RESUMEN
OBJECTIVE: Platelet function has been intensively studied in the adult organism. However, little is known about the function and hemostatic capacity of platelets in the developing fetus as suitable in vivo models are lacking. APPROACH AND RESULTS: To examine fetal platelet function in vivo, we generated a fetal thrombosis model and investigated light/dye-induced thrombus formation by intravital microscopy throughout gestation. We observed that significantly less and unstable thrombi were formed at embryonic day (E) 13.5 compared with E17.5. Flow cytometry revealed significantly lower platelet counts in E13.5 versus E17.5 fetuses versus adult controls. In addition, fetal platelets demonstrated changed activation responses of surface adhesion molecules and reduced P-selectin content and mobilization. Interestingly, we also measured reduced levels of the integrin-activating proteins Kindlin-3, Talin-1, and Rap1 during fetal development. Consistently, fetal platelets demonstrated diminished spreading capacity compared with adults. Transfusion of adult platelets into the fetal circulation led to rapid platelet aggregate formation even in young fetuses. Yet, retrospective data analysis of a neonatal cohort demonstrated no correlation of platelet transfusion with closure of a persistent ductus arteriosus, a process reported to be platelet dependent. CONCLUSIONS: Taken together, we demonstrate an ontogenetic regulation of platelet function in vivo with physiologically low platelet numbers and hyporeactivity early during fetal development shedding new light on hemostatic function during fetal life.
Asunto(s)
Plaquetas/metabolismo , Hemostasis , Activación Plaquetaria , Trombosis/sangre , Animales , Moléculas de Adhesión Celular/sangre , Bases de Datos Factuales , Modelos Animales de Enfermedad , Conducto Arterioso Permeable/sangre , Femenino , Edad Gestacional , Proteínas Fluorescentes Verdes/genética , Proteínas Fluorescentes Verdes/metabolismo , Humanos , Recién Nacido , Recien Nacido Prematuro , Recién Nacido de muy Bajo Peso , Ratones Endogámicos C57BL , Ratones Transgénicos , Adhesividad Plaquetaria , Transfusión de Plaquetas , Nacimiento Prematuro/sangre , Estudios Retrospectivos , Transducción de Señal , Trombocitopenia/sangreRESUMEN
In adult mammals, leukocyte recruitment follows a well-defined cascade of adhesion events enabling leukocytes to leave the circulatory system and transmigrate into tissue. Currently, it is unclear whether leukocyte recruitment proceeds in a similar fashion during fetal development. Considering the fact that the incidence of neonatal sepsis increases dramatically with decreasing gestational age in humans, we hypothesized that leukocyte recruitment may be acquired only late during fetal ontogeny. To test this, we developed a fetal intravital microscopy model in pregnant mice and, using LysEGFP (neutrophil reporter) mice, investigated leukocyte recruitment during fetal development. We show that fetal blood neutrophils acquire the ability to roll and adhere on inflamed yolk sac vessels during late fetal development, whereas at earlier embryonic stages (before day E15), rolling and adhesion were essentially absent. Accordingly, flow chamber experiments showed that fetal EGFP(+) blood cells underwent efficient adhesion only when they were harvested on or after E15. Fluorescence-activated cell sorter analysis on EGFP(+) fetal blood cells revealed that surface expression of CXCR2 and less pronounced P-selectin glycoprotein ligand-1 (PSGL-1) begin to increase only late in fetal life. Taken together, our findings demonstrate that inflammation-induced leukocyte recruitment is ontogenetically regulated and enables efficient neutrophil trafficking only during late fetal life.
