RESUMEN

A hallmark of celiac disease is autoantibodies to transglutaminase 2 (TG2). By visualizing TG2-specific antibodies by antigen staining of affected gut tissue, we identified TG2-specific plasma cells in the lamina propria as well as antibodies in the subepithelial layer, inside the epithelium, and at the brush border. The frequency of TG2-specific plasma cells were found not to correlate with serum antibody titers, suggesting that antibody production at other sites may contribute to serum antibody levels. Upon commencement of a gluten-free diet, the frequency of TG2-specific plasma cells in the lesion dropped dramatically within 6 months, yet some cells remained. The frequency of TG2-specific plasma cells in the celiac lesion is thus dynamically regulated in response to gluten exposure. Laser microdissection of plasma cell patches, followed by antibody gene sequencing, demonstrated that clonal cells were seeded in distinct areas of the mucosa. This was confirmed by immunoglobulin heavy chain repertoire analysis of plasma cells isolated from individual biopsies of two untreated patients, both for TG2-specific and non-TG2-specific cells. Our results shed new light on the processes underlying the B-cell response in celiac disease, and the approach of staining for antigen-specific antibodies should be applicable to other antibody-mediated diseases.

Asunto(s)

Autoanticuerpos/genética , Enfermedad Celíaca/inmunología , Proteínas de Unión al GTP/inmunología , Cadenas Pesadas de Inmunoglobulina/genética , Células Plasmáticas/inmunología , Transglutaminasas/inmunología , Autoanticuerpos/biosíntesis , Biopsia , Enfermedad Celíaca/inducido químicamente , Enfermedad Celíaca/dietoterapia , Enfermedad Celíaca/genética , Recuento de Células , Dieta Sin Gluten , Duodeno/efectos de los fármacos , Duodeno/inmunología , Duodeno/patología , Proteínas de Unión al GTP/genética , Regulación de la Expresión Génica/inmunología , Glútenes/efectos adversos , Humanos , Cadenas Pesadas de Inmunoglobulina/biosíntesis , Mucosa Intestinal/efectos de los fármacos , Mucosa Intestinal/inmunología , Mucosa Intestinal/patología , Captura por Microdisección con Láser , Células Plasmáticas/efectos de los fármacos , Células Plasmáticas/patología , Proteína Glutamina Gamma Glutamiltransferasa 2 , Análisis de Secuencia de ADN , Transglutaminasas/genética

RESUMEN

Graft-versus-host disease (GVHD) is a major cause of morbidity and mortality of allogeneic stem cell transplantation. Strategies to control GVHD while maintaining graft versus leukemia (GVL) include herpes simplex virus thymidine kinase (HSV-tk) gene transduction of donor T cells followed by treatment with ganciclovir (GCV). Alternatively, GVHD and GVL may be mediated by distinct processes. In this regard, whether cytokine polarization occurs and to what degrees various subsets of cytokine-producing T cells mediate GVHD or GVL has been an active area of research using cytokine or cytokine antibody infusion or genetically deficient mice. This study takes a different approach that allows simultaneous investigation into both the mechanisms underlying GVHD reactions and the efficacy of HSV-tk suicide gene-based T-cell deletion. A source of donor T cells, splenocytes from mice transgenic for HSV-tk controlled by elements of either the interleukin-2 (IL-2) or IL-4 promoters (IL-2-tk and IL-4-tk, respectively) was used, thus allowing investigation into the roles of T1 and T2 cells in ongoing GVHD reactions. To assess treatment rather than prevention of GVHD, GCV was started at peak disease. Remarkably, treatment at this late time point rescued mice from the clinical effects of GVHD caused by T cells expressing either transgene. Thus, both T1 and T2 cells play an important role in clinical GVHD in a minor histocompatibility antigen-mismatched setting. In addition, because clinical disease was reversible even at its maximum, these observations provide controlled evidence that this strategy of treating ongoing GVHD could be effective clinically.

