RESUMEN
Natural development of diabetes in nonobese diabetic (NOD) mice requires both CD4 and CD8 T cells. Transgenic NOD mice carrying alphabeta TCR genes from a class I MHC (Kd)-restricted, pancreatic beta cell Ag-specific T cell clone develop diabetes significantly faster than nontransgenic NOD mice. In these TCR transgenic mice, a large fraction of T cells express both transgene derived and endogenous TCR beta chains. Only T cells expressing two TCR showed reactivity to the islet Ag. Development of diabetogenic T cells is inhibited in mice with no endogenous TCR expression due to the SCID mutation. These results demonstrate that the expression of two TCRs is necessary for the autoreactive diabetogenic T cells to escape thymic negative selection in the NOD mouse. Further analysis with MHC congenic NOD mice revealed that diabetes development in the class I MHC-restricted islet Ag-specific TCR transgenic mice is still dependent on the presence of the homozygosity of the NOD MHC class II I-Ag7.
Asunto(s)
Linfocitos T CD8-positivos/metabolismo , Linfocitos T CD8-positivos/patología , Diabetes Mellitus Tipo 1/genética , Diabetes Mellitus Tipo 1/inmunología , Receptores de Antígenos de Linfocitos T alfa-beta/genética , Timo/inmunología , Timo/metabolismo , Alelos , Animales , Autoantígenos/inmunología , Linfocitos T CD8-positivos/inmunología , Diferenciación Celular/genética , Diferenciación Celular/inmunología , Diabetes Mellitus Tipo 1/etiología , Diabetes Mellitus Tipo 1/patología , Epítopos de Linfocito T/inmunología , Femenino , Regulación de la Expresión Génica/inmunología , Genes MHC Clase II/fisiología , Genes Codificadores de la Cadena beta de los Receptores de Linfocito T , Islotes Pancreáticos/inmunología , Activación de Linfocitos/genética , Ratones , Ratones Endogámicos NOD , Ratones SCID , Ratones Transgénicos , Receptores de Antígenos de Linfocitos T alfa-beta/biosíntesis , Timo/patología , Transgenes/inmunologíaRESUMEN
Nonobese diabetic (NOD) mice carrying a segment of chromosome flanking the disrupted IFN-gamma receptor gene from original 129 ES cells are resistant to development of diabetes. However, extended backcrossing of this mouse line to the NOD mouse resulted in a segregation of the IFN-gammaR-deficient genotype from the diabetes-resistant phenotype. These results indicate that the protection of NOD mice from the development of diabetes is not directly linked to the defective IFN-gamma receptor gene but, rather, is influenced by the presence of a diabetes-resistant gene(s) closely linked to the IFN-gammaR loci derived from the 129 mouse strain.
Asunto(s)
Diabetes Mellitus Tipo 1/genética , Diabetes Mellitus Tipo 1/prevención & control , Ligamiento Genético/inmunología , Predisposición Genética a la Enfermedad/genética , Interferón gamma , Receptores de Interferón/genética , Traslado Adoptivo , Animales , Diabetes Mellitus Tipo 1/inmunología , Diabetes Mellitus Tipo 1/patología , Femenino , Marcadores Genéticos/inmunología , Predisposición Genética a la Enfermedad/etiología , Genotipo , Antígenos de Histocompatibilidad Clase I/biosíntesis , Inmunidad Innata/genética , Interferón gamma/metabolismo , Interferón gamma/farmacología , Islotes Pancreáticos/patología , Macrófagos Peritoneales/inmunología , Macrófagos Peritoneales/metabolismo , Ratones , Ratones Endogámicos NOD , Ratones Noqueados , Receptores de Interferón/biosíntesis , Receptor de Interferón gammaRESUMEN
The diabetes-susceptible class II MHC genes (in human and mouse) share unique nonaspartic acid residues at position 57 of the class II beta-chain. Transgenic expression of a mutant I-A(g7), substituting histidine and serine at position 56 and 57 of beta-chain with proline and aspartic acid (I-A(g7)PD), respectively, inhibits diabetes development in the nonobese diabetic mouse model. Here, we demonstrate that immature thymocytes expressing a diabetogenic islet Ag-specific transgenic TCR are positively selected by I-A(g7)PD class II MHC to give rise to mature CD4+ T cells. However, splenic APCs expressing the same I-A(g7)PD fail to present pancreatic islet Ag to mature T cells bearing this diabetogenic TCR. These results indicate that nonaspartic acid residues at position 57 of class II MHC beta-chain is important for diabetogenic CD4+ T cell activation in the periphery but is not essential for the formation of a diabetogenic T cell repertoire in the thymus.
