RESUMEN

While immune responses have been rigorously examined after intravenous Listeria monocytogenes (Lm) infection, less is understood about its dissemination from the intestines or the induction of adaptive immunity after more physiologic models of foodborne infection. Consequently, this study focused on early events in the intestinal mucosa and draining mesenteric lymph nodes (MLN) using foodborne infection of mice with Lm modified to invade murine intestinal epithelium (InlAMLm). InlAMLm trafficked intracellularly from the intestines to the MLN and were associated with Batf3-independent dendritic cells (DC) in the lymphatics. Consistent with this, InlAMLm initially disseminated from the gut to the MLN normally in Batf3-/- mice. Activated migratory DC accumulated in the MLN by 3 days post-infection and surrounded foci of InlAMLm. At this time Batf3-/- mice displayed reduced InlAMLm burdens, implicating cDC1 in maximal bacterial accumulation in the MLN. Batf3-/- mice also exhibited profound defects in the induction and gut-homing of InlAMLm-specific effector CD8 T cells. Restoration of pathogen burden did not rescue antigen-specific CD8 T cell responses in Batf3-/- mice, indicating a critical role for Batf3 in generating anti-InlAMLm immunity following foodborne infection. Collectively, these data suggest that DC play diverse, dynamic roles in the early events following foodborne InlAMLm infection and in driving the establishment of intestinal Lm-specific effector T cells.

Asunto(s)

Factores de Transcripción con Cremalleras de Leucina de Carácter Básico/metabolismo , Linfocitos T CD8-positivos/metabolismo , Células Dendríticas/metabolismo , Enfermedades Transmitidas por los Alimentos/metabolismo , Inmunidad Mucosa , Mucosa Intestinal/metabolismo , Intestino Delgado/metabolismo , Listeria monocytogenes/patogenicidad , Listeriosis/metabolismo , Ganglios Linfáticos/metabolismo , Proteínas Represoras/metabolismo , Animales , Factores de Transcripción con Cremalleras de Leucina de Carácter Básico/genética , Linfocitos T CD8-positivos/inmunología , Linfocitos T CD8-positivos/microbiología , Células Cultivadas , Quimiotaxis de Leucocito , Células Dendríticas/inmunología , Células Dendríticas/microbiología , Modelos Animales de Enfermedad , Femenino , Enfermedades Transmitidas por los Alimentos/genética , Enfermedades Transmitidas por los Alimentos/inmunología , Enfermedades Transmitidas por los Alimentos/microbiología , Interacciones Huésped-Patógeno , Mucosa Intestinal/inmunología , Mucosa Intestinal/microbiología , Intestino Delgado/inmunología , Intestino Delgado/microbiología , Listeria monocytogenes/genética , Listeria monocytogenes/inmunología , Listeriosis/genética , Listeriosis/inmunología , Listeriosis/microbiología , Ganglios Linfáticos/inmunología , Ganglios Linfáticos/microbiología , Masculino , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Ratones Noqueados , Proteínas Represoras/genética

RESUMEN

Memory γδ T cells are important for the clearance of Listeria monocytogenes infection in the intestinal mucosa. However, the mechanisms by which memory γδ T cells provide protection against secondary oral infection are poorly understood. Here we used a recombinant strain of L. monocytogenes that efficiently invades the intestinal epithelium to show that Vγ4(+) memory γδ T cells represent a resident memory (Trm) population in the mesenteric lymph nodes (MLNs). The γδ Trm exhibited a remarkably static pattern of migration that radically changed following secondary oral L. monocytogenes infection. The γδ Trms produced IL-17A early after rechallenge and formed organized clusters with myeloid cells surrounding L. monocytogenes replication foci only after a secondary oral infection. Antibody blocking studies showed that in addition to IL-17A, the chemokine receptor C-X-C chemokine receptor 3 (CXCR3) is also important to enable the local redistribution of γδ Trm cells and myeloid cells specifically near the sites of L. monocytogenes replication within the MLN to restrict bacterial growth and spread. Our findings support a role for γδ Trms in orchestrating protective immune responses against intestinal pathogens.