Asunto(s)

Modelos Animales de Enfermedad , Enfermedad Injerto contra Huésped/inmunología , Subgrupos Linfocitarios/inmunología , Linfocitos T/inmunología , Animales , Muerte Celular/genética , Citocinas/biosíntesis , Citocinas/metabolismo , Citometría de Flujo , Ganciclovir/uso terapéutico , Enfermedad Injerto contra Huésped/tratamiento farmacológico , Enfermedad Injerto contra Huésped/patología , Efecto Injerto vs Leucemia/inmunología , Hematopoyesis , Células Madre Hematopoyéticas/citología , Células Madre Hematopoyéticas/fisiología , Interleucina-2/genética , Interleucina-4/genética , Masculino , Ratones , Ratones Transgénicos , Regiones Promotoras Genéticas , Simplexvirus/enzimología , Bazo/citología , Timidina Quinasa/genética , Timo/citología , Aumento de Peso

RESUMEN

Intracerebral inoculation with mouse hepatitis virus strain A59 results in viral replication in the CNS and liver. To investigate whether B cells are important for controlling mouse hepatitis virus strain A59 infection, we infected muMT mice who lack membrane-bound IgM and therefore mature B lymphocytes. Infectious virus peaked and was cleared from the livers of muMT and wild-type mice. However, while virus was cleared from the CNS of wild-type mice, virus persisted in the CNS of muMT mice. To determine how B cells mediate viral clearance, we first assessed CD4(+) T cell activation in the absence of B cells as APC. CD4(+) T cells express wild-type levels of CD69 after infection in muMT mice. IFN-gamma production in response to viral Ag in muMT mice was also normal during acute infection, but was decreased 31 days postinfection compared with that in wild-type mice. The role of Ab in viral clearance was also assessed. In wild-type mice plasma cells appeared in the CNS around the time that virus is cleared. The muMT mice that received A59-specific Ab had decreased virus, while mice with B cells deficient in Ab secretion did not clear virus from the CNS. Viral persistence was not detected in FcR or complement knockout mice. These data suggest that clearance of infectious mouse hepatitis virus strain A59 from the CNS requires Ab production and perhaps B cell support of T cells; however, virus is cleared from the liver without the involvement of Abs or B cells.

Asunto(s)

Encéfalo/virología , Anticuerpos Antihepatitis/inmunología , Hígado/virología , Virus de la Hepatitis Murina/inmunología , Animales , Linfocitos B/fisiología , Femenino , Interferón gamma/biosíntesis , Activación de Linfocitos , Ratones , Ratones Endogámicos C57BL , Linfocitos T/inmunología

RESUMEN

When mutations that inactivate molecules that function in the immune system have been crossed to murine lupus strains, the result has generally been a uniform up-regulation or down-regulation of autoimmune disease in the end organs. In the current work we report an interesting dissociation of target organ disease in beta(2)-microglobulin (beta(2)m)-deficient MRL-Fas(lpr) (MRL/lpr) mice: lupus skin lesions are accelerated, whereas nephritis is ameliorated. beta(2)m deficiency affects the expression of classical and nonclassical MHC molecules and thus prevents the normal development of CD8- as well as CD1-dependent NK1(+) T cells. To further define the mechanism by which beta(2)m deficiency accelerates skin disease, we studied CD1-deficient MRL/lpr mice. These mice do not have accelerated skin disease, excluding a CD1 or NK1(+) T cell-dependent mechanism of beta(2)m deficiency. The data indicate that the regulation of systemic disease is not solely governed by regulation of initial activation of autoreactive lymphocytes in secondary lymphoid tissue, as this is equally relevant to renal and skin diseases. Rather, regulation of autoimmunity can also occur at the target organ level, explaining the divergence of disease in skin and kidney in beta(2)m-deficient mice.

Asunto(s)

Antígenos CD1/metabolismo , Lupus Eritematoso Cutáneo/etiología , Nefritis Lúpica/prevención & control , Microglobulina beta-2/deficiencia , Animales , Antígenos CD1/genética , Femenino , Lupus Eritematoso Cutáneo/inmunología , Lupus Eritematoso Cutáneo/patología , Nefritis Lúpica/inmunología , Nefritis Lúpica/patología , Masculino , Ratones , Ratones Endogámicos MRL lpr , Ratones Noqueados , Especificidad de Órganos , Subgrupos de Linfocitos T/inmunología , Microglobulina beta-2/genética