Asunto(s)
Movimiento Celular/inmunología , Sistema Inmunológico/embriología , Leucocitos/citología , Microvasos/embriología , Saco Vitelino/embriología , Animales , Adhesión Celular/inmunología , Eritroblastos/citología , Femenino , Sangre Fetal/citología , Proteínas Fluorescentes Verdes/metabolismo , Sistema Inmunológico/citología , Rodamiento de Leucocito/inmunología , Leucocitos/metabolismo , Glicoproteínas de Membrana/metabolismo , Ratones , Microvasos/citología , Microvasos/inmunología , Neutrófilos/citología , Neutrófilos/metabolismo , Selectina-P/metabolismo , Embarazo , Receptores de Interleucina-8B/metabolismo , Saco Vitelino/irrigación sanguínea , Saco Vitelino/citologíaRESUMEN
BACKGROUND: Lactoferrin (LF) is a pleiotropic glycoprotein that is found in bodily secretions and is postulated to enhance the gastrointestinal barrier and promote mucosal immunity. Thus, the ability of talactoferrin, an oral recombinant form of human LF, to limit gut injury and the production of biologically active gut-derived products was tested using a rat model of trauma-hemorrhagic shock (T/HS). METHODS: Male rats were orally dosed with vehicle or talactoferrin (1000 mg/kg, every day) for 5 d before being subjected to T/HS or trauma-sham shock (T/SS). Subsequently, rats were subjected to a laparotomy (trauma) and hemorrhagic shock (mean arterial pressure, 30-35 mm Hg × 90 min) or to T/SS, followed by resuscitation with their shed blood. Before inducing shock, the mesenteric lymphatic duct was catheterized for collection of mesenteric lymph. Four hours after the end of the shock or sham-shock period, rats were sacrificed, a segment of the distal ileum was collected for morphologic analysis, and lymph samples were processed and frozen. Subsequently, lymph samples were tested in several pharmacodynamic assays, including endothelial cell permeability, neutrophil respiratory burst activity, and red blood cell (RBC) deformability. Total white blood cell counts in lymph samples were also quantified. RESULTS: Pretreatment with talactoferrin reduced the incidence of T/HS-induced morphologic injury of ileum to T/SS levels. Post-T/HS lymph from vehicle-treated rats increased endothelial monolayer permeability and neutrophil priming for an augmented respiratory burst, and induced loss of RBC deformability, compared with T/SS groups. Talactoferrin pretreatment significantly reduced the biological activity of T/HS lymph on respiratory burst activity and RBC deformability, but had no effect on the lymph cell count or endothelial cell permeability. CONCLUSIONS: These results provide a proof of principle that prophylactic dosing of oral talactoferrin can potentially protect the gut in a T/HS model and limit the production of biologically active factors in rat gastrointestinal tissue subjected to ischemia-reperfusion-type injuries.
Asunto(s)
Íleon/lesiones , Lactoferrina/farmacología , Linfa/fisiología , Daño por Reperfusión/prevención & control , Choque Hemorrágico/tratamiento farmacológico , Administración Oral , Animales , Íleon/efectos de los fármacos , Laparotomía/efectos adversos , Linfa/efectos de los fármacos , Sistema Linfático/efectos de los fármacos , Sistema Linfático/fisiología , Masculino , Neutrófilos/efectos de los fármacos , Neutrófilos/fisiología , Ratas , Ratas Sprague-Dawley , Proteínas Recombinantes/farmacología , Daño por Reperfusión/etiología , Estallido Respiratorio/efectos de los fármacos , Choque Hemorrágico/etiología , Heridas y Lesiones/complicacionesRESUMEN
We present a novel approach for first-in-human (FIH) dose selection of the CD20xCD3 bispecific antibody, glofitamab, based on pharmacokinetic/pharmacodynamic (PKPD) assessment in cynomolgus monkeys to select a high, safe starting dose, with cytokine release (CR) as the PD endpoint. Glofitamab pharmacokinetics were studied in mice and cynomolgus monkeys; PKPD of IL-6, TNF-α and interferon-γ release following glofitamab, with/without obinutuzumab pretreatment (Gpt) was studied in cynomolgus monkeys. Potency differences for CR between cynomolgus monkeys and humans were determined by glofitamab incubation in whole blood of both species. The PKPD model for CR was translated to humans to project a starting dose that did not induce CR exceeding a clinically-predefined threshold. In cynomolgus monkeys, glofitamab showed a species-specific atypical high clearance, with and without B-cell debulking by Gpt. CR was related to glofitamab serum levels and B-cell counts. B-cell reduction by Gpt led to a marked decrease in CR. FIH starting dose (5 µg) was selected based on IL-6 release considering the markedly higher glofitamab in vitro potency in human vs monkey blood. This is a novel PKPD-based approach for selection of FIH starting dose for a CD20xCD3 bispecific antibody in B-cell lymphoma, evidenced in the glofitamab study, NP30179 (NCT03075696).
