Immunization with the larger isoform of mouse glutamic acid decarboxylase (GAD67) prevents autoimmune diabetes in NOD mice.
The 65-kDa isoform of glutamic acid decarboxylase (GAD65) has been implicated in autoimmune diabetes in NOD mice, but the role of the 67-kDa GAD isoform (GAD67) is less clear. We found that immunization of 4-week-old NOD mice with purified recombinant mouse GAD67 prevented or significantly delayed the onset of diabetes. To further explore this phenomenon, we characterized anti-GAD67 immune responses in naive and GAD-immunized NOD mice. Anti-GAD67 antibodies titers were relatively low in naive mice at all ages, but a single immunization with GAD67 at 4 weeks induced high titers of anti-GAD antibodies by 6 weeks of age. In both 4-week-old and diabetic NOD mice, there were significant endogenous T-cell proliferative responses against purified recombinant mouse GAD67. These T-cell proliferative responses were blocked by anti-I-ANOD and anti-CD4 antibodies. To characterize the anti-GAD T-cell responses in the NOD mice, we established T-cell lines and T-cell clones which recognized GAD67, and we used recombinant subfragments of GAD to localize the predominant T-cell epitopes in GAD67. T-cells from naive NOD mice proliferated in response to all GAD subfragments, whereas T-cells from diabetic mice responded primarily to the COOH-terminal 83 amino acids of GAD67. These results suggest that GAD67 is an autoantigen in IDDM and immunization of prediabetic NOD mice with GAD67 can prevent the onset of diabetes.
Elliott
J F
JF
Department of Immunology, University of Alberta, Edmonton, Canada.
Qin
H Y
HY
Bhatti
S
S
Smith
D K
DK
Singh
R K
RK
Dillon
T
T
Lauzon
J
J
Singh
B
B
D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D001324:Autoantigens / Q000276:immunology; D001327:Autoimmune Diseases / Q000517:prevention & control*; D001483:Base Sequence; D015704:CD4 Antigens / Q000276:immunology; D003922:Diabetes Mellitus, Type 1 / Q000276:immunology* / Q000517:prevention & control*; D000939:Epitopes / Q000276:immunology; D005968:Glutamate Decarboxylase / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D006681:HLA-D Antigens / Q000276:immunology; D007114:Immunization; D008213:Lymphocyte Activation; D051379:Mice; D016688:Mice, Inbred NOD; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000276:immunology; D011994:Recombinant Proteins; D013601:T-Lymphocytes / Q000276:immunology
D000906:Antibodies; D001324:Autoantigens; D015704:CD4 Antigens; D000939:Epitopes; D006681:HLA-D Antigens; D010446:Peptide Fragments; D011994:Recombinant Proteins; D005968:Glutamate Decarboxylase