RESUMEN
The basalts of the 2021 Fagradalsfjall eruption were the first erupted on the Reykjanes Peninsula in 781 years and offer a unique opportunity to determine the composition of the mantle underlying Iceland, in particular its oxygen isotope composition (δ18O values). The basalts show compositional variations in Zr/Y, Nb/Zr and Nb/Y values that span roughly half of the previously described range for Icelandic basaltic magmas and signal involvement of Icelandic plume (OIB) and Enriched Mid-Ocean Ridge Basalt (EMORB) in magma genesis. Here we show that Fagradalsfjall δ18O values are invariable (mean δ18O = 5.4 ± 0.3 2 SD, N = 47) and indistinguishable from "normal" upper mantle, in contrast to significantly lower δ18O values reported for erupted materials elsewhere in Iceland (e.g., the 2014-2015 eruption at Holuhraun, Central Iceland). Thus, despite differing trace element characteristics, the melts that supplied the Fagradalsfjall eruption show no evidence for 18O-depleted mantle or interaction with low-δ18O crust and may therefore represent a useful mantle reference value in this part of the Icelandic plume system.
RESUMEN
We examined tolerance mechanisms in patients receiving HLA-mismatched combined kidney-bone marrow transplantation (CKBMT) that led to transient chimerism under a previously published nonmyeloablative conditioning regimen (Immune Tolerance Network study 036). Polychromatic flow cytometry and high-throughput sequencing of T cell receptor-ß hypervariable regions of DNA from peripheral blood regulatory T cells (Tregs) and CD4 non-Tregs revealed marked early enrichment of Tregs (CD3+ CD4+ CD25high CD127low Foxp3+ ) in blood that resulted from peripheral proliferation (Ki67+ ), possibly new thymic emigration (CD31+ ), and, in one tolerant subject, conversion from non-Tregs. Among recovering conventional T cells, central memory CD4+ and CD8+ cells predominated. A large proportion of the T cell clones detected in posttransplantation biopsy specimens by T cell receptor sequencing were detected in the peripheral blood and were not donor-reactive. Our results suggest that enrichment of Tregs by new thymic emigration and lymphopenia-driven peripheral proliferation in the early posttransplantation period may contribute to tolerance after CKBMT. Further, most conventional T cell clones detected in immunologically quiescent posttransplantation biopsy specimens appear to be circulating cells in the microvasculature rather than infiltrating T cells.
Asunto(s)
Trasplante de Médula Ósea , Supervivencia de Injerto/inmunología , Tolerancia Inmunológica/inmunología , Trasplante de Riñón , Linfocitos T Reguladores/inmunología , Tolerancia al Trasplante/inmunología , Femenino , Humanos , Masculino , Receptores de Antígenos de Linfocitos T/inmunología , Receptores de Antígenos de Linfocitos T/metabolismo , Quimera por Trasplante/inmunologíaRESUMEN
BACKGROUND AND PURPOSE: Infants with congenital diaphragmatic hernia are reported to have evidence of brain MR imaging abnormalities. Our study aimed to identify perinatal clinical factors in infants with congenital diaphragmatic hernia that are associated with evidence of brain injury on MR imaging performed before hospital discharge. MATERIALS AND METHODS: MRIs performed before hospital discharge in infants with congenital diaphragmatic hernia were scored for brain injury by 2 pediatric neuroradiologists. Perinatal variables and clinical variables from the neonatal intensive care unit stay were analyzed for potential associations with brain MR imaging findings. RESULTS: Fifty-three infants with congenital diaphragmatic hernia (31 boys) were included. At least 1 abnormality was seen on MR imaging in 32 infants (60%). The most common MR imaging findings were enlarged extra-axial spaces (36%), intraventricular hemorrhage (23%), ventriculomegaly (19%), white matter injury (17%), and cerebellar hemorrhage (17%). The MR imaging brain injury score was associated with extracorporeal membrane oxygenation (P = .0001), lack of oral feeding at discharge (P = .012), use of inotropes (P = .027), and gastrostomy tube placement before hospital discharge (P = .024). The MR imaging brain injury score was also associated with a large diaphragmatic defect size (P = .011). CONCLUSIONS: Most infants with congenital diaphragmatic hernia have at least 1 abnormality identified on MR imaging of the brain performed before discharge. The main predictors of brain injury in this population are a requirement for extracorporeal membrane oxygenation, large diaphragmatic defect size, and lack of oral feeding at discharge.