RESUMEN

With the potential spread of bovine spongiform encephalopathy to people as a variant Creutzfeldt-Jakob disease (CJD), it becomes critical to identify cells in the periphery that carry infection. Initial work with scrapie agents suggested that B cells were central vectors for neuroinvasion. Subsequent studies indicated that B cells played an indirect role by promoting the development of follicular dendritic cells (FDCs) that accumulate abnormal prion protein (PrP). The mechanism for the role of FDCs, however, has not been clear. To further dissect potential B cell functions that contribute to neuroinvasion, we inoculated a CJD agent into mutant mice that (i) lacked B cells, (ii) had B cells unable to secrete Ig, or (iii) could secrete only IgM. Remarkably, all these mice developed disease with practically indistinguishable incubation times. The demonstration that neither immune complexes nor B cells were required for neuroinvasion from the periphery mandates a reanalysis of the accepted view of the essential role of B cells and FDC in these infections. Moreover, immune complexes were not required for the accumulation of pathologic PrP on the surface of FDCs, suggesting that PrP can bind to FDCs autonomously or by means of another factor. Wild-type mice had incubation times approximately 50 days less than all mutant mice at the same peripheral doses, indicating that an intact immune system may increase agent uptake and delivery, but this condition is not essential. Specifically, the evidence to date suggests that IgG may enhance pivotal agent interactions with migratory myeloid cells.

Asunto(s)

Linfocitos B/inmunología , Síndrome de Creutzfeldt-Jakob/etiología , Células Dendríticas Foliculares/inmunología , Priones/fisiología , Animales , Ratones , Ratones Endogámicos BALB C , Ratones Transgénicos

RESUMEN

Systemic lupus erythematosus, a prototypical systemic autoimmune disease, is the result of a series of interactions within the immune system that ultimately lead to the loss of self-tolerance to nuclear autoantigens. Here, we present an integrated model that explains how self-tolerance is initially lost and how the loss of tolerance is then amplified and maintained as a chronic autoimmune state. Key to this model are the self-reinforcing interactions of T and B cells, which we suggest lead to perpetuation of autoimmunity as well as its spread to multiple autoantigen targets.

Asunto(s)

Enfermedades Autoinmunes/inmunología , Linfocitos B/inmunología , Linfocitos T/inmunología , Animales , Autoantígenos , Evolución Biológica , Comunicación Celular , Retroalimentación , Humanos , Lupus Eritematoso Sistémico/inmunología , Ratones , Modelos Inmunológicos , Autotolerancia , Transducción de Señal

Asunto(s)

Linfocitos B/inmunología , Enfermedades Desmielinizantes/inmunología , Enfermedades Desmielinizantes/fisiopatología , Virus de la Hepatitis Murina/patogenicidad , Animales , Encéfalo/inmunología , Encéfalo/virología , Enfermedades Desmielinizantes/virología , Ratones , Ratones Endogámicos C57BL , Virus de la Hepatitis Murina/inmunología , Médula Espinal/inmunología , Médula Espinal/virología

RESUMEN

Serum antibody (Ab) can play several roles during B cell immune responses. Among these is to promote the deposition of immune complexes (ICs) on follicular dendritic cells (FDCs). ICs on FDCs are generally thought to be critical for normal germinal center (GC) formation and the development and selection of memory B cells. However, it has been very difficult to test these ideas. To determine directly whether FDC-bound complexes do indeed function in these roles, we have developed a transgenic (Tg) mouse in which all B lymphocytes produce only the membrane-bound form of immunoglobulin M. Immune Tg mice have 10,000-fold less specific Ab than wild-type mice and lack detectable ICs on FDCs. Nonetheless, primary immune responses and the GC reaction in these mice are robust, suggesting that ICs on FDCs do not play critical roles in immune response initiation and GC formation. Moreover, as indicated by the presence and pattern of somatic mutations, memory cell formation and selection appear normal in these IC-deficient GCs.

Asunto(s)

Complejo Antígeno-Anticuerpo/inmunología , Linfocitos B/inmunología , Células Dendríticas Foliculares/inmunología , Centro Germinal/inmunología , Región Variable de Inmunoglobulina/inmunología , Cadenas lambda de Inmunoglobulina/inmunología , Secuencia de Aminoácidos , Animales , Anticuerpos/sangre , Femenino , Genes de Inmunoglobulinas , Haptenos/inmunología , Región Variable de Inmunoglobulina/genética , Cadenas lambda de Inmunoglobulina/genética , Masculino , Ratones , Ratones Endogámicos BALB C , Ratones Transgénicos , Datos de Secuencia Molecular , Nitrofenoles/inmunología , Fenilacetatos , Receptores de Antígenos de Linfocitos B/inmunología