Asunto(s)
Anticuerpos Biespecíficos , Linfoma de Células B , Animales , Citocinas , Humanos , Interleucina-6 , Linfoma de Células B/tratamiento farmacológico , Linfoma de Células B/patología , Macaca fascicularis , RatonesRESUMEN
Lymphocytes home to peripheral lymph nodes (PLNs) via high endothelial venules (HEVs) in the subcortex and incrementally larger collecting venules in the medulla. HEVs express ligands for L-selectin, which mediates lymphocyte rolling. L-selectin counterreceptors in HEVs are recognized by mAb MECA-79, a surrogate marker for molecularly heterogeneous glycans termed peripheral node addressin. By contrast, we find that medullary venules express L-selectin ligands not recognized by MECA-79. Both L-selectin ligands must be fucosylated by alpha(1,3)-fucosyltransferase (FucT)-IV or FucT-VII as rolling is absent in FucT-IV+VII(-/-) mice. Intravital microscopy experiments revealed that MECA-79-reactive ligands depend primarily on FucT-VII, whereas MECA-79-independent medullary L-selectin ligands are regulated by FucT-IV. Expression levels of both enzymes paralleled these anatomical distinctions. The relative mRNA level of FucT-IV was higher in medullary venules than in HEVs, whereas FucT-VII was most prominent in HEVs and weak in medullary venules. Thus, two distinct L-selectin ligands are segmentally confined to contiguous microvascular domains in PLNs. Although MECA-79-reactive species predominate in HEVs, medullary venules express another ligand that is spatially, antigenically, and biosynthetically unique. Physiologic relevance for this novel activity in medullary microvessels is suggested by the finding that L-selectin-dependent T cell homing to PLNs was partly insensitive to MECA-79 inhibition.
Asunto(s)
Fucosiltransferasas/metabolismo , Selectina L/metabolismo , Ganglios Linfáticos/metabolismo , Animales , Antígenos de Superficie/inmunología , Secuencia de Bases , Cartilla de ADN , Citometría de Flujo , Selectina L/inmunología , Ligandos , Ganglios Linfáticos/enzimología , Proteínas de la Membrana , Ratones , Ratones Transgénicos , Reacción en Cadena de la Polimerasa de Transcriptasa InversaRESUMEN
A class of 3,5-diphenyl-1,2,4-oxadiazole based compounds have been identified as potent sphingosine-1-phosphate-1 (S1P1) receptor agonists with minimal affinity for the S1P2 and S1P3 receptor subtypes. Analogue 26 (S1P1 IC50 = 0.6 nM) has an excellent pharmacokinetics profile in the rat and dog and is efficacious in a rat skin transplant model, indicating that S1P3 receptor agonism is not a component of immunosuppressive efficacy.
