RESUMEN
To study peripheral tolerance of CD8 T cells to a classically MHC-restricted peptide Ag expressed in hepatocytes, ALB1 transgenic (tg) mice expressing the CTL epitope GP33 of the lymphocytic choriomeningitis virus glycoprotein under control of the mouse albumin promoter were generated. ALB1 mice exclusively expressed the GP33 transgene in the liver and, at a 100- to 1000-fold lower level, in the thymus. TCR-tg mice specific for the GP33 epitope were used to directly follow GP33-specific T cells in vivo. These experiments revealed that 1) thymic expression of the GP33 transgene led to incomplete central deletion of TCR-tg cells; and 2) peripheral TCR-tg cells in ALB1 mice ignored the GP33 transgene expressed in hepatocytes. Ignorance of adoptively transferred TCR-tg cells in ALB1 mice was broken by infection with lymphocytic choriomeningitis virus, leading to induction of hepatitis in ALB1, but not in control, mice. Taken together, we have established a novel model of virus-induced CD8 T cell-mediated autoimmune hepatitis in mice and demonstrate that naive CD8 T cells may ignore Ags expressed in the liver.
Asunto(s)
Antígenos Virales/inmunología , Hepatitis Viral Animal/etiología , Hepatitis Viral Animal/inmunología , Tolerancia Inmunológica , Hígado/inmunología , Hígado/virología , Linfocitos T/inmunología , Proteínas Virales , Traslado Adoptivo , Animales , Antígenos Virales/biosíntesis , Antígenos Virales/genética , Epítopos de Linfocito T/genética , Epítopos de Linfocito T/inmunología , Glicoproteínas/biosíntesis , Glicoproteínas/genética , Hepatitis Viral Animal/genética , Tolerancia Inmunológica/genética , Hígado/metabolismo , Depleción Linfocítica , Coriomeningitis Linfocítica/genética , Coriomeningitis Linfocítica/inmunología , Ratones , Ratones Endogámicos C57BL , Ratones Endogámicos DBA , Ratones Transgénicos , Fragmentos de Péptidos/biosíntesis , Fragmentos de Péptidos/genética , Receptores de Antígenos de Linfocitos T/genética , Linfocitos T/metabolismo , Timo/inmunología , Timo/metabolismo , Transgenes/inmunologíaRESUMEN
In a review of the chest X-rays and medical records of 597 cases of culture- or biopsy-proven pulmonary tuberculosis (PTB; age range 1.5-72 years), seen over a period of 6 years (1991-97), 26 patients had radiographic patterns unusual for PTB. These patterns were mass-like densities simulating neoplasms, chronic lower lobe airspace opacities without adenopathy, mediastinal adenopathy without parenchymal airspace opacities and bronchopleural fistula without other radiographic abnormalities. The most common of these unusual radiographic patterns was mass-like densities, most of which were initially and mistakenly diagnosed as neoplasms. These masses, seen in 11 adult patients, form the basis of this report. Two children aged 1.5 and 2 years also had tuberculous mass densities initially diagnosed as neurogenic tumour and round pneumonia, respectively. They have been excluded from the present series, and form the subject of another report. The masses were lower lobe predominant and were not usually associated with fibro-productive satellite lesions or with calcification or cavitation. In view of the recent resurgence of PTB and the importance of chest X-rays in its diagnosis and management, this rare radiographic pattern needs to be emphasized.
Asunto(s)
Neoplasias Pulmonares/diagnóstico por imagen , Tuberculosis Pulmonar/diagnóstico por imagen , Adulto , Diagnóstico Diferencial , Femenino , Humanos , Masculino , Persona de Mediana Edad , Tomografía Computarizada por Rayos XRESUMEN
We established bone marrow stromal cell lines from a transgenic mouse that harbors a temperature-sensitive mutant of the simian virus 40-derived large T-antigen under the control of a major histocompatibility complex (MHC) I promotor. These cell lines were screened for their ability to induce the formation of osteoclasts in a spleen cell/stromal cell coculture system. By means of this screen, five clones, referred to as marine bone marrow stromal clone 1 (mBMS-B1) mBMS-B2, mBMS-B14, mBMS-B18, and mBMS-B21, were selected for detailed characterization. Cell growth depends on culture conditions, i.e., cells grow at 33 degrees C in the presence of murine interferon-gamma, whereas cell proliferation ceases at 39 degrees C. The phenotype of the cells is also correlated with the culture conditions because the osteoclast inductive capacity is only seen at 39 degrees C, indicating that the cells undergo differentiation when the transforming agent is inactivated. These conditionally immortalized stromal cells can be induced to express a variety of markers that are typical for mature osteoblasts, e.g., alkaline phosphatase activity and expression of functional parathyroid hormone receptor after stimulation with soluble osteogenic protein 1 (sOP-1). mRNA analysis revealed the expression and regulation of osteopontin, osteonectin, and collagen alpha 1(I) as well as the inducibility of osteocalcin upon treatment with sOP-1. The cells have the potential to form mineralized nodules in supplemented medium. We observed expression of vascular cell adhesion molecule-1, which is stimulated upon treatment of the cells with 1 alpha,25-dihydrocholecalciferol after 4 days, indicating the presence of the receptor for this steroid. These cell lines represent a model to study mechanisms and factors involved in osteoblast differentiation.