Asunto(s)
Lesiones Encefálicas/diagnóstico por imagen , Hernias Diafragmáticas Congénitas/diagnóstico por imagen , Hemorragia Encefálica Traumática/diagnóstico por imagen , Diafragma/anomalías , Oxigenación por Membrana Extracorpórea/efectos adversos , Femenino , Humanos , Lactante , Recién Nacido , Recien Nacido Prematuro , Hemorragias Intracraneales/diagnóstico por imagen , Intubación Gastrointestinal/efectos adversos , Imagen por Resonancia Magnética , Masculino , Embarazo , Sustancia Blanca/diagnóstico por imagenRESUMEN
Tolerance of allografts achieved in mice via stable mixed hematopoietic chimerism relies essentially on continuous elimination of developing alloreactive T cells in the thymus (central deletion). Conversely, while only transient mixed chimerism is observed in nonhuman primates and patients, it is sufficient to ensure tolerance of kidney allografts. In this setting, it is likely that tolerance depends on peripheral regulatory mechanisms rather than thymic deletion. This implies that, in primates, upsetting the balance between inflammatory and regulatory alloimmunity could abolish tolerance and trigger the rejection of previously accepted renal allografts. In this study, six monkeys that were treated with a mixed chimerism protocol and had accepted a kidney allograft for periods of 1-10 years after withdrawal of immunosuppression received subcutaneous injections of IL-2 cytokine (0.6-3 × 10(6) IU/m(2) ). This resulted in rapid rejection of previously tolerated renal transplants and was associated with an expansion and reactivation of alloreactive pro-inflammatory memory T cells in the host's lymphoid organs and in the graft. This phenomenon was prevented by anti-CD8 antibody treatment. Finally, this process was reversible in that cessation of IL-2 administration aborted the rejection process and restored normal kidney graft function.
Asunto(s)
Rechazo de Injerto/etiología , Interleucina-2/administración & dosificación , Fallo Renal Crónico/cirugía , Trasplante de Riñón , Complicaciones Posoperatorias , Quimera por Trasplante/inmunología , Tolerancia al Trasplante/inmunología , Animales , Trasplante de Médula Ósea , Quimerismo , Tasa de Filtración Glomerular , Rechazo de Injerto/tratamiento farmacológico , Supervivencia de Injerto , Inyecciones Subcutáneas , Pruebas de Función Renal , Macaca fascicularis , Ratones , Factores de Riesgo , Acondicionamiento Pretrasplante , Trasplante HomólogoRESUMEN
Blood chimerism has been reported sporadically among visceral transplant recipients, mostly in association with graft-vs-host disease (GVHD). We hypothesized that a higher degree of mixed chimerism would be observed in multivisceral (MVTx) than in isolated intestinal (iITx) and isolated liver transplant (iLTx) recipients, regardless of GVHD. We performed a longitudinal prospective study investigating multilineage blood chimerism with flow cytometry in 5 iITx and 4 MVTx recipients up to one year posttransplant. Although only one iITx patient experienced GVHD, T cell mixed chimerism was detected in 8 out of 9 iITx/MVTx recipients. Chimerism was significantly lower in the four subjects who displayed early moderate to severe rejection. Pre-formed high-titer donor-specific antibodies, bound in vivo to the circulating donor cells, were associated with an accelerated decline in chimerism. Blood chimerism was also studied in 10 iLTx controls. Among nonsensitized patients, MVTx recipients exhibited greater T and B cell chimerism than either iITx or iLTx recipients. Myeloid lineage chimerism was present exclusively among iLTx and MVTx (6/13) recipients, suggesting that its presence required the hepatic allograft. Our study demonstrates, for the first time, frequent T cell chimerism without GVHD following visceral transplantation and a possible relationship with reduced rejection rate in MVTx recipients.