Asunto(s)

Inmunidad Innata/inmunología , Interleucina-17/inmunología , Listeria monocytogenes/inmunología , Listeriosis/inmunología , Receptores de Antígenos de Linfocitos T gamma-delta/inmunología , Subgrupos de Linfocitos T/inmunología , Animales , Movimiento Celular/inmunología , Femenino , Memoria Inmunológica/inmunología , Interleucina-17/metabolismo , Mucosa Intestinal/inmunología , Mucosa Intestinal/metabolismo , Mucosa Intestinal/microbiología , Listeria monocytogenes/fisiología , Listeriosis/metabolismo , Listeriosis/microbiología , Ganglios Linfáticos/inmunología , Mesenterio/inmunología , Ratones Endogámicos BALB C , Ratones Transgénicos , Células Mieloides/inmunología , Receptores de Antígenos de Linfocitos T gamma-delta/genética , Receptores de Antígenos de Linfocitos T gamma-delta/metabolismo , Receptores CXCR3/inmunología , Receptores CXCR3/metabolismo , Subgrupos de Linfocitos T/metabolismo

RESUMEN

CCR7 is an important chemokine receptor that regulates T cell trafficking and compartmentalization within secondary lymphoid organs. However, the T cell-intrinsic role of CCR7 during infection in the spleen is not well understood. This study was designed to understand how CCR7-dependent localization and migration of CD8(+) T cells in different compartments of the spleen affected the primary and recall responses after infection. To this end, we used adoptive transfer of naive Ag-specific CD8 T cells (OT-I) that either lacked CCR7 or constitutively expressed CCR7 (CD2-CCR7) in mice that were subsequently infected i.v. with Listeria monocytogenes. We show that naive CCR7(-/-)CD8(+) T cells failed to enter the T cell zone, whereas CD2-CCR7 OT-I cells were exclusively confined to the T cell zones of the spleen. Surprisingly, however, CCR7(-/-) OT-I cells entered the T cell zones after infection, but the entry and egress migratory pattern of these cells was dysregulated and very distinct compared with wild-type OT-I cells. Moreover, CCR7-deficient OT-I cells failed to expand robustly when compared with wild-type OT-I cells and were preferentially skewed toward a short-lived effector cell differentiation pattern. Interestingly, CCR7(-/-), CD2-CCR7, and wild-type OT-I memory cells responded equally well to rechallenge infection. These results highlight a novel role of CCR7 in regulating effector CD8 T cell migration in the spleen and demonstrate differential requirement of CCR7 for primary and secondary CD8 T cell responses to infection.

Asunto(s)

Linfocitos T CD8-positivos/inmunología , Movimiento Celular/inmunología , Listeria monocytogenes/inmunología , Receptores CCR7/genética , Bazo/inmunología , Traslado Adoptivo , Animales , Linfocitos T CD8-positivos/citología , Diferenciación Celular/inmunología , Memoria Inmunológica/inmunología , Listeriosis/inmunología , Activación de Linfocitos/genética , Activación de Linfocitos/inmunología , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Receptores CCR7/biosíntesis , Bazo/citología

RESUMEN

Naïve antigen-specific CD8 T cells expand in response to infection and can be phenotypically separated into distinct effector populations, which include memory precursor effector cells (MPECs) and short-lived effector cells (SLECs). In the days before the peak of the T cell response, a third population called early effector cells (EECs) predominate the antigen-specific response. However, the contribution of the EEC population to the CD8 T cell differentiation program during an antimicrobial immune response is not well understood. To test if EEC populations were pre-committed to either an MPEC or SLEC fate, we purified EECs from mice infected with Listeria monocytogenes (LM) or vesicular stomatitis virus (VSV), where the relative frequency of each population is known to be different at the peak of the response. Sorted EECs transferred into uninfected hosts revealed that EECs were pre-programmed to differentiate based on early signals received from the distinct infectious environments. Surprisingly, when these same EECs were transferred early into mismatched infected hosts, the transferred EECs could be diverted from their original fate. These results delineate a model of differentiation where EECs are programmed to form MPECs or SLECs, but remain susceptible to additional inflammatory stimuli that can alter their fate.