Asunto(s)
Inmunosupresores/síntesis química , Oxadiazoles/síntesis química , Receptores de Lisoesfingolípidos/agonistas , Animales , Células CHO , Cricetinae , Cricetulus , Perros , Supervivencia de Injerto , Inmunosupresores/farmacocinética , Inmunosupresores/farmacología , Recuento de Linfocitos , Oxadiazoles/farmacocinética , Oxadiazoles/farmacología , Ensayo de Unión Radioligante , Ratas , Ratas Endogámicas Lew , Ratas Sprague-Dawley , Trasplante de Piel , Relación Estructura-ActividadRESUMEN
Attenuation of the immune response contributes to the high rate of neonatal infections, particularly in premature infants. Whereas our knowledge of innate immune functions in mature neonates is growing, little is known about the ontogeny of neutrophil recruitment. We investigated neutrophils and ECs in the course of gestation with respect to rolling and adhesive functions. With the use of microflow chambers, we demonstrate that the neutrophil's ability to roll and adhere directly correlates with gestational age. These adhesion-related abilities are very rare in extremely premature infants (<30 weeks of gestation), which may correlate with our observation of markedly reduced expression of PSGL-1 and Mac-1 on neutrophils in preterm infants. In parallel, the capacity of HUVECs to mediate neutrophil adhesion under flow increases with gestational age. In addition, HUVECs from extremely premature infants exerting the lowest ability to recruit adult neutrophils show a diminished up-regulation of E-selectin and ICAM-1. Finally, by following neutrophil function postnatally, we show that maturation of PMN recruitment proceeds equivalently during extra- and intrauterine development. Thus, PMN recruitment and EC adhesion-related functions are ontogenetically regulated in the fetus, which might contribute significantly to the high risk of life-threatening infections in premature infants.
Asunto(s)
Células Endoteliales/citología , Células Endoteliales/inmunología , Feto/citología , Feto/inmunología , Recién Nacido/inmunología , Neutrófilos/citología , Neutrófilos/inmunología , Adhesión Celular , Selectina E/inmunología , Selectina E/metabolismo , Femenino , Feto/embriología , Citometría de Flujo , Técnica del Anticuerpo Fluorescente , Edad Gestacional , Células Endoteliales de la Vena Umbilical Humana , Humanos , Recien Nacido Extremadamente Prematuro/inmunología , Recien Nacido Extremadamente Prematuro/metabolismo , Recien Nacido Prematuro , Molécula 1 de Adhesión Intercelular/inmunología , Molécula 1 de Adhesión Intercelular/metabolismo , Rodamiento de Leucocito , Masculino , Infiltración Neutrófila/inmunología , Selectina-P/inmunología , Selectina-P/metabolismoAsunto(s)
Adhesión Celular/fisiología , Movimiento Celular/fisiología , Microscopía por Video/métodos , Metástasis de la Neoplasia/fisiopatología , Proteínas de Neoplasias/fisiología , Proteínas Tirosina Quinasas/fisiología , Animales , Técnicas de Cultivo de Célula/instrumentación , Trasplante de Células , Quimiotaxis/fisiología , Femenino , Humanos , Procesamiento de Imagen Asistido por Computador , Inyecciones , Masculino , Ratones , Ratones Endogámicos C57BL , Microscopía/métodos , Microscopía por Video/instrumentaciónRESUMEN
A series of 3-arylpropionic acids were synthesized as S1P1 receptor agonists. Structure-activity relationship studies on the pendant phenyl ring revealed several structural features offering selectivity of S1P1 binding against S1P2-5. These highly selective S1P1 agonists induced peripheral blood lymphocyte lowering in mice and one of them was found to be efficacious in a rat skin transplantation model, supporting that S1P1 agonism is primarily responsible for the immunosuppressive efficacy observed in preclinical animal models.