Asunto(s)
Rechazo de Injerto/inmunología , Enfermedad Injerto contra Huésped/inmunología , Intestinos/trasplante , Trasplante de Hígado , Linfocitos T/inmunología , Quimera por Trasplante/inmunología , Adolescente , Adulto , Niño , Preescolar , Femenino , Citometría de Flujo , Estudios de Seguimiento , Rechazo de Injerto/sangre , Enfermedad Injerto contra Huésped/sangre , Humanos , Lactante , Masculino , Persona de Mediana Edad , Estudios Prospectivos , Quimera por Trasplante/sangre , Adulto JovenRESUMEN
Preexisting serum antibodies have long been associated with graft loss in transplant recipients. While most studies have focused on HLA-specific antibodies, the contribution of non-HLA-reactive antibodies has been largely overlooked. We have recently characterized mAbs secreted by B cell clones derived from kidney allograft recipients with rejection that bind to apoptotic cells. Here, we assessed the presence of such antibodies in pretransplant serum from 300 kidney transplant recipients and examined their contribution to the graft outcomes. Kaplan-Meier survival analysis revealed that patients with high pretransplant IgG reactivity to apoptotic cells had a significantly increased rate of late graft loss. The effect was only apparent after approximately 1 year posttransplant. Moreover, the association between pretransplant IgG reactivity to apoptotic cells and graft loss was still significant after excluding patients with high reactivity to HLA. This reactivity was almost exclusively mediated by IgG1 and IgG3 with complement fixing and activating properties. Overall, our findings support the view that IgG reactive to apoptotic cells contribute to presensitization. Taking these antibodies into consideration alongside anti-HLA antibodies during candidate evaluation would likely improve the transplant risk assessment.
Asunto(s)
Apoptosis/inmunología , Rechazo de Injerto/etiología , Supervivencia de Injerto , Antígenos de Histocompatibilidad Clase I/inmunología , Inmunoglobulina G/sangre , Fallo Renal Crónico/mortalidad , Trasplante de Riñón/efectos adversos , Aloinjertos , Ensayo de Inmunoadsorción Enzimática , Femenino , Estudios de Seguimiento , Rechazo de Injerto/diagnóstico , Rechazo de Injerto/mortalidad , Humanos , Células Jurkat , Fallo Renal Crónico/cirugía , Masculino , Persona de Mediana Edad , Pronóstico , Factores de Riesgo , Tasa de SupervivenciaRESUMEN
We report here the long-term results of HLA-mismatched kidney transplantation without maintenance immunosuppression (IS) in 10 subjects following combined kidney and bone marrow transplantation. All subjects were treated with nonmyeloablative conditioning and an 8- to 14-month course of calcineurin inhibitor with or without rituximab. All 10 subjects developed transient chimerism, and in seven of these, IS was successfully discontinued for 4 or more years. Currently, four subjects remain IS free for periods of 4.5-11.4 years, while three required reinstitution of IS after 5-8 years due to recurrence of original disease or chronic antibody-mediated rejection. Of the 10 renal allografts, three failed due to thrombotic microangiopathy or rejection. When compared with 21 immunologically similar living donor kidney recipients treated with conventional IS, the long-term IS-free survivors developed significantly fewer posttransplant complications. Although most recipients treated with none or two doses of rituximab developed donor-specific antibody (DSA), no DSA was detected in recipients treated with four doses of rituximab. Although further revisions of the current conditioning regimen are planned in order to improve consistency of the results, this study shows that long-term stable kidney allograft survival without maintenance IS can be achieved following transient mixed chimerism induction.
Asunto(s)
Trasplante de Médula Ósea , Supervivencia de Injerto/inmunología , Terapia de Inmunosupresión , Enfermedades Renales/cirugía , Trasplante de Riñón , Complicaciones Posoperatorias , Tolerancia al Trasplante/inmunología , Adulto , Femenino , Estudios de Seguimiento , Humanos , Inmunosupresores/uso terapéutico , Isoanticuerpos/sangre , Enfermedades Renales/inmunología , Masculino , Persona de Mediana Edad , Pronóstico , Quimera por Trasplante , Acondicionamiento Pretrasplante , Trasplante Homólogo , Adulto JovenRESUMEN
Antibody-mediated rejection (ABMR) represents a significant clinical challenge for solid organ transplantation. Mechanistic understanding of ABMR is incomplete and diagnostic accuracy for ABMR is limited, and as a result, targeted treatment remains elusive and new treatment modalities are difficult to validate. Three hundred twenty-six participants from 15 countries met for the first Cutting Edge of Transplantation (CEOT) symposium organized by the American Society of Transplantation (AST) in Chandler, Arizona, February 14-16, 2013. During the 3-day interactive symposium, presentations, moderated poster sessions and round table discussions addressed cutting edge knowledge of B and plasma cell biology, mechanisms of antibody-mediated tissue injury, advances and limitations in ABMR diagnostics, as well as current and potential new treatment options for ABMR. The outcome of the meeting identified the following unmet needs for: (a) improved understanding of the regulation of B cell maturation and antibody response to enable targeted therapies; (b) more precise diagnostics of ABMR, including molecular pathology, risk stratification by sensitive antibody testing and monitoring of treatment effects; and (c) innovative multicenter trial designs that enhance observational power, in particular, in assessing synergistic multimodality therapies with reduced toxicities.