Asunto(s)
Enfermedades Autoinmunes/inmunología , Linfocitos T CD4-Positivos/inmunología , Supresión Clonal , Diabetes Mellitus Tipo 1/inmunología , Antígenos de Histocompatibilidad Clase II/genética , Islotes Pancreáticos/inmunología , Activación de Linfocitos , Linfocitos T Citotóxicos/inmunología , Timo/inmunología , Sustitución de Aminoácidos , Animales , Presentación de Antígeno , Codón/genética , ADN Complementario/genética , Antígenos de Histocompatibilidad Clase II/inmunología , Islotes Pancreáticos/patología , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos NOD , Ratones SCID , Ratones Transgénicos , Mutación Puntual , Regiones Promotoras Genéticas , Quimera por Radiación , Receptores de Antígenos de Linfocitos T/genética , Receptores de Antígenos de Linfocitos T/inmunología , Organismos Libres de Patógenos Específicos , Bazo/patología , Linfocitos T Citotóxicos/patología , Timo/patologíaRESUMEN
Mice infected with murine acquired immunodeficiency syndrome (MAIDS) virus developed lymphoadenopathy and profound immunodeficiency. Concomitantly the expression of endogenous mammary tumor virus (MTV) mRNA increased significantly, especially for the 1.7-kb 3' open reading frame (ORF) mRNA encoding MTV superantigen. B cell lines that are established from MAIDS mice and exhibit superantigen activity also express a high level of 1.7-kb endogenous MTV and mRNA. Infection of a B cell tumor line in vitro with retrovirus containing the cloned MAIDS virus gene induced superantigen activity and this cell line also expressed the 1.7-kb superantigen coding MTV 3' ORF mRNA. These results strongly suggest a link between MAIDS virus infection and the induction of endogenous superantigen activity. This may play an important role in the pathogenesis of the MAIDS virus.
Asunto(s)
Linfocitos/virología , Virus del Tumor Mamario del Ratón/genética , Síndrome de Inmunodeficiencia Adquirida del Murino/virología , Secuencia de Aminoácidos , Animales , Genes gag , Linfoma de Células B/virología , Ratones , Datos de Secuencia Molecular , Sistemas de Lectura Abierta , ARN Mensajero/análisis , Bazo/virología , Superantígenos/análisis , Superantígenos/biosíntesis , Células Tumorales CultivadasRESUMEN
Mice bearing the I-Ag7 class II major histocompatibility complex molecules contain a high number of spontaneous autoreactive T cells, as estimated by limiting-dilution assays. We found this autoreactivity in various strains that bear the I-Ag7 molecule, such as the nonobese diabetic (NOD) mouse strain, which spontaneously develops autoimmune diabetes. However, NOD mice strains that do not express the I-Ag7 molecule, but instead express I-Ab, do not have a high incidence of autoreactive T cells. About 15% of the autoreactive T cells also recognize the I-Ag7 molecule expressed in the T2 line, which is defective in the processing of protein antigens. We interpret this to mean that some of the T cells may interact with class II molecules that are either devoid of peptides or contain a limited peptide content. We also find a high component of autoreactivity among antigen-specific T cell clones. These T cell clones proliferate specifically to protein antigens but also have a high level of reactivity to antigen-presenting cells not pulsed with antigen. Thus, the library of T cell receptors in NOD mice is skewed to autoreactivity, which we speculate is based on the weak peptide-binding properties of I-Ag7 molecules.