Asunto(s)
Inmunosupresores/farmacología , Fenilpropionatos/síntesis química , Fenilpropionatos/farmacología , Receptores de Lisoesfingolípidos/agonistas , Animales , Células CHO , Cricetinae , Ligandos , Recuento de Linfocitos/veterinaria , Ratones , Ratas , Trasplante de Piel , Relación Estructura-ActividadRESUMEN
The sphingosine-1-phosphate (S1P) receptor agonist, phosphorylated FTY720 (FTY-P), causes lymphopenia, lymphocyte sequestration in mesenteric lymph nodes (MLNs), and immunosuppression. Using multiple techniques to analyze MLN cells harvested from mice treated with S1P receptor agonists, we saw a redistribution of lymphocytes out of nodal sinuses and an expansion of follicles. Although changes in circulating monocytes were not observed with overnight exposure to FTY720, we saw a significant increase in S1P receptor 1 (S1P1)-expressing CD68+ macrophages in subcapsular sinuses of FTY-P-treated MLNs. This was confirmed by quantitative analysis of F4/80+ cells in MLN suspensions. The sinus volume and number of S1P1-positive cells within sinuses were also increased by FTY-P. High endothelial venules and lymphatic endothelium expressed high levels of S1P1, and treatment with FTY-P resulted in intense staining and colocalization of CD31, beta-catenin, and zona occludens 1 in junctions between sinus cells. Transmission electron microscopy showed that FTY-P greatly reduced lymphocyte microvilli and increased cell-cell contacts in the parenchyma. Immunoelectron microscopy revealed that intranodal lymphocytes lacked surface expression of S1P1, whereas S1P1 was evident on the surface and within the cytoplasm of macrophages, endothelial cells, and stromal cells. This subcellular pattern of intranodal receptor distribution was unchanged by treatment with FTY-P. We conclude that S1P1 agonists have profound effects on macrophages and endothelial cells, in addition to inducing lymphopenia.
Asunto(s)
Inmunosupresores/farmacología , Ganglios Linfáticos/inmunología , Linfocitos/inmunología , Macrófagos/inmunología , Glicoles de Propileno/farmacología , Receptores de Lisoesfingolípidos/inmunología , Animales , Comunicación Celular/inmunología , Células Endoteliales/efectos de los fármacos , Células Endoteliales/inmunología , Células Endoteliales/ultraestructura , Endotelio Linfático/efectos de los fármacos , Endotelio Linfático/ultraestructura , Endotelio Vascular/efectos de los fármacos , Endotelio Vascular/ultraestructura , Femenino , Clorhidrato de Fingolimod , Técnica del Anticuerpo Fluorescente , Ganglios Linfáticos/efectos de los fármacos , Linfocitos/efectos de los fármacos , Linfocitos/metabolismo , Macrófagos/efectos de los fármacos , Macrófagos/metabolismo , Mesenterio/inmunología , Ratones , Ratones Endogámicos C57BL , Microscopía Electrónica de Transmisión , Microscopía Inmunoelectrónica , Fosforilación , Receptores de Lisoesfingolípidos/efectos de los fármacos , Receptores de Lisoesfingolípidos/metabolismo , Esfingosina/análogos & derivados , Uniones Estrechas/inmunología , Uniones Estrechas/ultraestructuraRESUMEN
Sphingosine-1-phosphate (S1P) and its receptor S1P1 control T-cell egress from thymus and secondary lymphoid organs (SLOs). To further define the role of S1P1 in lymphocyte trafficking, we performed adoptive transfer experiments and intravital microscopy (IVM) using both S1P1-/- lymphocytes and recipient wild-type (WT) mice treated with FTY720, an immunosuppressant that downmodulates S1P receptors. S1P1 deficiency and FTY720 caused rapid disappearance of T cells from blood, prolonged retention in SLOs, and accumulation in bone marrow, but did not alter interstitial T-cell motility in peripheral lymph nodes (PLNs) as assessed by multiphoton IVM. However, S1P1-/- lymphocytes displayed reduced short-term homing to PLNs due to attenuated integrin-mediated firm arrest in high endothelial venules (HEVs). By contrast, S1P1-/- T cells homed normally to Peyer patches (PPs), whereas S1P1-/- B cells had a marked defect in homing to PPs and arrested poorly in PP HEVs. Therefore, S1P1 not only controls lymphocyte egress from SLOs, but also facilitates in a tissue- and subset-specific fashion integrin activation during homing. Interestingly, FTY720 treatment enhanced accumulation of both S1P1 sufficient and S1P1-/- T cells in PPs by enhancing integrin-mediated arrest in HEVs. Thus, FTY720 exerts unique effects on T-cell traffic in PPs that are independent of T-cell-expressed S1P1.