Asunto(s)

Infecciones Bacterianas/inmunología , Linfocitos T CD8-positivos/inmunología , Memoria Inmunológica , Virosis/inmunología , Animales , Antígenos/inmunología , Linfocitos T CD8-positivos/citología , Diferenciación Celular , Proliferación Celular , Femenino , Genoma , Inflamación/inmunología , Inflamación/patología , Activación de Linfocitos/inmunología , Ratones Endogámicos C57BL , Análisis de Secuencia por Matrices de Oligonucleótidos , Transducción de Señal , Vesiculovirus/fisiología

RESUMEN

The development and homeostasis of γδ T cells is highly dependent on distinct cytokine networks. Here we examine the role of IL-15 and its unique receptor, IL-15Rα, in the development of IL-17-producing γδ (γδ-17) T cells. Phenotypic analysis has shown that CD44(high) γδ-17 cells express IL-15Rα and the common gamma chain (CD132), yet lack the IL-2/15Rß chain (CD122). Surprisingly, we found an enlarged population of γδ-17 cells in the peripheral and mesenteric lymph nodes of adult IL-15Rα KO mice, but not of IL-15 KO mice. The generation of mixed chimeras from neonatal thymocytes indicated that cell-intrinsic IL-15Rα expression was required to limit IL-17 production by γδ T cells. γδ-17 cells also were increased in the peripheral lymph nodes of transgenic knock-in mice, where the IL-15Rα intracellular signaling domain was replaced with the intracellular portion of the IL-2Rα chain (that lacks signaling capacity). Finally, an analysis of neonatal thymi revealed that the CD44(lo/int) precursors of γδ-17 cells, which also expressed IL-15Rα, were increased in newborn mice deficient in IL-15Rα signaling, but not in IL-15 itself. Thus, these findings demonstrate that signaling through IL-15Rα regulates the development of γδ-17 cells early in ontogeny, with long-term effects on their peripheral homeostasis in the adult.

Asunto(s)

Subunidad alfa del Receptor de Interleucina-15/metabolismo , Interleucina-17/biosíntesis , Receptores de Antígenos de Linfocitos T gamma-delta/metabolismo , Transducción de Señal , Linfocitos T/citología , Linfocitos T/metabolismo , Animales , Animales Recién Nacidos , Antígenos CD/metabolismo , Movimiento Celular , Fluorescencia , Subunidad alfa del Receptor de Interleucina-15/deficiencia , Subunidad alfa del Receptor de Interleucina-2/metabolismo , Ratones Endogámicos C57BL , Ratones Noqueados , Timo/citología

RESUMEN

The process of lymphopoiesis begins in the bone marrow (BM) and requires multiple cellular intermediates. For T cell production, lymphoid progenitors exit the BM and home to the thymus where maturation and selection ensue. These processes are dependent on a number of factors, including chemokines and adhesion molecules. Although the ß2 integrin CD11a plays an important role in the migration of lymphocytes to lymph nodes, the role of CD11a in T cell development is largely undefined. Our studies now show that, in CD11a(-/-) mice, thymic cellularity was decreased and early T cell development was partially impaired. Remarkably, CD11a was critical for generation of common lymphoid progenitors (CLPs) and lymphoid-primed multipotent progenitors. However, in intact CD11a(-/-) mice, peripheral B and T cell subsets were only modestly altered, suggesting that compensatory mechanisms were operating. In contrast, competitive BM-reconstitution assays revealed an essential role for CD11a in the generation of thymocytes and mature T and B cells. This defect was linked to the requirement for CD11a in the development of CLPs. Furthermore, our results identified CLPs, and not lymphoid-primed multipotent progenitors, as the requisite CD11a-dependent precursor for lymphocyte development. Thus, these findings established a key role for CD11a in lymphopoiesis.