Asunto(s)
Autoinmunidad/inmunología , Antígenos de Histocompatibilidad Clase II/inmunología , Ratones Endogámicos NOD/inmunología , Linfocitos T/inmunología , Animales , Ganglios Linfáticos/inmunología , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Ovalbúmina/inmunologíaRESUMEN
Murine acquired immunodeficiency syndrome (MAIDS) is caused by a defective murine leukemia virus. The disease is characterized by abnormal lymphoproliferation, impaired T and B cell function and aberrant regulation of cytokines. Both T and B lymphocytes show activated phenotypes, but undergo apoptotic death with characteristic DNA fragmentation. These results indicate the presence of a continuous activation death pathway of the lymphocytes in MAIDS. Overexpression of the bcl-2 transgene in lymphocytes showed no effect on the apoptotic cell death or on the development of the disease. In contrast, mice carrying mutations in either Fas or Fas ligand exhibited accelerated progression of the disease upon infection with MAIDS virus. These results suggest the involvement of Fas-Fas ligand system in the pathogenesis of MAIDS.
Asunto(s)
Apoptosis/inmunología , Linfocitos B/inmunología , Síndrome de Inmunodeficiencia Adquirida del Murino/inmunología , Linfocitos T/inmunología , Animales , Linfocitos B/patología , Células Cultivadas , Glucano Endo-1,3-beta-D-Glucosidasa/biosíntesis , Inmunofenotipificación , Ligandos , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Síndrome de Inmunodeficiencia Adquirida del Murino/metabolismo , Síndrome de Inmunodeficiencia Adquirida del Murino/patología , Mutación , Linfocitos T/patología , Receptor fas/genética , Receptor fas/inmunologíaRESUMEN
A defective murine leukemia virus is the causative agent of murine acquired immunodeficiency syndrome (MAIDS). We have cloned cDNAs from both virus infected and non-infected cells using the PCR methods with primers corresponding to the franking sequence of the unique p12 gag gene. Sequence analysis of these cDNA clones revealed: (i) the presence of endogenous virus related to MAIDS virus in C57BL/6 mice, (ii) B cell lineage specific expression of endogenous virus and (iii) extensive heterogeneity of MAIDS virus recovered from virus infected cells due to the recombination of the related viruses (defective pathogenic virus, ecotropic virus and endogenous virus). These findings suggest that the creation of virus variants in infected cells may play an important role in virus pathogenesis and escape from immune attack during the development of MAIDS.
Asunto(s)
Productos del Gen gag/genética , Virus de la Leucemia Murina/genética , Síndrome de Inmunodeficiencia Adquirida del Murino/virología , Provirus/genética , Homología de Secuencia de Ácido Nucleico , Animales , Secuencia de Bases , Línea Celular , Transformación Celular Viral/genética , Productos del Gen gag/biosíntesis , Virus de la Leucemia Murina/aislamiento & purificación , Ratones , Ratones Endogámicos C57BL , Datos de Secuencia Molecular , Síndrome de Inmunodeficiencia Adquirida del Murino/genética , Provirus/aislamiento & purificación , ARN Mensajero/biosíntesisRESUMEN
Infection of susceptible C57BL/6 mice with defective LP-BM5 murine leukemia virus causes disease termed murine acquired immune deficiency syndrome (MAIDS). The disease is characterized by lymphoadenopathy, hyperimmunoglobulinemia, and immune deficiency in both T and B cell functions. The development of disease requires the presence of mature T cells, especially CD4 T cells, and B cells. It has previously been shown that a B cell tumor line derived from MAIDS mouse stimulated a large fraction of unprimed T cells based on TCR V beta chain expression. This stimulatory activity was assumed to be mediated by a superantigen encoded by MAIDS virus. The stimulation of T cells by viral superantigen was thought to play a role in the development of the disease. To examine the role of T cell reactivity to MAIDS superantigen, we used TCR transgenic mice. There are two distinct T cell populations which can be distinguished based on their TCR expression and function in the TCR transgenic mice, one bearing the transgene derived alpha- and beta-chain TCR that is nonreactive to MAIDS superantigen and the other bearing an endogenous alpha- but transgene-derived beta-chain TCR that is reactive to superantigen. Unlike T cells found in noninfected TCR transgenic mice, anergic T cells expanding in virally infected TCR transgenic mice are homogeneous for the TCR phenotype, indicating the presence of a selection of T cells based on their TCR expression. T cell hybridomas established by fusing T cells from virus-infected transgenic mice to thymoma cell line are also anergic. We found mRNA of defective LP-BM5 virus in a majority of T cell hybridomas from virus-infected mice but not from noninfected mice. By using in vitro infection of T cell clones with recombinant virus containing LP-BM5 MAIDS virus gag gene, we have demonstrated that virus infection directly abrogated the Ag-specific reactivity of T cells. The establishment of anergic T cell hybridomas and the in vitro infection of T cells with recombinant viruses would be a useful tool in the analysis of biochemical and molecular mechanisms of T cell dysfunction in MAIDS.