Asunto(s)
Quimiotaxis de Leucocito/efectos de los fármacos , Inmunosupresores/farmacología , Lisofosfolípidos/fisiología , Glicoles de Propileno/farmacología , Esfingosina/análogos & derivados , Linfocitos T/fisiología , Traslado Adoptivo , Animales , Quimiotaxis de Leucocito/fisiología , Clorhidrato de Fingolimod , Inmunosupresores/inmunología , Integrinas/metabolismo , Ganglios Linfáticos , Vasos Linfáticos , Recuento de Linfocitos , Linfocitos , Lisofosfolípidos/deficiencia , Lisofosfolípidos/inmunología , Ratones , Ratones Noqueados , Microscopía por Video , Ganglios Linfáticos Agregados , Glicoles de Propileno/inmunología , Esfingosina/deficiencia , Esfingosina/inmunología , Esfingosina/fisiología , Linfocitos T/efectos de los fármacosRESUMEN
Nonirradiated bone marrow (BM) venules and sinusoids in murine skull support hematopoietic progenitor cell (HPC) rolling through constitutively expressed endothelial (P- and E-) selectins and VCAM-1. Using intravital microscopy, we tested whether host conditioning with total body irradiation (TBI) changes the molecular mechanisms by which murine HPCs from fetal livers (FL) interact with BM endothelial cells. Although a high dose of TBI did not affect the overall frequency of HPC rolling in BM microvessels, the underlying molecular mechanisms differed from those in nonirradiated BM. TBI induced VCAM-1 up-regulation in BM microvessels, whereas P-selectin expression was reduced and the low baseline level of E-selectin remained unchanged. Only the administration of anti-VCAM-1, but not anti-P- or -E-selectin monoclonal antibodies, decreased FL HPC rolling. Rolling was frequently followed by firm arrest (sticking), even in nonirradiated BM microvessels in which sticking was entirely pertussis toxin-insensitive-that is, Galpha(i)-coupled signaling events (eg, through chemokines) were apparently not required. TBI increased the frequency of sticking FL HPC. This irradiation-induced additional sticking was reversed when FL HPCs were pretreated with pertussis toxin, suggesting that TBI induced elevated expression of a Galpha(i)-protein-coupled chemotactic signal in the BM. This chemoattractant was probably distinct from SDF-1alpha because, unlike adult HPCs, FL HPCs (day 11 of gestation) responded poorly to SDF-1alpha in vitro. These results demonstrate that TBI induces profound changes in the expression of endothelial traffic molecules in the BM, and they indicate that FL HPCs can home to the BM in the absence of SDF-1alpha and other Galpha(i)-protein-coupled signals.
Asunto(s)
Células de la Médula Ósea/efectos de la radiación , Endotelio Vascular/fisiología , Células Madre Hematopoyéticas/efectos de la radiación , Animales , Anticuerpos Monoclonales/farmacología , Células de la Médula Ósea/citología , Células de la Médula Ósea/fisiología , Huesos , Quimiotaxis/fisiología , Quimiotaxis/efectos de la radiación , Relación Dosis-Respuesta en la Radiación , Selectina E/análisis , Endotelio Vascular/efectos de la radiación , Femenino , Células Madre Hematopoyéticas/fisiología , Hemodinámica/efectos de la radiación , Masculino , Ratones , Ratones Endogámicos C57BL , Selectina-P/análisis , Cráneo , Molécula 1 de Adhesión Celular Vascular/análisisRESUMEN
We describe a lethal neonatal form of carnitine palmitoyltransferase II (CPT II) deficiency with compound heterozygosity for 2 truncation mutations (Q413fs and 109AGC --> GCAGC). A new phenotype for a severe late infantile form of CPT II deficiency with hypoglycemia is associated with compound heterozygosity for the severe Q413fs mutation and a mild point mutation (P50H).