Asunto(s)

Linfocitos B/inmunología , Antígeno CD11a/genética , Células Progenitoras Linfoides/inmunología , Linfopoyesis/genética , Linfocitos T/inmunología , Animales , Linfocitos B/citología , Células de la Médula Ósea/inmunología , Linaje de la Célula , Expresión Génica , Células Progenitoras Linfoides/metabolismo , Linfopoyesis/inmunología , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Linfocitos T/citología

RESUMEN

The intestinal mucosa promotes T cell responses that might be beneficial for effective mucosal vaccines. However, intestinal resident memory T (Trm) cell formation and function are poorly understood. We found that oral infection with Listeria monocytogenes induced a robust intestinal CD8 T cell response and blocking effector T cell migration showed that intestinal Trm cells were critical for secondary protection. Intestinal effector CD8 T cells were predominately composed of memory precursor effector cells (MPECs) that rapidly upregulated CD103, which was needed for T cell accumulation in the intestinal epithelium. CD103 expression, rapid MPEC formation, and maintenance in intestinal tissues were dependent on T cell intrinsic transforming growth factor ß signals. Moreover, intestinal Trm cells generated after intranasal or intravenous infection were less robust and phenotypically distinct from Trm cells generated after oral infection, demonstrating the critical contribution of infection route for directing the generation of protective intestinal Trm cells.

Asunto(s)

Linfocitos T CD8-positivos/inmunología , Mucosa Intestinal/inmunología , Listeria monocytogenes/inmunología , Listeriosis/inmunología , Listeriosis/transmisión , Enfermedades de la Boca/microbiología , Administración Oral , Traslado Adoptivo , Animales , Antígenos CD/biosíntesis , Movimiento Celular/inmunología , Memoria Inmunológica/inmunología , Cadenas alfa de Integrinas/biosíntesis , Mucosa Intestinal/citología , Listeria monocytogenes/genética , Activación de Linfocitos/inmunología , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Ratones Noqueados , Factor de Crecimiento Transformador beta/inmunología

Asunto(s)

Infecciones Bacterianas/historia , Linfocitos T CD8-positivos/inmunología , Memoria Inmunológica , Linfocitos T Colaboradores-Inductores/inmunología , Virosis/historia , Inmunidad Adaptativa , Animales , Infecciones Bacterianas/inmunología , Historia del Siglo XXI , Ratones , Ratones Endogámicos C57BL , Especificidad de Órganos , Virus de la Estomatitis Vesicular Indiana/inmunología , Virosis/inmunología

RESUMEN

Many studies have examined pathways controlling effector T cell differentiation, but less is known about the fate of individual CD8+ T cells during infection. Here, we examine the antiviral and antibacterial responses of single CD8+ T cells from the polyclonal repertoire. The progeny of naive clonal CD8+ T cells displayed unique profiles of differentiation based on extrinsic pathogen-induced environmental cues, with some clones demonstrating extreme bias toward a single developmental pathway. Moreover, even within the same animal, a single naive CD8+ T cell exhibited distinct fates that were controlled by tissue-specific events. However, memory CD8+ T cells relied on intrinsic factors to control differentiation upon challenge. Our results demonstrate that stochastic and instructive events differentially contribute to shaping the primary and secondary CD8+ T cell response and provide insight into the underlying forces that drive effector differentiation and protective memory formation.

Asunto(s)

Linfocitos T CD8-positivos/inmunología , Listeriosis/inmunología , Estomatitis Vesicular/inmunología , Animales , Diferenciación Celular , Femenino , Memoria Inmunológica , Listeria monocytogenes/inmunología , Activación de Linfocitos , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Virus de la Estomatitis Vesicular Indiana/inmunología

RESUMEN

Dendritic cells (DCs) are the most commonly studied source of the cytokine IL-15. Using an IL-15 reporter transgenic mouse, we have recently shown previously unappreciated differences in the levels of IL-15 expressed by subsets of conventional DCs (CD8⁺ and CD8⁻). In this study, we show that IL-15 promoter activity was differentially regulated in subsets of hematopoietically derived cells with IL-15 expression largely limited to myeloid lineages. In contrast, mature cells of the lymphoid lineages expressed little to no IL-15 activity. Surprisingly, we discovered that hematopoietic stem cells (lineage⁻Sca-1⁺c-Kit⁺) expressed high levels of IL-15, suggesting that IL-15 expression was extinguished during lymphoid development. In the case of T cells, this downregulation was Notch-dependent and occurred in a stepwise pattern coincident with increasing maturation and commitment to a T cell fate. Finally, we further demonstrate that IL-15 expression was also controlled throughout DC development, with key regulatory activity of IL-15 production occurring at the pre-DC branch point, leading to the generation of both IL-15⁺CD8⁺ and IL-15(⁻/low)CD8⁻ DC subsets. Thus, IL-15 expression is coordinated with cellular fate in myeloid versus lymphoid immune cells.