Asunto(s)
Formación de Anticuerpos/inmunología , Linfocitos B/inmunología , Rechazo de Injerto/inmunología , Isoanticuerpos/inmunología , Trasplante de Órganos , Informe de Investigación , Rechazo de Injerto/prevención & control , HumanosRESUMEN
Antibody mediated rejection (AMR) is associated with a variety of graft-reactive antibodies following kidney transplant. To characterize these antibodies, we immortalized 107 B cell clones from a patient with AMR. In a previous study, we showed that six clones were reacting to multiple self-antigens as well as to HLA and MICA for two of them, thus displaying a pattern of polyreactivity. We show here that all six polyreactive clones also reacted to apoptotic but not viable cells. More generally we observed a nearly perfect overlap between polyreactivity and reactivity to apoptotic cells. Functionally, polyreactive antibodies can activate complement, resulting in the deposition of C3d and C4d at the surface of target cells. Testing the serum of 88 kidney transplant recipients revealed a significantly higher IgG reactivity to apoptotic cells in AMR patients than in patients with stable graft function. Moreover, total IgG purified from AMR patients had increased complement activating properties compared to IgG from non-AMR patients. Overall, our studies show the development of polyreactive antibodies cross-reactive to apoptotic cells during AMR. Further studies are now warranted to determine their contribution to the detection of C4d in graft biopsies as well as their role in the pathophysiology of AMR.
Asunto(s)
Apoptosis/fisiología , Autoanticuerpos/sangre , Activación de Complemento/inmunología , Complemento C4b/inmunología , Rechazo de Injerto/inmunología , Trasplante de Riñón , Fragmentos de Péptidos/inmunología , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Western Blotting , Estudios de Casos y Controles , Ensayo de Inmunoadsorción Enzimática , Femenino , Técnica del Anticuerpo Fluorescente , Humanos , Inmunidad Humoral , Inmunoglobulina G/sangre , Inmunoglobulina G/inmunología , Persona de Mediana Edad , Trasplante Homólogo , Adulto JovenRESUMEN
Antibody rejection is often accompanied by nondonor HLA specific antibodies (NDSA) and self-reactive antibodies that develop alongside donor-specific antibodies (DSA). To determine the source of these antibodies, we immortalized 107 B-cell clones from a kidney transplant recipient with humoral rejection. Two of these clones reacted to HLA class I or MICA. Both clones were also reactive to self-antigens and a lysate of a kidney cell line, hence revealing a pattern of polyreactivity. Monoclonality was verified by the identification of a single rearranged immunoglobulin heavy chain variable region (VH) sequence for each clone. By tracking their unique CDR3 sequence, we found that one such polyreactive clone was highly expanded in the patient blood, representing ~0.2% of circulating B cells. The VH sequence of this clone showed evidence of somatic mutations that were consistent with its memory phenotype and its expansion. Lastly, the reactivity of the expanded polyreactive B-cell clone was found in the patient serum at time of rejection. In conclusion, we provide here proof of principle at the clonal level that human antibodies can cross-react to HLA and self. Our findings strongly suggest that polyreactive antibodies contribute to DSA, NDSA as well as autoantibodies, in transplant recipients.
Asunto(s)
Linfocitos B/inmunología , Rechazo de Injerto/inmunología , Antígenos HLA/inmunología , Trasplante de Riñón/inmunología , Reacciones Cruzadas , Técnica del Anticuerpo Fluorescente , HumanosRESUMEN
Chronic humoral rejection (CHR) is an important cause of late graft failures following kidney transplantation. Overall, the pathophysiology of CHR is poorly understood. Matrix metalloproteinase-2 (MMP-2), a type IV collagenase, has been implicated in chronic kidney disease and allograft rejection in previous studies. We examined the presence of MMP-2 in allograft biopsies and in the urine of kidney transplant recipients with CHR. MMP-2 staining was detected by immunohistochemistry in podocytes for all CHR patients but less frequently in patients with other renal complications. Urinary MMP-2 levels were also significantly higher in CHR patients (median 4942 pg/mL, N = 27) compared to non-CHR patients (median 598 pg/mL, N = 65; p < 0.001). Elevated urinary MMP-2 correlated with higher levels of proteinuria in both CHR and non-CHR patients. Longitudinal analysis indicated that increase in urine MMP-2 coincided with initial diagnosis of CHR as documented by the biopsies. Using an enzymatic assay, we demonstrated that MMP-2 was present in its active form in the urine of patients with CHR. Overall, our findings associate MMP-2 with glomerular injury as well as interstitial fibrosis and tubular atrophy observed in patients with CHR.