Asunto(s)
Antígenos Virales de Tumores/genética , Células de la Médula Ósea , Temperatura , Fosfatasa Alcalina/biosíntesis , Animales , Antígenos Virales de Tumores/fisiología , Médula Ósea/enzimología , Médula Ósea/metabolismo , Resorción Ósea/fisiopatología , Calcificación Fisiológica , División Celular , Línea Celular , Ratones , Ratones Transgénicos , Osteoclastos/citología , Osteoclastos/enzimología , Osteoclastos/metabolismo , ARN Mensajero/biosíntesis , Receptores de Hormona Paratiroidea/biosíntesis , Virus 40 de los Simios/genética , Células del Estroma/citología , Molécula 1 de Adhesión Celular Vascular/biosíntesisRESUMEN
To study self reactivity, a transgenic mouse model has been established in which the lymphocytic choriomeningitis virus (LCMV) glycoprotein (gp) is expressed in the beta-islet cells of the pancreas (rat insulin promoter (RIP)-gp). These mice (H-2b) do not spontaneously develop diabetes; however, infection with the LCMV strain WE rapidly induces hyperglycemia. In this study, comparative analysis of H-2k RIP-gp-transgenic animals demonstrated that the haplotype influences the incidence and kinetics of diabetes and alters the requirement for the CD4+ T cell subset. This study also showed that the properties of the virus expressing the self target Ag determined whether hyperglycemia occurred in RIP-gp-transgenic mice. Various LCMV strains were able to induce diabetes in RIP-gp-transgenic animals, whereas infection with a recombinant vaccinia virus expressing LCMV-gp (vacc-gp) did not induce diabetes. However, vacc-gp could induce diabetes in double (RIP-gp/TCR)-transgenic mice, where the majority of CD8+ T cells expressed a receptor specific for LCMV-gp, suggesting that a critical number of self-reactive T cells must be activated to induce disease. Notably, histologic analysis of pancreata taken various days after LCMV or vacc-gp infections indicated that induction of diabetes coincided with an increase in MHC class I expression on the islets of Langerhans. Additional studies with vacc-gp were done to determine other factors that possibly enhance autoimmune attack. Transgenic mice expressing both LCMV-gp and TNF-alpha under the control of the RIP were infected with vacc-gp, and 50% of RIP-gp/TNF-alpha-transgenic animals became hyperglycemic. These data suggest that the increased local lymphocyte traffic as a result of TNF-alpha expression attracts activated gp-specific T cells, enhancing the possibility of hyperglycemia. Collectively, these results demonstrate that the induction of diabetes in this model is influenced by the MHC haplotype, the infectious agent, TNF-alpha expression, the level of MHC class I expression, and the induction of a threshold number of self-reactive CTL.
Asunto(s)
Diabetes Mellitus Experimental/etiología , Antígenos de Histocompatibilidad Clase I/fisiología , Coriomeningitis Linfocítica/inmunología , Factor de Necrosis Tumoral alfa/fisiología , Animales , Antígenos Virales/análisis , Secuencia de Bases , Diabetes Mellitus Experimental/genética , Diabetes Mellitus Experimental/inmunología , Susceptibilidad a Enfermedades , Glicoproteínas/genética , Haplotipos , Antígenos de Histocompatibilidad Clase I/análisis , Coriomeningitis Linfocítica/complicaciones , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Datos de Secuencia Molecular , Ratas , Linfocitos T Colaboradores-Inductores/fisiología , Factor de Necrosis Tumoral alfa/análisis , Virus Vaccinia/inmunologíaRESUMEN
Data are presented showing that MRL/lpr in equilibrium DBA/2 tetraparental (allophenic) chimeras, unlike conventional lpr/lpr----+/lpr bone marrow chimeras, fail to develop graft-vs-host disease; instead they develop full-blown lymphoproliferation and autoantibody formation typical of unmanipulated MRL/lpr mice. The increase in the splenic and especially the lymph node mass is comprised predominantly of MRL/lpr-derived cells and all of the serum IgG2a is MRL/lpr derived. This dominance of MRL/lpr lymphoid activity occurred even in chimeras where greater than 90% of the skin and/or bone marrow cells were of the DBA/2 type. These results demonstrate the failure of the lpr environment to recruit normal B and T cells into the autoimmune process, the inability of normal cells to suppress MRL/lpr disease, and indicate further that the lpr mutation has an intrinsic effect on lymphocytes of both the B and T lineages.