Asunto(s)

Regulación de la Expresión Génica/inmunología , Hematopoyesis/inmunología , Células Madre Hematopoyéticas/inmunología , Interleucina-15/biosíntesis , Traslado Adoptivo , Animales , Diferenciación Celular/inmunología , Linaje de la Célula , Separación Celular , Citometría de Flujo , Células Madre Hematopoyéticas/citología , Interleucina-15/inmunología , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Células Mieloides/inmunología , Transcripción Genética

RESUMEN

The study of T cell memory and the target of vaccine design have focused on memory subsumed by T cells bearing the αß T cell receptor. Alternatively, γδ T cells are thought to provide rapid immunity, particularly at mucosal borders. Here, we have shown that a distinct subset of mucosal γδ T cells mounts an immune response to oral Listeria monocytogenes (Lm) infection and leads to the development of multifunctional memory T cells capable of simultaneously producing interferon-γ and interleukin-17A in the murine intestinal mucosa. Challenge infection with oral Lm, but not oral Salmonella or intravenous Lm, induced rapid expansion of memory γδ T cells, suggesting contextual specificity to the priming pathogen. Importantly, memory γδ T cells were able to provide enhanced protection against infection. These findings illustrate that γδ T cells play a role with hallmarks of adaptive immunity in the intestinal mucosa.

Asunto(s)

Memoria Inmunológica/inmunología , Intestinos/inmunología , Receptores de Antígenos de Linfocitos T gamma-delta/inmunología , Linfocitos T/inmunología , Inmunidad Adaptativa/inmunología , Secuencia de Aminoácidos , Animales , Células Cultivadas , Femenino , Citometría de Flujo , Interacciones Huésped-Patógeno/inmunología , Receptores de Hialuranos/inmunología , Receptores de Hialuranos/metabolismo , Interferón gamma/inmunología , Interferón gamma/metabolismo , Interleucina-17/inmunología , Interleucina-17/metabolismo , Mucosa Intestinal/inmunología , Mucosa Intestinal/metabolismo , Listeria monocytogenes/inmunología , Listeria monocytogenes/fisiología , Listeriosis/inmunología , Listeriosis/metabolismo , Ratones , Ratones Congénicos , Ratones Endogámicos BALB C , Receptores de Antígenos de Linfocitos T gamma-delta/genética , Receptores de Antígenos de Linfocitos T gamma-delta/metabolismo , Subgrupos de Linfocitos T/inmunología , Subgrupos de Linfocitos T/metabolismo , Linfocitos T/metabolismo , Miembro 7 de la Superfamilia de Receptores de Factores de Necrosis Tumoral/inmunología , Miembro 7 de la Superfamilia de Receptores de Factores de Necrosis Tumoral/metabolismo

RESUMEN

In healthy individuals, influenza virus (IAV) infection generally remains localized to the epithelial cells of the respiratory tract. Previously, IAV-specific effector CD8 T cells found systemically during the course of IAV infection were thought to have been primed in lung-draining lymph nodes with subsequent migration to other tissues. However, little is known about whether other lymphoid sites participate in the generation of virus-specific CD8 T cells during localized IAV infection. Here, we present evidence of early CD8 T cell priming in the spleen following respiratory IAV infection independent of lung-draining lymph node priming of T cells. Although we found early indications of CD8 T cell activation in the lymph nodes draining the respiratory tract, we also saw evidence of virus-specific CD8 T cell activation in the spleen. Furthermore, CD8 T cells primed in the spleen differentiated into memory cells of equivalent longevity and with similar recall capacity as CD8 T cells primed in the draining lymph nodes. These data showed that the spleen contributes to the virus-specific effector and memory CD8 T cell populations that are generated in response to respiratory infection.