RESUMEN

BACKGROUND AND PURPOSE: The clinical presentation, diagnosis, histopathologic findings, and elimination of dual respiratory tract infection with Pasteurella pneumotropica and Pneumocystis carinii were studied in 100 adult barrier-reared C.B17 and MRL- lpr mice homozygous for a targeted mutation of the JH region of the immunoglobulin heavy chain. METHODS: Necropsy, aerobic bacteriologic culture of hematogenous and pulmonary tissues, histochemical staining of pulmonary tissues, polymerase chain reaction analysis of pulmonary tissues and feces, and viral serologic testing were performed on 19 clinically affected mice and 8 clinically normal mice, then later on antibiotic-treated and caesarian re-derived mice. Therapeutic strategies included sequential administration of trimethoprim/ sulfamethoxazole and enrofloxacin or enrofloxacin administration and caesarian rederivation. RESULTS: Clinically affected mice had diffuse, nonsuppurative, interstitial pneumonia with superimposed pyogranulomatous lobar pneumonia that was detected microscopically. Affected lung tissue yielded pure culture of P. pneumotropica. Aged-matched, clinically normal mice of both genotypes had interstitial histiocytic pneumonia without lobar pneumonia, and P. pneumotropica was not isolated. Histochemical staining of lung tissues from normal and clinically affected mice revealed scattered cysts consistent with P. carinii, principally in the interstitium. Treatment with sulfamethoxazole/trimethoprim and enrofloxacin eliminated bacteriologic detection of P. pneumotropica, decreased mortality from 50% to 6%, and improved breeding performance. CONCLUSION: A successful antibiotic therapy and rederivation approach, incorporating enrofloxacin, cesarian section, and isolator rearing, was developed for B cell-deficient mice with opportunistic infections.

Asunto(s)

Fluoroquinolonas , Ratones Endogámicos ICR/inmunología , Infecciones por Pasteurella/veterinaria , Neumonía Bacteriana/veterinaria , Neumonía por Pneumocystis/veterinaria , Enfermedades de los Roedores/diagnóstico , Animales , Antibacterianos , Antiinfecciosos/uso terapéutico , Antineoplásicos/uso terapéutico , Linfocitos B/inmunología , Cesárea/veterinaria , ADN Bacteriano/química , ADN Bacteriano/aislamiento & purificación , Enrofloxacina , Heces/microbiología , Femenino , Inmunohistoquímica , Pulmón/microbiología , Pulmón/patología , Masculino , Ratones , Pasteurella/efectos de los fármacos , Pasteurella/genética , Pasteurella/inmunología , Infecciones por Pasteurella/complicaciones , Infecciones por Pasteurella/diagnóstico , Infecciones por Pasteurella/tratamiento farmacológico , Pneumocystis/efectos de los fármacos , Pneumocystis/genética , Pneumocystis/inmunología , Neumonía Bacteriana/complicaciones , Neumonía Bacteriana/tratamiento farmacológico , Neumonía por Pneumocystis/complicaciones , Neumonía por Pneumocystis/diagnóstico , Neumonía por Pneumocystis/tratamiento farmacológico , Reacción en Cadena de la Polimerasa/veterinaria , Quinolonas/uso terapéutico , Enfermedades de los Roedores/tratamiento farmacológico , Combinación Trimetoprim y Sulfametoxazol/uso terapéutico

RESUMEN

The fate of an autoreactive B cell is determined in part by the nature of the interaction of the B cell receptor with its autoantigen. In the lpr model of systemic autoimmunity, as well as in certain human diseases, autoreactive B cells expressing rheumatoid factor (RF) binding activity are prominent. A murine B cell transgenic model in which the B cell receptor is a RF that recognizes IgG2a of the j allotype (IgG2aj), but not the b allotype, was used in this study to investigate how the form of the autoantigen influences its ability to activate B cells. We found that sera from autoimmune mice, but not from nonautoimmune mice, were able to induce the proliferation of these RF+ B cells but did not stimulate B cells from RF- littermate controls. The stimulatory factor in serum was found to be IgG2aj, but the IgG2aj was stimulatory only when in the form of immune complexes. Monomeric IgG2aj failed to stimulate. Immune complexes containing lupus-associated nuclear and cytoplasmic autoantigens were particularly potent B cell activators in this system. Appropriate manipulation of such autoantibody/autoantigen complexes may eventually provide a means for therapeutic intervention in patients with certain systemic autoimmune disorders.