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Rechazo de Injerto/patología , Trasplante de Riñón/efectos adversos , Metaloproteinasa 2 de la Matriz/metabolismo , Metaloproteinasa 2 de la Matriz/orina , Podocitos/enzimología , Femenino , Fibrosis , Rechazo de Injerto/inmunología , Humanos , Enfermedades Renales/patología , Glomérulos Renales/patología , Trasplante de Riñón/inmunología , Masculino , Persona de Mediana Edad , Proteinuria/complicacionesRESUMEN
Five patients with end-stage kidney disease received combined kidney and bone marrow transplants from HLA haploidentical donors following nonmyeloablative conditioning to induce renal allograft tolerance. Immunosuppressive therapy was successfully discontinued in four patients with subsequent follow-up of 3 to more than 6 years. This allograft acceptance was accompanied by specific T-cell unresponsiveness to donor antigens. However, two of these four patients showed evidence of de novo antibodies reactive to donor antigens between 1 and 2 years posttransplant. These humoral responses were characterized by the presence of donor HLA-specific antibodies in the serum with or without the deposition of the complement molecule C4d in the graft. Immunofluorescence staining, ELISA assays and antibody profiling using protein microarrays demonstrated the co-development of auto- and alloantibodies in these two patients. These responses were preceded by elevated serum BAFF levels and coincided with B-cell reconstitution as revealed by a high frequency of transitional B cells in the periphery. To date, these B cell responses have not been associated with evidence of humoral rejection and their clinical significance is still unclear. Overall, our findings showed the development of B-cell allo- and autoimmunity in patients with T-cell tolerance to the donor graft.
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Linfocitos B/inmunología , Trasplante de Médula Ósea/métodos , Tolerancia Inmunológica , Trasplante de Riñón/métodos , Linfocitos T/inmunología , Línea Celular , Complemento C4b/química , Ensayo de Inmunoadsorción Enzimática/métodos , Rechazo de Injerto/inmunología , Antígenos HLA/química , Humanos , Sistema Inmunológico , Microscopía Fluorescente/métodos , Fragmentos de Péptidos/química , Análisis por Matrices de Proteínas , Factores de TiempoRESUMEN
Bortezomib is a proteasome inhibitor for the treatment of relapsed/refractory multiple myeloma (MM). Mechanisms of resistance to Bortezomib are undefined. Myeloid cell leukemia-1 (Mcl-1) is an antiapoptotic protein, which protects tumor cells against spontaneous and chemotherapy-induced apoptosis. In MM, specific downregulation of Mcl-1 induces apoptosis. Here, we examined the role of Mcl-1 in Bortezomib- and doxorubicin-induced apoptosis. We demonstrate that Bortezomib, but not doxorubicin, triggers caspase-dependent generation of a 28 kDa Mcl-1-fragment, in several MM cell lines, including MM.1S cells. Conversely, transient transfection of MM.1S cells with a previously reported 28 kDa Mcl-1(128-350) fragment, but not with the Mcl-1(1-127) fragment, induces apoptosis. Therefore, both downregulation of full-length antiapoptotic Mcl-1, as well as Bortezomib-induced generation of Mcl-1(128-350) cleaved protein, contribute to MM cell apoptosis. To verify further these findings, we next compared effects triggered by Bortezomib, doxorubicin and melphalan in Mcl-1(wt/wt) and Mcl-1(Delta/null) murine embryonic fibroblasts (MEFs). Our results show that Bortezomib, but not doxorubicin or melphalan, triggers Mcl-1 cleavage in Mcl-1(wt/wt), but not Mcl-1(Delta/null) MEFs and induces sub-G(1) phase cells; caspase-3 and -9, and PARP cleavage as well as morphological signs of apoptosis. Taken together, these results support an important role of Mcl-1 and a Mcl-1 fragment in Bortezomib-induced cell death in general, and in MM in particular. To prevent relapse of MM in patients treated with Bortezomib, we therefore recommend the combination of Bortezomib with agents that induce MM cell death independent of Mcl-1.
