoantibody levels and recognition of a linearN-terminal epitope in the autoantigen GAD65 distinguishstiff-man syndrome from insulin dependent diabetes.J. Exp. Med. 180, 595-606 (1994).7. Kanaani, J., et al,A combination of three distinct trafficking signals mediatesaxonal targeting and presynaptic clustering of GAD65.J. Cell Biol. 158, 1229-1238. (2002).8. 8. Kash, S. F., et al,Increased anxiety and altered responses to anxiolytics inmice deficient in the 65 kDa isoform of glutamic aciddecarboxylase.Proc. Natl. Acad. Sci. 96, 1698-1703 (1999).9. Shi, Y., et al,Increased expression of glutamic acid decarboxylase andGABA in pancreatic b-cells impairs glucose-stimulatedinsulin secretion at a step proximal to membrane depolarization.Am. J. Physiol. Endocrinol. Metab. 279, 684-694, (2000).10. Schwartz, H., et al,High resolution epitope mapping and structural modelingof human glutamic acid decarboxylase 65.J. Mol. Biol. 287, 983-999 (1999).11. Jaume, J. C., et al,Suppressive effect of GAD65-specific autoimmune Blymphocytes on processing of T cell determinants locatedwithin the antibody epitope.J. Immunology 169, 665-672, (2002).Contributions tothe GAD65 FieldISteinunn Baekkeskovn the 1960’’s and 1970’s several investigatorsdiscovered evidence to show thatinsulin dependent diabetes mellitus(Type 1 diabetes or T1D) is an autoimmmunedisease characterized by circulatingautoantibodies to the β cell in humanpancreatic islets and infiltration of lymphocytesinto the islets. However, the target antigen of thisautoimmunity was completely unknown, when Ijoined the Hagedorn Laboratory in Copenhagen inlate 1979 to work with Åke Lernmark. Usingexpertise I had gained in studying target antigensin trypanosomes, I developed a method that alloweda very sensitive detection of human β cellproteins that bound to circulating autoantibodiesin the blood of patients. To our surprise, we discoveredthat autoantibodies in the blood from 8 outof 10 diabetic children bound to the same protein,a 64kD antigen from human islets while none of10 healthy children recognized this protein. Thiswas the very first indication that there was a specifictarget antigen in the autoimmune response inT1D (1). We then showed that the autoantibodiesto the 64kD protein can be present many yearsbefore clinical onset of T1D (2), suggesting thatthese autoantibodies can be used as a sensitivemarker to identify individuals at risk of developingT1D. Also, in all autoimmune diseases the targetantigen is of critical importance because of itspotential to be used to prevent the autoimmunedisease. Having established my own laboratoryfirst at the Hagedorn Research Laboratory andlater at the University of California, San Francisco,we developed amethod for partiallypurifyingthe 64kD protein(2-3). Wecharacterizedimportantbiochemicaland biophysicalparameters ofthe antigen (2-4) in a painstakingeffort thatculminated inits identificationas theSteinunn Baekkeskov,Ph.D., is a Professor atthe University ofCalifornia. Baekkeskov´scurrent research projectsfocus on four mainareas: i) structure,function, and cell biologyof GAD65, IA-2 and glima 38; ii) characterizationof disease specific B-cell epitopesin GAD65, and IA2, and the temporalpattern of their recognition during early andlate phases of §-cell destruction; iii) characterizationof autoimmune T cell epitopes inGAD65 and IA2, and how they can be used toinduce apoptosis in autoimmune T cells duringthe preclinical phase to prevent disease; iv)and mechanisms of transplantation tolerance,and development of methods to preventallo- as well as autoimmune destruction ofislet cell transplants.smaller isoform of the GABA-synthesizing enzymeglutamic acid decarboxylase or GAD65 (5). Theidentification of a component of the 64kD autoantigenas GAD65 transformed the field ofImmunology of Diabetes, because it became possibleto use recombinant protein for developmentof autoantibody assays and for studies of autoimmunemechanisms in the NOD mouse. A fewyears later, a second component of the 64kD autoantigen,left behind by our purification method,was identified as the protein IA-2 by Michaelpage 18 dmccad june 2003