Asunto(s)

Linfocitos T CD8-positivos/inmunología , Virus de la Influenza A/inmunología , Infecciones por Orthomyxoviridae/inmunología , Infecciones del Sistema Respiratorio/inmunología , Bazo/inmunología , Bazo/virología , Animales , Modelos Animales de Enfermedad , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Infecciones por Orthomyxoviridae/virología , Infecciones del Sistema Respiratorio/virología

RESUMEN

Programmed death ligand-1 (PD-L1) is an important negative regulator of T cell immune responses via interactions with PD-1 and CD80. However, PD-L1 can also act as a positive costimulator, but the relevant counterreceptor is not known. We analyzed the role of PD-L1 in CD8-T cell responses to infection with Listeria monocytogenes (LM) or vesicular stomatitis virus (VSV). PD-L1 blockade impaired antigen-specific CD8 effector T cell expansion in response to LM, but not to VSV infection, particularly limiting short-lived effector cell differentiation. Simultaneous CD4-T cell depletion and anti-PD-L1 blockade revealed that PD-L1 provided costimulation even in the absence of CD4-T cells. Most importantly, specific blockade of PD-L1 binding to CD80 or to PD-1 did not recapitulate PDL-1 blockade. The results suggested that PD-L1 plays an important costimulatory role for antigen-specific CD8 T cells during LM infection perhaps through a distinct receptor or interaction epitope.

Asunto(s)

Antígeno B7-H1/inmunología , Linfocitos T CD8-positivos/inmunología , Listeria monocytogenes/inmunología , Listeriosis/inmunología , Transducción de Señal , Animales , Anticuerpos Monoclonales/inmunología , Antígenos de Diferenciación/inmunología , Antígeno B7-1/inmunología , Antígeno B7-H1/metabolismo , Linfocitos T CD8-positivos/citología , Diferenciación Celular , Proliferación Celular , Epítopos de Linfocito T/inmunología , Listeriosis/microbiología , Ratones , Ratones Endogámicos C57BL , Receptor de Muerte Celular Programada 1 , Infecciones por Rhabdoviridae/inmunología , Infecciones por Rhabdoviridae/virología , Subgrupos de Linfocitos T/citología , Subgrupos de Linfocitos T/inmunología , Regulación hacia Arriba , Vesiculovirus/inmunología

RESUMEN

ß2 (CD18) integrins with α-chains CD11a, -b, -c, and -d are important adhesion molecules necessary for leukocyte migration and cellular interactions. CD18 deficiency leads to recurrent bacterial infections and poor wound healing due to reduced migration of leukocytes to inflammatory sites. CD8 T cells also upregulate CD11a, CD11b, and CD11c upon activation. However, the role these molecules play for CD8 T cells in vivo is not known. To determine the function of individual ß2 integrins, we examined CD8 T cell responses to Listeria monocytogenes infection in CD11a-, CD11b-, and CD11c-deficient mice. The absence of CD11b or CD11c had no effect on the generation of antigen-specific CD8 T cells. In contrast, the magnitude of the primary CD8 T cell response in CD11a-deficient mice was significantly reduced. Moreover, the response in CD11a(-/-) mice exhibited reduced differentiation of short-lived effector cells (KLRG1(hi) CD127(lo)), although cytokine and granzyme B production levels were unaffected. Notably, CD11a deficiency resulted in greatly enhanced generation of CD62L(+) central memory cells. Surprisingly, CD8 T cells lacking CD11a mounted a robust secondary response to infection. Taken together, these findings demonstrated that CD11a expression contributes to expansion and differentiation of primary CD8 T cells but may be dispensable for secondary responses to infection.

Asunto(s)

Antígeno CD11a/metabolismo , Linfocitos T CD8-positivos/inmunología , Interacciones Huésped-Patógeno , Listeria monocytogenes/inmunología , Animales , Modelos Animales de Enfermedad , Memoria Inmunológica , Listeriosis/inmunología , Listeriosis/patología , Ratones , Ratones Noqueados

