Pancreatic IL-4 expression results in islet-reactive Th2 cells that inhibit diabetogenic lymphocytes in the nonobese diabetic mouse.
When immunological tolerance breaks down, autoimmune destruction of insulin-producing beta cells in the pancreas can cause insulin-dependent diabetes mellitus. We previously showed that transgenic nonobese diabetic (NOD) mice expressing IL-4 in the pancreas (NOD-IL-4 mice) were protected from insulitis and diabetes. Here we have characterized the avoidance of pathological autoimmunity in these mice. The absence of disease did not result from a lack of T cell priming, because T cells responding to dominant islet Ags were present. These islet Ag-specific T cells displayed a Th2 phenotype, indicating that Th2 responses could account for the observed tolerance. Interestingly, islet Ag-specific Th1 T cells were present and found to be functional, because neutralization of the Th2 effector cytokines IL-4 and IL-10 resulted in diabetes. Histological examination revealed that NOD-IL-4 splenocytes inhibited diabetogenic T cells in cotransfer experiments by limiting insulitis and delaying diabetes. Neutralization of IL-4 in this system abrogated the ability of NOD-IL-4 splenocytes to delay the onset of diabetes. These results indicate that IL-4 expressed in the islets does not prevent the generation of pathogenic islet responses but induces islet Ag-specific Th2 T cells that block the action of diabetogenic T cells in the pancreas.
Gallichan
W S
WS
Department of Immunology, The Scripps Research Institute, La Jolla, CA 92037, USA.
Balasa
B
B
Davies
J D
JD
Sarvetnick
N
N
D000818:Animals; D001324:Autoantigens / Q000276:immunology; D016207:Cytokines / Q000096:biosynthesis; D003922:Diabetes Mellitus, Type 1 / Q000235:genetics / Q000276:immunology* / Q000473:pathology / Q000517:prevention & control*; D018984:Epitopes, T-Lymphocyte / Q000235:genetics; D005260:Female; D015333:Gene Rearrangement, beta-Chain T-Cell Antigen Receptor; D005968:Glutamate Decarboxylase / Q000276:immunology; D007108:Immune Tolerance / Q000276:immunology*; D016130:Immunophenotyping; D015847:Interleukin-4 / Q000096:biosynthesis* / Q000235:genetics / Q000502:physiology; D007515:Islets of Langerhans / Q000276:immunology* / Q000473:pathology; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D008822:Mice, Transgenic; D010179:Pancreas / Q000276:immunology* / Q000378:metabolism; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000235:genetics; D013601:T-Lymphocytes / Q000201:enzymology / Q000276:immunology / Q000378:metabolism; D018418:Th2 Cells / Q000276:immunology* / Q000378:metabolism
D001324:Autoantigens; D016207:Cytokines; D018984:Epitopes, T-Lymphocyte; D016693:Receptors, Antigen, T-Cell, alpha-beta; D015847:Interleukin-4; D005968:Glutamate Decarboxylase