Asunto(s)

Complejo Antígeno-Anticuerpo/sangre , Complejo Antígeno-Anticuerpo/fisiología , Enfermedades Autoinmunes/sangre , Enfermedades Autoinmunes/inmunología , Subgrupos de Linfocitos B/inmunología , Activación de Linfocitos/inmunología , Factor Reumatoide/metabolismo , Animales , Anticuerpos Monoclonales/farmacología , Complejo Antígeno-Anticuerpo/metabolismo , Subgrupos de Linfocitos B/metabolismo , Proteína Ligando Fas , Haptenos/inmunología , Prueba de Histocompatibilidad , Calor , Sueros Inmunes/farmacología , Alotipos de Inmunoglobulinas/genética , Alotipos de Inmunoglobulinas/fisiología , Inmunoglobulina G/fisiología , Activación de Linfocitos/genética , Glicoproteínas de Membrana/deficiencia , Glicoproteínas de Membrana/genética , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Ratones Endogámicos MRL lpr , Ratones Noqueados , Ratones Transgénicos , Nucleosomas/inmunología , Factor Reumatoide/biosíntesis , Receptor fas/genética

RESUMEN

We show here that maintenance of Leishmania infections with Leishmania mexicana complex parasites (Leishmania amazonensis and Leishmania pifanoi) is impaired in the absence of circulating antibody. In these studies, we used mice genetically altered to contain no circulating antibody, with and without functional B cells. This experimental design allowed us to rule out a critical role for B cell antigen presentation in Leishmania pathogenesis. In addition, we show that mice lacking the common gamma chain of Fc receptors (FcgammaRI, FcepsilonRI, and FcgammaRIII) are similarly refractory to infection with these parasites. These observations establish a critical role for antibody in the pathogenesis associated with infection by members of the L. mexicana complex.

Asunto(s)

Leishmania mexicana/crecimiento & desarrollo , Leishmania mexicana/metabolismo , Leishmaniasis Cutánea/inmunología , Leishmaniasis Cutánea/parasitología , Receptores Fc/fisiología , Animales , Anticuerpos Antiprotozoarios/administración & dosificación , Anticuerpos Antiprotozoarios/biosíntesis , Anticuerpos Antiprotozoarios/sangre , Inmunización Pasiva , Leishmania mexicana/inmunología , Leishmaniasis Cutánea/etiología , Leishmaniasis Cutánea/genética , Ratones , Ratones Endogámicos BALB C , Ratones Noqueados , Ratones Transgénicos , Receptores Fc/deficiencia , Receptores Fc/genética , Receptores de IgG/deficiencia , Receptores de IgG/genética , Receptores de IgG/fisiología

RESUMEN

Seventy percent of peripheral immature conventional (B2) B cells fail to develop into mature B cells. The nature of this cell loss has not been characterized; the process that governs which immature B cells develop into long-lived peripheral B cells could be either stochastic or selective. Here, we demonstrate that this step is in fact selective, in that the fate of an immature B cell is highly dependent on its Ig receptor specificity. A significant skewing of the B cell receptor repertoire occurs by the time cells enter the mature B cell fraction, which indicates that there is selection of only a minority of immature B cells to become mature B cells. Because only a few heavy-light chain pairs are enhanced of the diverse available repertoire, we favor the idea that selection is positive for these few heavy-light chain pairs rather than negative against nearly all others. Because most immature B cells are lost at this transition, this putative positive selection event is likely to be a major force shaping the mature B cell receptor repertoire available for adaptive immune responses.

Asunto(s)

Linfocitos B/fisiología , Receptores de Antígenos de Linfocitos B/fisiología , Animales , Linfocitos B/citología , Linfocitos B/inmunología , Muerte Celular , Diferenciación Celular , Clonación Molecular , Citometría de Flujo , Cadenas Pesadas de Inmunoglobulina/inmunología , Cadenas Ligeras de Inmunoglobulina/inmunología , Inmunoglobulina M/inmunología , Memoria Inmunológica , Ratones , Ratones Transgénicos , Datos de Secuencia Molecular , Bazo/citología , Procesos Estocásticos

RESUMEN

Spontaneous CD8+ T cell activation in MRL-Faslpr mice is B cell dependent. It is unclear whether this B-dependent activation is mediated by direct Ag presentation via MHC class I proteins (i.e., cross-presentation) or whether activation occurs by an indirect mechanism, e.g., via effects on CD4+ cells. To determine how CD8+ T cell activation is promoted by B cells, we created mixed bone marrow chimeras where direct MHC class I Ag presentation by B cells was abrogated while other leukocyte compartments could express MHC class I. Surprisingly, despite the absence of B cell class I-restricted Ag presentation, CD8+ T cell activation was intact in the chimeric mice. Therefore, the spontaneous B cell-dependent CD8+ T cell activation that occurs in systemic autoimmunity is not due to direct presentation by B cells to CD8+ T cells.