Asunto(s)
Antineoplásicos/farmacología , Apoptosis , Ácidos Borónicos/farmacología , Mieloma Múltiple/enzimología , Proteínas de Neoplasias/metabolismo , Inhibidores de Proteasas/farmacología , Proteínas Proto-Oncogénicas c-bcl-2/metabolismo , Pirazinas/farmacología , Animales , Bortezomib , Inhibidores de Caspasas , Caspasas/metabolismo , Línea Celular Tumoral , Doxorrubicina/farmacología , Humanos , Melfalán/farmacología , Ratones , Proteína 1 de la Secuencia de Leucemia de Células Mieloides , Proteínas de Neoplasias/antagonistas & inhibidores , Proteínas de Neoplasias/genética , Poli(ADP-Ribosa) Polimerasas/metabolismo , Proteínas Proto-Oncogénicas c-bcl-2/antagonistas & inhibidores , Proteínas Proto-Oncogénicas c-bcl-2/genética , ARN Interferente Pequeño/farmacología , Regulación hacia ArribaRESUMEN
Interleukin-12 (IL-12) plays a critical role in modulating the function of T lymphocytes and natural killer cells. IL-12 has potent antitumor effects in animal models, mediated primarily by its ability to enhance cytolytic activity and secretion of interferon-gamma (IFN-gamma). Unfortunately, the antitumor effect of IL-12 has not been demonstrated in clinical trials. Repeated administration of IL-12 in humans results in decreasing levels of IFN-gamma secretion. To understand the mechanism underlying this loss of responsiveness, the effect of IL-12 on its own signaling in activated human T cells was examined. These experiments demonstrate that the level of the signal transducer and activator of transcription 4 (STAT4) protein, a critical IL-12 signaling component, is dramatically decreased 24 hours after IL-12 stimulation, whereas levels of STAT4 messenger RNA are not affected. The decrease of STAT4 protein appears to be due to specific degradation of phospho-STAT4, possibly through the proteasome degradation pathway. Decreased levels of STAT4 protein lead to decreased STAT4 DNA-binding activity and reduced proliferation and secretion of IFN-gamma. This down-regulation of STAT4 is specific for IL-12 signaling, presumably owing to the prolonged activation of STAT4 induced by IL-12. IFN-alpha stimulation, which leads to transient phosphorylation of STAT4, does not reduce the level of STAT4 protein. These findings provide new insights into the regulation of IL-12 signaling in human T cells, where IL-12 promotes T(H)1 responses, but persistent IL-12 stimulation may also limit this response. The cellular depletion of STAT4 following prolonged IL-12 stimulation may also explain the loss of responsiveness following the repeated administration of IL-12 in clinical trials. (Blood. 2001;97:3860-3866)
Asunto(s)
Proteínas de Unión al ADN/metabolismo , Regulación hacia Abajo , Interleucina-12/farmacología , Transactivadores/metabolismo , Células Cultivadas , Cisteína Endopeptidasas/metabolismo , Proteínas de Unión al ADN/efectos de los fármacos , Proteínas de Unión al ADN/genética , Retroalimentación , Humanos , Interleucina-12/fisiología , Activación de Linfocitos , Complejos Multienzimáticos/metabolismo , Fosforilación , Complejo de la Endopetidasa Proteasomal , ARN Mensajero/efectos de los fármacos , ARN Mensajero/metabolismo , Receptores de Interleucina/efectos de los fármacos , Receptores de Interleucina/metabolismo , Receptores de Interleucina-12 , Factor de Transcripción STAT4 , Transducción de Señal , Linfocitos T/metabolismo , Transactivadores/efectos de los fármacos , Transactivadores/genéticaRESUMEN
BACKGROUND: In patients with chronic myelocytic leukemia (CML), the breakpoint cluster region and fusion between the BCR and the c-ABL genes (BCR-ABL) oncogen product is a potential tumor-specific antigen. Previous studies have shown that T cells specific for the junctional region peptides of the BCR-ABL oncoprotein can be detected in healthy individuals as well as in patients with CML in chronic phase. We assessed whether BCR-ABL- specific T cells could be found in a patient achieving a complete cytogenetic remission after CD4+ donor lymphocyte infusion. METHODS: Using dendritic cells pulsed with BCR-ABL breakpoint peptides as antigen-presenting cells, we stimulated patient peripheral blood lymphocytes to isolate peptide-specific T cell clones present at the time of the cytogenetic response. T cell clones were isolated and the cellular specificity of these cells was examined. RESULTS: A CD3+ CD4+ T cell clone (1F7) that recognizes overlapping p210 junctional peptides presented by HLA-DR molecules was identified and expanded in vitro. Clone 1F7 failed to recognize autologous tumor cells as well as dendritic cells derived from patient CML cells. Clone 1F7 did not inhibit the growth and differentiation of CML precursor cells in a standard colony formation assay. Finally, using a clone-specific probe, 1F7 cells could not be detected in patient peripheral blood at the time of the donor lymphocyte infusion response. CONCLUSIONS: These results suggest that clone 1F7 was selected in vitro using highly potent peptide pulsed dendritic cells but was not representative of the anti-leukemia immune response in vivo. Based on these findings, CD4+ T cells with BCR-ABL specificity do not appear to be mediators of the anti-leukemia response in vivo after donor lymphocyte infusion.