Asunto(s)
Síndrome de Inmunodeficiencia Adquirida del Murino/inmunología , Linfocitos T/inmunología , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Cartilla de ADN/genética , ADN Viral/genética , Productos del Gen gag/genética , Productos del Gen gag/inmunología , Genes gag/genética , Hibridomas/inmunología , Virus de la Leucemia Murina/genética , Virus de la Leucemia Murina/aislamiento & purificación , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Datos de Secuencia Molecular , Síndrome de Inmunodeficiencia Adquirida del Murino/microbiología , Fenotipo , ARN Viral/genética , ARN Viral/aislamiento & purificación , Receptores de Antígenos de Linfocitos T alfa-beta/genética , SuperantígenosRESUMEN
The murine acquired immunodeficiency syndrome (MAIDS) is induced by a defective murine leukemia virus and has many symptoms similar to those found in patients infected with the human immunodeficiency virus. The presence of both B cells and CD4+ T cells is critical for the development of the disease. Furthermore, a Th2 cytokine response dominates during the progression of the disease. When interleukin-4 (IL-4)-deficient mice that are defective in Th2 cytokine responses were infected, there was no lethality, and the development of the T cell abnormalities associated with MAIDS was delayed. These data suggest that IL-4 or a Th2 response is involved in the development of retrovirus-induced immunodeficiency in mice.
Asunto(s)
Interleucina-4/inmunología , Síndrome de Inmunodeficiencia Adquirida del Murino/inmunología , Linfocitos T Colaboradores-Inductores/inmunología , Animales , Secuencia de Bases , Cartilla de ADN , Productos del Gen gag/genética , Inmunidad Innata , Interleucina-2/biosíntesis , Interleucina-4/biosíntesis , Interleucina-4/deficiencia , Interleucina-4/genética , Virus de la Leucemia Murina/genética , Activación de Linfocitos , Ratones , Ratones Endogámicos C57BL , Ratones Endogámicos , Datos de Secuencia Molecular , ARN Mensajero/análisis , ARN Mensajero/genética , ARN Viral/análisis , ARN Viral/genéticaRESUMEN
A B cell line, B6-1710, expressing murine AIDS virus superantigen stimulates T cell hybridomas derived from a Ld-specific CTL clone to produce IL-2 regardless of their CD4/CD8 phenotype. However, B6-1710 cell did not stimulate the original CTL clone, L3, in either proliferation or cytolytic assays. Both B6-1710 and Ld+ P815 cells stimulated a significant Ca2+ influx in the T cell hybridomas. In contrast, only P815 stimulated tyrosine phosphorylation of a 19-kDa protein in the T cell hybridoma. The addition of the nonspecific protein kinase C activator PMA restored the proliferative response of L3 cells to B6-1710. PMA did not induce the lysis of B6-1710 cells by L3. These results suggest that murine AIDS virus encoded superantigen elicits a TCR-mediated signal different from that caused by nominal Ag. This different signaling by viral superantigen may be important for the development of viral pathogenesis in vivo.