Asunto(s)

Presentación de Antígeno/genética , Linfocitos B/inmunología , Linfocitos T CD8-positivos/inmunología , Antígenos de Histocompatibilidad Clase I/metabolismo , Activación de Linfocitos/genética , Animales , Linfocitos B/metabolismo , Médula Ósea/inmunología , Antígenos de Histocompatibilidad Clase I/genética , Antígenos de Histocompatibilidad Clase I/inmunología , Cadenas Pesadas de Inmunoglobulina/genética , Cadenas J de Inmunoglobulina/genética , Región Variable de Inmunoglobulina/genética , Cooperación Linfocítica/genética , Linfopenia/genética , Linfopenia/inmunología , Ratones , Ratones Endogámicos MRL lpr , Quimera por Radiación , Microglobulina beta-2/deficiencia , Microglobulina beta-2/genética , Microglobulina beta-2/inmunología

RESUMEN

BACKGROUND: To extend allogeneic HPC transplantation to a greater range of patients, the use of partially matched related donors is under development. Because of the inherently higher degree of histoincompatibility in such transplants, there is increased risk of GVHD as well as of graft failure. Ex vivo depletion of donor-derived T-lymphocytes from PBPCs is one of the most effective methods of preventing GVHD. Thus far, individual centers have used custom-developed procedures to deplete the graft of T cells that are responsible for alloreactivity, often employing relatively impure, nonstandardized reagents such as soybean agglutinin and complement. In addition, with improved methods of T-cell depletion, it has been difficult to accurately assess the number of T cells remaining. Because different centers have used different protocols to assay T cells, it has been difficult to reproduce and validate the results between institutions, and this has limited direct comparison of data between centers. STUDY DESIGN AND METHODS: A standardized approach for T-cell depletion was developed by using a Good Manufacturing Practice-manufactured magnetic cell separator (Isolex 300i, Nexell Therapeutics) and commercially available OKT3 antibody. T-cell depletion was performed on PBPCs from six haploidentical donors. RESULTS: CD34+ cell recovery was 47 percent (range, 31-63%) with a median purity of 94 percent (range, 75-99%) and median T-cell log depletion of 4.72 (range, 3.90-5.83). Because this high degree of depletion makes it challenging to accurately quantitate the remaining T cells, two highly sensitive flow cytometric protocols were developed, each of which accurately detects T cells with a sensitivity of 2 per 10,000 (0.02%). The purified CD34+ cells administered to the patients (dose range, 6.13-13.50 x 10(6)/kg) provided rapid neutrophil and platelet engraftment. CONCLUSION: With the Isolex 300i and a MoAb directed against T cells, a high degree of T-cell depletion is obtained. Sensitive, accurate, and reproducible assays have now been developed for T-cell enumeration in these highly purified cell populations.

Asunto(s)

Antígenos CD34/sangre , Células Madre/citología , Células Madre/inmunología , Linfocitos T/inmunología , Adulto , Donantes de Sangre , Separación Celular , Trasplante de Células/fisiología , Femenino , Citometría de Flujo , Rechazo de Injerto/inmunología , Supervivencia de Injerto/fisiología , Enfermedad Injerto contra Huésped/prevención & control , Humanos , Leucaféresis , Depleción Linfocítica , Masculino , Linfocitos T/trasplante

RESUMEN

Follicle-associated epithelium (FAE) in the intestinal Peyer's patches contains M cells that deliver pathogens to organized lymphoid tissue. Development of Peyer's patches, FAE, and M cells was found to be impaired in mice that had no B cells. Transgenic expression of membrane-bound immunoglobulin M restored B cells and FAE development. The lack of M cells abrogated infection with a milk-borne retrovirus. Thus, in addition to secretion of antibodies and presentation of antigens, B cells are important for organogenesis of the mucosal immune barriers.

Asunto(s)

Linfocitos B/inmunología , Inmunidad Mucosa , Ganglios Linfáticos Agregados/citología , Ganglios Linfáticos Agregados/inmunología , Animales , Recuento de Células , Genes de Inmunoglobulinas , Inmunoglobulina M/genética , Inmunoglobulina M/inmunología , Activación de Linfocitos , Virus del Tumor Mamario del Ratón/fisiología , Ratones , Ratones Endogámicos , Ratones Noqueados , Ratones Transgénicos , Microscopía Electrónica de Rastreo , Ganglios Linfáticos Agregados/ultraestructura , Infecciones por Retroviridae/inmunología , Infecciones por Retroviridae/virología , Linfocitos T/inmunología , Infecciones Tumorales por Virus/inmunología , Infecciones Tumorales por Virus/virología