Asunto(s)
Autoinmunidad , Linfocitos B/inmunología , Quimera , Animales , Artritis/inmunología , Tolerancia Inmunológica , Inmunoglobulina G/análisis , Lupus Eritematoso Sistémico/inmunología , Ratones , Ratones Endogámicos DBA , Linfocitos T/inmunologíaRESUMEN
Using mice transgenic for functional, rearranged immunoglobulin heavy and light chain genes, it can be demonstrated that B lymphocytes reactive with cell surface-bound class I MHC antigen can be controlled by clonal elimination. Even low-affinity cell-bound ligands can induce deletion. Deletion can occur in the pre-B to B cell transitional stage or after the B cells exist the bone marrow, depending on where the cells first encounter autoantigen. IgD appears to play no role in protecting cells from deletion. It is argued that defects in B-cell tolerance alone may be sufficient to lead to systemic autoimmunity.
Asunto(s)
Autoantígenos/inmunología , Linfocitos B/inmunología , Animales , Reordenamiento Génico de Cadena Pesada de Linfocito B/inmunología , Reordenamiento Génico de Cadena Ligera de Linfocito B/inmunología , Antígenos de Histocompatibilidad Clase I/inmunología , Tolerancia Inmunológica/inmunología , Ratones , Ratones TransgénicosRESUMEN
To address the mechanisms of tolerance to extrathymic proteins, we have generated transgenic mice expressing the lymphocytic choriomeningitis viral (LCMV) glycoprotein (GP) in the beta islet cells of the pancreas. The fate of LCMV GP-specific T cells was followed by breeding the GP transgenic mice with T cell receptor transgenic mice, specific for LCMV and H-2Db. These studies suggest that "peripheral tolerance" of self-reactive T cells does not involve clonal deletion, clonal anergy, or a decrease in the density of T cell receptors or accessory molecules. Instead, this model indicates that self-reactive cytotoxic T cells may remain functionally unresponsive, owing to a lack of appropriate T cell activation. Infection of transgenic mice with LCMV readily abolishes peripheral unresponsiveness to the self LCMV GP antigen, resulting in a CD8+ T cell-mediated diabetes. These data suggest that similar mechanisms may operate in several so-called "T cell-mediated autoimmune diseases."
Asunto(s)
Antígenos Virales/genética , Diabetes Mellitus Experimental/genética , Glicoproteínas/genética , Tolerancia Inmunológica/genética , Islotes Pancreáticos/microbiología , Virus de la Coriomeningitis Linfocítica/genética , Proteínas Virales/genética , Animales , Antígenos de Diferenciación de Linfocitos T/análisis , Antígenos Virales/análisis , Antígenos CD4/análisis , Antígenos CD8 , Diabetes Mellitus Experimental/inmunología , Diabetes Mellitus Experimental/microbiología , Técnica del Anticuerpo Fluorescente , Vectores Genéticos , Glicoproteínas/análisis , Inmunoterapia Adoptiva , Insulina/genética , Interferón gamma/farmacología , Islotes Pancreáticos/inmunología , Islotes Pancreáticos/patología , Ratones , Ratones Transgénicos , Regiones Promotoras Genéticas , Ratas , Receptores de Antígenos de Linfocitos T/genética , Receptores de Antígenos de Linfocitos T/fisiología , Proteínas Recombinantes , Linfocitos T/inmunología , Proteínas Virales/análisisRESUMEN
Mitotic indices (MIs) and pyknotic (apoptotic) indices (PIs) were assessed in diffuse centrocytic (CC, n = 10), centroblastic/centrocytic (CB/CC, n = 18) and centroblastic (CB, n = 20) malignant non-Hodgkin's lymphomas (NHL). Significant differences were observed. MIs were lowest in CC (median: 0.07%), intermediate in CB/CC (0.18%) and highest in CB (0.43%) NHLs. The PIs exhibited a similar pattern. The PIs of CC (0.11%) and CB/CC (0.17%) NHLs were significantly different from those of CB lymphoma (0.62%). The ratios MI/PI per case, as well as MIs and PIs per case, varied greatly and showed considerable overlapping, thus documenting a marked inter-case and inter-group heterogeneity. MIs tended to loosely correlate with PIs in a non-linear fashion, which raises the question of feedback mechanisms. More information is needed on mitotic time (TM) and apoptotic time (TA), in order to estimate cell doubling time from data on MIs and PIs.
Asunto(s)
Linfoma no Hodgkin/patología , Adulto , Anciano , Humanos , Linfoma de Células B Grandes Difuso/genética , Linfoma de Células B Grandes Difuso/patología , Linfoma no Hodgkin/genética , Microscopía Electrónica , Persona de Mediana Edad , Índice MitóticoRESUMEN
To study the fate of developing B cells in the presence and absence of the autoantigens to which they react, chimeric mice were constructed by injecting bone marrow cells from mice transgenic for rearranged immunoglobulin genes encoding an anti-H-2Kk antibody into irradiated recipients that did or did not express the H-2Kk antigen. In the presence of H-2Kk, the anti-H-2Kk-specific B cells were deleted from the spleen and lymph nodes, whereas in its absence, anti-H-2Kk cells were abundant. B cells bearing a low level of membrane immunoglobulin with the anti-H-2Kk idiotype were found in the bone marrows of H-2Kk recipients, suggesting that clonal deletion of autoreactive cells was occurring in the pre-B-cell to B-cell transitional stage of B-cell development.