RESUMEN
The present study examined mechanisms of tolerance for T cell receptor gamma/delta (TCR-gamma/delta) cells. Using a transgenic (Tg) model, we demonstrate that although alloantigen (Ag)-specific TCR-gamma/delta cells are deleted in the thymus and spleen of Ag-bearing mice, intraepithelial lymphocytes (IELs) expressing normal levels of the Tg TCR were present. However, Tg+ IELs from Ag-bearing mice were unresponsive to activation. Furthermore, self-reactive Tg+ IELs decreased in number over time. Thus, in epithelial tissue, Tg TCR-gamma/delta cells are eliminated subsequent to and most likely as a result of the induction of clonal anergy.
Asunto(s)
Tolerancia Inmunológica , Receptores de Antígenos de Linfocitos T/inmunología , Linfocitos T/inmunología , Animales , Células Presentadoras de Antígenos/inmunología , Células Cultivadas , Cruzamientos Genéticos , Femenino , Antígenos H-2/inmunología , Isoantígenos/inmunología , Activación de Linfocitos , Linfocinas/biosíntesis , Masculino , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Ratones Transgénicos , Bazo/inmunología , Timo/inmunologíaRESUMEN
We expressed the synaptic vesicle proteins SV2, synaptotagmin, and synaptophysin in CHO fibroblasts to investigate the targeting information contained by each protein. All three proteins entered different cellular compartments. Synaptotagmin was found on the plasma membrane. Both SV2 and synaptophysin were sorted to small intracellular vesicles, but synaptophysin colocalized with early endosomal markers, while SV2 did not. SV2-containing vesicles did not have the same sedimentation characteristics as authentic synaptic vesicles, even though transfected SV2 was sorted from endosomal markers. We also created cell lines expressing both SV2 and synaptotagmin, both synaptotagmin and synaptophysin, and lines expressing all three synaptic vesicle proteins. In all cases, the proteins maintained their distinct compartmentalizations, were not found in the same organelle, and did not created synaptic vesicle-like structures. These results have important implications for models of synaptic vesicle biogenesis.
Asunto(s)
Encéfalo/metabolismo , Proteínas de Unión al Calcio , Glicoproteínas de Membrana/metabolismo , Proteínas del Tejido Nervioso/metabolismo , Vesículas Sinápticas/metabolismo , Sinaptofisina/metabolismo , Animales , Células CHO , Centrifugación por Gradiente de Densidad , Cricetinae , Drosophila/metabolismo , Fibroblastos/metabolismo , Técnica del Anticuerpo Fluorescente , Humanos , Glicoproteínas de Membrana/análisis , Glicoproteínas de Membrana/biosíntesis , Microscopía Electrónica , Microscopía Inmunoelectrónica , Proteínas del Tejido Nervioso/análisis , Proteínas del Tejido Nervioso/biosíntesis , Neurotransmisores/metabolismo , Ratas , Fracciones Subcelulares/metabolismo , Fracciones Subcelulares/ultraestructura , Sinaptofisina/análisis , Sinaptofisina/biosíntesis , Sinaptotagminas , TransfecciónRESUMEN
In the intestine maintenance of self-tolerance may involve tissue-specific self-Ags, APCs, 'second signals', and extrathymic pathways of T cell maturation. These factors combine to create a unique environment where autoimmune tissue destruction is prevented despite local inflammatory influences. In this review we summarize our findings using a TCR-gamma delta transgenic model where self-tolerance was maintained by clonal deletion for cells localizing to peripheral lymphoid tissue and by clonal anergy for cells localizing to the intraepithelial compartments. Several possible explanations exist for these results but in general, these findings have implications for the maintenance of self-tolerance of normal TCR-alpha beta and TCR-gamma delta IELs in epithelial tissues such as the intestine.