RESUMEN

B cells are required for both the expression of lupus nephritis and spontaneous T cell activation/memory cell accumulation in MRL-Faslpr mice (MRL/lpr). Autoimmunity in the MRL/lpr strain is the result of Fas-deficiency and multiple background genes; however, the precise roles of background genes vs Fas-deficiency have not been fully defined. Fas-deficiency (i.e., the lpr defect) is required in B cells for optimal autoantibody expression, raising the possibility that the central role for B cells in MRL/lpr mice may not extend to MRL/+ mice and, thus, to lupus models that do not depend on Fas-deficiency ("polygenic lupus"). To address this issue, B cell-deficient, Fas-intact MRL/+ mice (JHd-MRL/) were created; and disease was evaluated in aged animals (>9 mo). The JHd-MRL/+ animals did not develop nephritis or vasculitis at a time when the B cell-intact littermates had severe disease. In addition, while activated/memory CD4+ and CD8+ T cells accumulated in B cell-intact mice, such accumulation was substantially inhibited in the absence of B cells. This effect appeared to be restricted to the MRL strain because it was not seen in B cell-deficient BALB/c mice (JHd-BALB) of similar ages. The results indicate that B cells are essential in promoting systemic autoimmunity in a Fas-independent model. Therefore, B cells have an important role in pathogenesis, generalizable to lupus models that depend on multiple genes even when Fas expression is intact. The results provide further rationale for B cell suppression as therapy for systemic lupus erythematosus.

Asunto(s)

Linfocitos B/inmunología , Nefritis Lúpica/genética , Nefritis Lúpica/inmunología , Herencia Multifactorial/inmunología , Animales , Linfocitos B/citología , Linfocitos B/patología , Diferenciación Celular/genética , Diferenciación Celular/inmunología , Memoria Inmunológica/genética , Inmunofenotipificación , Nefritis Lúpica/patología , Nefritis Lúpica/prevención & control , Activación de Linfocitos/genética , Linfopenia/genética , Linfopenia/inmunología , Linfopenia/patología , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos MRL lpr , Ratones Mutantes , Subgrupos de Linfocitos T/inmunología

RESUMEN

In systemic autoimmune disease, self-tolerance fails, leading to autoantibody production. A central issue in immunology is to understand the origins of activated self-reactive B cells. We have used immunoglobulin (Ig) transgenic mice to investigate the regulation of autoreactive B cells with specificity for self-IgG2a (the rheumatoid factor [RF] specificity) to understand how normal mice regulate RF autoantibodies and how this fails in autoimmune mice. We previously showed that normal mice do not tolerize the AM14 RF clone, nor do they appear to activate it. Here we show that in Fas-deficient autoimmune mice, the picture is quite different. RF B cells are activated to divide and secrete, but only when the autoantigen is present. Thus, B cells that are ignored rather than anergized in normal mice can be stimulated to produce autoantibody in Fas-deficient mice. This demonstrates a novel developmental step at which intact Fas-Fas ligand signaling is required to regulate B cells in order to prevent autoimmunity. These data also establish the relevance of ignorant self-specific B cells to autoantibody production in disease and prove that in the case of the RF specificity, the nominal autoantigen IgG2a is the driving autoantigen in vivo.

Asunto(s)

Autoantígenos , Linfocitos B/inmunología , Factor Reumatoide/inmunología , Receptor fas/metabolismo , Animales , Autoanticuerpos/biosíntesis , Enfermedades Autoinmunes/genética , Enfermedades Autoinmunes/inmunología , Enfermedades Autoinmunes/patología , Autoinmunidad , Inmunoglobulina G/genética , Cadenas Pesadas de Inmunoglobulina/genética , Activación de Linfocitos , Recuento de Linfocitos , Ratones , Ratones Endogámicos BALB C , Ratones Transgénicos , Autotolerancia , Bazo/citología , Bazo/inmunología , Linfocitos T/inmunología