Asunto(s)
Trasplante de Médula Ósea/inmunología , Linfocitos T CD4-Positivos/inmunología , Proteínas de Fusión bcr-abl/inmunología , Leucemia Mielógena Crónica BCR-ABL Positiva/genética , Leucemia Mielógena Crónica BCR-ABL Positiva/inmunología , Transfusión de Linfocitos , Adulto , Secuencia de Aminoácidos , Células Presentadoras de Antígenos/inmunología , Células Clonales , Células Dendríticas/inmunología , Femenino , Antígenos HLA/inmunología , Humanos , Datos de Secuencia Molecular , Fragmentos de Péptidos/inmunologíaRESUMEN
We have studied a case of human primary melanoma displaying the classical signs of a spontaneous regression in order to characterize potentially efficient anti-tumor T cell responses. In a previous series of experiments a unique TCR Vbeta16+ T cell was shown to be highly expanded at the tumor site. The corresponding clone was isolated in vitro and found to be a CD8+ cytotoxic T lymphocyte with a strong and selective cytolytic activity against the autologous tumor cell line. Here, we demonstrate that this predominant Vbeta16+ tumor-infiltrating lymphocyte recognizes a peptide encoded by a novel unconventional myosin class I gene. This peptide includes a mutation due to a single nucleotide substitution. The resulting Glu-->Lys replacement at position 911 of the coding sequence is critical to generate the recognized T cell epitope. These experiments demonstrate the existence of a natural tumor-specific cytolytic T cell response in a primary regressing human melanoma lesion.
Asunto(s)
Antígenos de Neoplasias/inmunología , Citotoxicidad Inmunológica , Melanoma/inmunología , Regresión Neoplásica Espontánea/inmunología , Neoplasias Cutáneas/inmunología , Linfocitos T/inmunología , Anciano , Secuencia de Aminoácidos , Antígenos de Neoplasias/genética , ADN Complementario/genética , Femenino , Humanos , Linfocitos Infiltrantes de Tumor/inmunología , Melanoma/patología , Datos de Secuencia Molecular , Mutación Puntual , Neoplasias Cutáneas/patología , Células Tumorales CultivadasRESUMEN
In recent years, experiments based on the in vitro stimulation of either autologous peripheral blood lymphocytes or tumor-infiltrating lymphocytes with melanoma cells have shown that distinct members of the large MAGE gene family encode tumor-associated antigenic peptides. However, little is still known about natural anti-MAGE responses in vivo. We have studied a case of spontaneously regressing human melanoma, hypothesizing that in this unique situation, the host immune system had developed an efficient cytotoxic T lymphocyte (CTL) response against the cancer cells. Amongst the dense tumor infiltrate, certain clonal populations of T cells were shown to be amplified, thereby suggesting that an antigen-driven selection had occurred at the tumor site. One of the expanded tumor-infiltrating lymphocytes was shown to be a Vbeta13+ CD8+ CTL displaying a strong and selective cytotoxic activity against the autologous melanoma cells. Here we show that this cytotoxic T cell clone recognizes a MAGE-6-encoded peptide. MAGE-6 is therefore the fourth gene of the MAGE family shown to encode antigenic peptide recognized by T cells. Together, these data provide further evidence that T cell responses against MAGE antigens may naturally develop in vivo.