RESUMEN

Peripheral tolerance to developmentally regulated antigens is necessary to sustain tissue homeostasis. We have now devised an inducible and reversible system that allows interrogation of T-cell tolerance induction in endogenous naïve and memory CD8 T cells. Our data show that peripheral CD8 T-cell tolerance can be preserved through two distinct mechanisms, antigen addiction leading to anergy for naïve T cells and ignorance for memory T cells. Induction of antigen in dendritic cells resulted in substantial expansion and maintenance of endogenous antigen-specific CD8 T cells. The self-reactive cells initially exhibited effector activity but eventually became unresponsive. Upon antigen removal, the antigen-specific population waned, resulting in development of a self-specific memory subset that recalled to subsequent challenge. In striking contrast to naïve CD8 T cells, preexisting antigen-specific memory CD8 T cells failed to expand after antigen induction and essentially ignored the antigen despite widespread expression by dendritic cells. The inclusion of inflammatory signals partially overcame memory CD8 T-cell ignorance of self-antigen. Thus, peripheral CD8 T-cell tolerance for naïve CD8 T cells depended on the continuous presence of antigen, whereas memory CD8 T cells were prohibited from autoreactivity in the absence of inflammation.

Asunto(s)

Linfocitos T CD8-positivos/inmunología , Tolerancia Inmunológica/inmunología , Memoria Inmunológica/inmunología , Animales , Autoantígenos/inmunología , Antígenos CD8/inmunología , Linfocitos T CD8-positivos/citología , Activación de Linfocitos/inmunología , Tejido Linfoide/citología , Tejido Linfoide/inmunología , Ratones , Ratones Transgénicos

RESUMEN

The isolation of lymphocytes and other hematopoietic-derived cells from small intestinal tissues has become increasingly relevant to immunology over the last decade. It is also becoming increasingly clear that the impact of local immunity at the mucosal barrier of the intestine has a profound impact on immune responses at distant sites, bringing a new cadre of immunologists to the mucosal frontier. Furthermore, the ability to experimentally manipulate smaller and smaller populations of immune cells has become technologically feasible and in some cases routine. The expanding importance of mucosal immunology coupled with increased technical capabilities requires a standard for experimentally obtaining uniform and consistent cells from the intestinal mucosa. Therefore, it is important to isolate immune cells that are highly viable and minimally manipulated to maximize cellular yields while maintaining acceptable time constraints.

Asunto(s)

Separación Celular/métodos , Mucosa Intestinal/metabolismo , Intestino Delgado/inmunología , Linfocitos/inmunología , Ganglios Linfáticos Agregados/inmunología , Animales , Técnicas de Cultivo de Célula , Células Cultivadas , Citometría de Flujo , Humanos , Inmunidad Mucosa , Mucosa Intestinal/citología , Linfocitos/citología , Ratones , Ganglios Linfáticos Agregados/citología

RESUMEN

Nonlymphoid T cell populations control local infections and contribute to inflammatory diseases, thus driving efforts to understand the regulation of their migration, differentiation, and maintenance. Numerous observations indicate that T cell trafficking and differentiation within the lung are starkly different from what has been described in most nonlymphoid tissues, including intestine and skin. After systemic infection, we found that >95% of memory CD8 T cells isolated from mouse lung via standard methods were actually confined to the pulmonary vasculature, despite perfusion. A respiratory route of challenge increased virus-specific T cell localization within lung tissue, although only transiently. Removing blood-borne cells from analysis by the simple technique of intravascular staining revealed distinct phenotypic signatures and chemokine-dependent trafficking restricted to Ag-experienced T cells. These results precipitate a revised model for pulmonary T cell trafficking and differentiation and a re-evaluation of studies examining the contributions of pulmonary T cells to protection and disease.

Asunto(s)

Linfocitos T CD8-positivos/inmunología , Linfocitos T CD8-positivos/patología , Capilares/inmunología , Capilares/patología , Pulmón/irrigación sanguínea , Pulmón/inmunología , Animales , Anticuerpos/administración & dosificación , Antígenos CD8/inmunología , Linfocitos T CD8-positivos/trasplante , Capilares/virología , Movimiento Celular/genética , Movimiento Celular/inmunología , Pulmón/metabolismo , Coriomeningitis Linfocítica/genética , Coriomeningitis Linfocítica/inmunología , Coriomeningitis Linfocítica/patología , Ratones , Ratones Endogámicos C57BL , Ratones Mutantes , Toxina del Pertussis/administración & dosificación , Neumonía Viral/genética , Neumonía Viral/inmunología , Neumonía Viral/patología , Bazo/inmunología , Bazo/patología , Bazo/trasplante , Coloración y Etiquetado/métodos