RESUMEN

A standard view of B cells in systemic autoimmunity is that they promote lupus by producing autoantibodies (autoAb). However, this view is incomplete because recent studies have revealed that autoimmune disease can be dissociated from autoAb deposition. Furthermore, the spontaneous T-cell activation and organ infiltration in systemic lupus erythematosus patients and animal models are difficult to explain entirely via a direct autoAb-mediated mechanism. In this review, we describe work addressing the B-cell functions of autoantigen presentation and autoAb production in lupus pathogenesis. In the JHD-MRL-Faslpr strain (JHD/lpr), a B-cell-deficient version of the lupus-prone MRL-Faslpr (MRL/lpr) mouse, spontaneous nephritis and dermatitis is abrogated, demonstrating that B cells have a primary role in disease. B cells play a similar role in Fas-intact, lupus-prone MRL mice. To address the role of autoantigen presentation, we analyzed transgenic mice which have B cells that cannot secrete immunoglobulin (mIgM transgenic mice). The restoration of B cells without antibody caused substantial interstitial nephritis and vasculitis although less marked than the intact MRL/lpr controls. To address the role of autoAb, we infused serum from aged MRL/lpr mice into JHD/lpr mice. At most, mild to no nephritis was observed in the infused mice. These results indicate that B cells are promoting autoimmunity in mechanisms other than autoAb secretion, and we describe a model depicting these B-cell roles in the context of other inflammatory events in lupus.

Asunto(s)

Linfocitos B/inmunología , Lupus Eritematoso Sistémico/inmunología , Animales , Células Presentadoras de Antígenos/inmunología , Autoinmunidad , Modelos Animales de Enfermedad , Humanos , Lupus Eritematoso Sistémico/etiología , Lupus Eritematoso Sistémico/genética , Nefritis Lúpica/genética , Nefritis Lúpica/inmunología , Nefritis Lúpica/patología , Activación de Linfocitos , Ratones , Ratones Endogámicos MRL lpr , Ratones Noqueados , Linfocitos T/inmunología

RESUMEN

Graft versus host disease, an alloimmune attack on host tissues mounted by donor T cells, is the most important toxicity of allogeneic bone marrow transplantation. The mechanism by which allogeneic T cells are initially stimulated is unknown. In a murine allogeneic bone marrow transplantation model it was found that, despite the presence of numerous donor antigen-presenting cells, only host-derived antigen-presenting cells initiated graft versus host disease. Thus, strategies for preventing graft versus host disease could be developed that are based on inactivating host antigen-presenting cells. Such strategies could expand the safety and application of allogeneic bone marrow transplantation in treatment of common genetic and neoplastic diseases.

Asunto(s)

Células Presentadoras de Antígenos/inmunología , Trasplante de Médula Ósea/inmunología , Linfocitos T CD8-positivos/inmunología , Enfermedad Injerto contra Huésped/prevención & control , Animales , Trasplante de Médula Ósea/efectos adversos , Células Dendríticas/inmunología , Enfermedad Injerto contra Huésped/inmunología , Antígenos H-2/inmunología , Ganglios Linfáticos/inmunología , Ratones , Ratones Endogámicos C3H , Ratones Endogámicos C57BL , Ratones Endogámicos , Ratones Noqueados , Antígenos de Histocompatibilidad Menor/inmunología , Bazo/inmunología , Quimera por Trasplante

RESUMEN

The precise role of B cells in systemic autoimmunity is incompletely understood. Although B cells are necessary for expression of disease (Chan, O., and M.J. Shlomchik. 1998. J. Immunol. 160:51-59, and Shlomchik, M.J., M.P. Madaio, D. Ni, M. Trounstine, and D. Huszar. 1994. J. Exp. Med. 180:1295-1306), it is unclear whether autoantibody production, antigen presentation, and/or other B cell functions are required for the complete pathologic phenotype. To address this issue, two experimental approaches were used. In the first, the individual contributions of circulating antibodies and B cells were analyzed using MRL/MpJ-Faslpr (MRL/lpr) mice that expressed a mutant transgene encoding surface immunoglobulin (Ig), but which did not permit the secretion of circulating Ig. These mice developed nephritis, characterized by cellular infiltration within the kidney, indicating that B cells themselves, without soluble autoantibody production, exert a pathogenic role. The results indicate that, independent of serum autoantibody, functional B cells expressing surface Ig are essential for disease expression, either by serving as antigen-presenting cells for antigen-specific, autoreactive T cells, or by contributing directly to local inflammation.

Asunto(s)

Anticuerpos/sangre , Linfocitos B/inmunología , Lupus Vulgar/inmunología , Animales , Células Presentadoras de Antígenos/inmunología , Autoinmunidad/inmunología , Modelos Animales de Enfermedad , Inmunoglobulina G/genética , Inmunoglobulina G/inmunología , Inmunoglobulina M/genética , Inmunoglobulina M/inmunología , Lupus Vulgar/genética , Ganglios Linfáticos/inmunología , Ratones , Ratones Transgénicos , Mutación , Nefritis/inmunología , Tamaño de los Órganos , Fenotipo , Bazo/inmunología , Linfocitos T/inmunología