Asunto(s)
Antígenos de Neoplasias/inmunología , Citotoxicidad Inmunológica , Linfocitos Infiltrantes de Tumor/inmunología , Melanoma/inmunología , Regresión Neoplásica Espontánea/inmunología , Neoplasias Cutáneas/inmunología , Anciano , Secuencia de Aminoácidos , Antígenos de Neoplasias/genética , Femenino , Humanos , Datos de Secuencia Molecular , Proteínas de Neoplasias , Linfocitos T Citotóxicos/inmunologíaRESUMEN
With the expansion of newborn screening to include many organic acidurias and fatty acid oxidation defects, effective therapies of these disorders will be needed. Currently severe disorders such as methylmalonic and propionic aciduria. conventional therapy with diet and oral L-camitine often prove ineffective in preventing failure to thrive and recurrent metabolic decompensations. L-carnitine provides a natural pathway for removal of the toxic metabolites in these disorders and is life saving therapy but, with poor oral absorption (25%), it is difficult to supply adequate carnitine to meet the metabolic needs of these patients. Long term intravenous L-carnitine therapy, administered through a subcutaneous venous access port in 5 patients with organic acidurias [propionic aciduria (2), methylmalonic aciduria (2), 3 methylglutaconic aciduria(1)] resulted in improved growth, lower frequency of metabolic decompensations and increased tolerance of natural protein in the diet. An added benefit was the ability to initiate fluid. electrolytes, and antibiotics during metabolic decompensations at home thus averting hospitalizations.
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Carnitina/administración & dosificación , Errores Innatos del Metabolismo/terapia , Catéteres de Permanencia , Femenino , Humanos , Infusiones Intravenosas , Ácido Metilmalónico/orina , Propionatos/orinaRESUMEN
In an earlier study of the immune response in a patient with a cutaneous primary regressive melanoma, a T-cell-receptor diversity analysis demonstrated in situ amplification of certain lymphocytes. Two of them could be cloned and characterized as CD8+ HLA-class-l-restricted CTL with strong selective anti-tumor activity. Following a disease-free period of 3 years, the patient developed a gastric metastasis and subsequently (after an additional year) a metastasis in one axillary lymph node. Melanoma cell lines derived from the 2 secondary lesions have been established here. It was found that these metastatic cells have maintained expression of both HLA-class-I molecules and the peptidic antigen(s) recognized by the 2 clones amplified at the primary site. However, the corresponding T lymphocytes were either undetectable or poorly represented both in the gastric and in the axillary lesions. These results suggest that substantial alterations in the quality of T-cell infiltrates occurred during melanoma progression, despite an apparent stability in presentation of tumor-associated antigen(s) which initially triggered a positive rejection response.
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Linfocitos T CD8-positivos/inmunología , Citotoxicidad Inmunológica , Metástasis Linfática/inmunología , Melanoma/inmunología , Neoplasias Cutáneas/inmunología , Neoplasias Gástricas/inmunología , Anciano , Presentación de Antígeno , Antígenos de Neoplasias/inmunología , Femenino , Antígenos de Histocompatibilidad Clase I/inmunología , Humanos , Linfocitos Infiltrantes de Tumor/inmunología , Melanoma/patología , Regresión Neoplásica Espontánea/inmunología , Neoplasias Cutáneas/patología , Neoplasias Gástricas/secundarioRESUMEN
In this paper we used a multiparametric approach to analyze extensively the events occurring during apoptotic cell death of thymocytes, and furthermore, we asked whether alterations in mitochondrial structure and function are occurring in early stages of apoptosis. A multiparametric quantitative analysis was performed on normal or apoptotic thymocytes emerging from a few-hour culture performed in culture medium or in the presence of dexamethasone. Simultaneous detection of light scattering properties, integrity of plasma membrane (trypan blue exclusion), chromatin condensation (AO/EB staining of entire cells or PI staining of nuclei), and DNA fragmentation (in situ nick-translation in apoptotic cells) allowed a precise analysis of the preapoptotic and apoptotic stages. Moreover a thorough study of mitochondrial transmembrane potential (delta psi m) assessed following in a time course study the uptake by apoptotic cells of the cationic lipophilic dye DiOC6(3) or the J-aggregate-forming cation JC-1, indicates that a drop in delta psi m occurs very early in thymocyte apoptosis, before DNA fragmentation. This is associated with alteration in mitochondrial structure assessed by cytofluorimetric study of NAO uptake in apoptotic cells. Finally these dramatic alterations in mitochondrial structure and function occurring in early stages of apoptosis were confirmed by confocal and electron microscopy analysis.