RESUMEN

The role of CD8(+) T cells in the pathogenesis of asthma remains controversial, as both pro- and anti-inflammatory functions have been suggested. This study was designed to examine the endogenous CD8(+) T cell response in a biphasic ovalbumin (OVA)-induced model of allergic airway disease (AAD) and its subsequent resolution with the development of local inhalational tolerance (LIT). We observed increases in OVA-specific CD8(+) T cell numbers in the local lung compartments (bronchoalveolar lavage, lung tissue, hilar lymph node) at AAD and LIT; systemic compartments (spleen, inguinal lymph node) displayed no such increases in CD8(+) T cell numbers. OVA-specific CD8(+) T cells appeared to exhibit plasticity both phenotypically and functionally. They possessed pro-inflammatory characteristics at AAD, with high phenotypic expression of CD11a and increased functional expression of granzyme B and interferon-γ. In contrast, at LIT they showed increased phenotypic expression of the inhibitory marker NKG2A and functionally did not produce granzyme B or interferon-γ. In addition, in a discontinuous model the OVA-specific CD8(+) T cells could be recalled on re-exposure to OVA, demonstrating memory. Finally, confocal microscopy results showed that OVA-specific CD8(+) T cells at AAD are associated with B cell aggregates in lung tissue. These B cell aggregates resembled tertiary ectopic lymphoid tissue and may thus provide a local environment for the salient cellular interactions that contribute to the development of LIT.

Asunto(s)

Linfocitos T CD8-positivos/inmunología , Hipersensibilidad Respiratoria/inmunología , Administración por Inhalación , Animales , Linfocitos B/inmunología , Bronquios/inmunología , Líquido del Lavado Bronquioalveolar/inmunología , Agregación Celular/inmunología , Femenino , Granzimas/metabolismo , Tolerancia Inmunológica , Memoria Inmunológica , Inmunofenotipificación , Interferón gamma/metabolismo , Pulmón/inmunología , Ganglios Linfáticos/inmunología , Activación de Linfocitos/inmunología , Ratones , Ratones Endogámicos C57BL , Microscopía Confocal , Subfamília C de Receptores Similares a Lectina de Células NK/análisis , Ovalbúmina/administración & dosificación , Ovalbúmina/inmunología , Linfocitos T Reguladores/inmunología

RESUMEN

B cell antibody production is thought to be crucial for protection against virus infection. In this issue of Immunity, Moseman et al. (2012) illustrate an antibody-independent role for B cells in macrophage activation that prevents virus dissemination after subcutaneous infection.

RESUMEN

IL-15 plays a multifaceted role in immune homeostasis, but the unreliability of IL-15 detection has stymied exploration of IL-15 regulation in vivo. To visualize IL-15 expression, we created a transgenic mouse expressing emerald-GFP (EmGFP) under IL-15 promoter control. EmGFP/IL-15 was prevalent in innate cells including dendritic cells (DCs), macrophages, and monocytes. However, DC subsets expressed varying levels of EmGFP/IL-15 with CD8(+) DCs constitutively expressing EmGFP/IL-15 and CD8(-) DCs expressing low EmGFP/IL-15 levels. Virus infection resulted in IL-15 upregulation in both subsets. By crossing the transgenic mice to mice deficient in specific elements of innate signaling, we found a cell-intrinsic dependency of DCs and Ly6C(+) monocytes on IFN-α receptor expression for EmGFP/IL-15 upregulation after vesicular stomatitis virus infection. In contrast, myeloid cells did not require the expression of MyD88 to upregulate EmGFP/IL-15 expression. These findings provide evidence of previously unappreciated regulation of IL-15 expression in myeloid lineages during homeostasis and following infection.

Asunto(s)

Células Dendríticas/metabolismo , Interleucina-15/biosíntesis , Transducción de Señal/inmunología , Animales , Separación Celular , Células Dendríticas/inmunología , Citometría de Flujo , Interleucina-15/inmunología , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Microscopía Confocal , Factor 88 de Diferenciación Mieloide/inmunología , Factor 88 de Diferenciación Mieloide/metabolismo , Receptor de Interferón alfa y beta/inmunología , Receptor de Interferón alfa y beta/metabolismo , Estomatitis Vesicular/inmunología