Asunto(s)
Carnitina O-Palmitoiltransferasa/deficiencia , Deleción Cromosómica , Mutación Puntual , Análisis Mutacional de ADN , Heterocigoto , Humanos , Hipoglucemia/diagnóstico , Hipoglucemia/genética , Lactante , Masculino , FenotipoRESUMEN
FTY720 (2-amino-[2-(4-octylphenyl) ethyl]-1,3-propanediol hydrochloride) is an immunosuppressive agent that inhibits allograft rejection. We recently demonstrated that FTY-phosphate, the active metabolite of FTY720, acts as a full agonist for sphingosine-1-phosphate (S1P) receptors. Furthermore, activation of S1P receptors with their natural ligand, S1P, as well as pharmacological ligands leads to lymphopenia, probably due to sequestration of lymphocytes in secondary lymphoid organs. In the present study we used a local Ag-challenged mouse model to examine the effects of FTY720 on T cell activation in the draining lymph node (DLN) and on the release of activated T cells to the peripheral blood compartment. We showed that the number of Ag-activated CD4(+) T cells in the DLN after injection of Ag and CFA into a footpad was dramatically reduced after FTY720 treatment. However, T cell proliferation, both in vitro and in vivo, was not impaired by FTY720. Our results suggest that the reduced efficiency of T cell responses in the DLN in response to a local Ag is probably due to a defective recirculation of naive T cells caused by FTY720 treatment. Furthermore, we found that the numbers of naive and Ag-activated CD4(+) T cells in the peripheral blood of Ag-challenged mice were equally reduced with FTY720 treatment, suggesting that both T cell subsets are sequestered in the DLNs. Thus, FTY720 induces immunosuppression through inhibition of both the recirculation of naive T cells and the release of Ag-activated T cells from the DLN to lymph and to the blood compartment.
Asunto(s)
Antígenos/farmacología , Linfocitos T CD4-Positivos/inmunología , Movimiento Celular/inmunología , Interfase/inmunología , Activación de Linfocitos , Ovalbúmina/farmacología , Receptores de Superficie Celular/agonistas , Receptores Acoplados a Proteínas G , Esfingosina/metabolismo , Animales , Antígenos/administración & dosificación , Bromodesoxiuridina/metabolismo , Linfocitos T CD4-Positivos/efectos de los fármacos , Linfocitos T CD4-Positivos/trasplante , División Celular/efectos de los fármacos , División Celular/inmunología , Movimiento Celular/efectos de los fármacos , Epítopos de Linfocito T/inmunología , Clorhidrato de Fingolimod , Citometría de Flujo , Fluoresceínas/metabolismo , Colorantes Fluorescentes/metabolismo , Inhibidores de Crecimiento/administración & dosificación , Inhibidores de Crecimiento/sangre , Inhibidores de Crecimiento/farmacología , Inmunosupresores/administración & dosificación , Inmunosupresores/sangre , Inmunosupresores/farmacología , Inyecciones Subcutáneas , Interfase/efectos de los fármacos , Ganglios Linfáticos/citología , Ganglios Linfáticos/efectos de los fármacos , Ganglios Linfáticos/inmunología , Activación de Linfocitos/efectos de los fármacos , Prueba de Cultivo Mixto de Linfocitos , Depleción Linfocítica , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Ratones Transgénicos , Ovalbúmina/administración & dosificación , Glicoles de Propileno/administración & dosificación , Glicoles de Propileno/sangre , Glicoles de Propileno/farmacología , Receptores Lisofosfolípidos , Succinimidas/metabolismo , Células TH1/efectos de los fármacos , Células TH1/inmunologíaRESUMEN
Blood lymphocyte numbers, essential for the development of efficient immune responses, are maintained by recirculation through secondary lymphoid organs. We show that lymphocyte trafficking is altered by the lysophospholipid sphingosine-1-phosphate (S1P) and by a phosphoryl metabolite of the immunosuppressive agent FTY720. Both species were high-affinity agonists of at least four of the five S1P receptors. These agonists produce lymphopenia in blood and thoracic duct lymph by sequestration of lymphocytes in lymph nodes, but not spleen. S1P receptor agonists induced emptying of lymphoid sinuses by retention of lymphocytes on the abluminal side of sinus-lining endothelium and inhibition of egress into lymph. Inhibition of lymphocyte recirculation by activation of S1P receptors may result in therapeutically useful immunosuppression.