Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 28
Filtrar
Filtros adicionais











País/Região como assunto
Intervalo de ano
1.
Nat Commun ; 10(1): 3106, 2019 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-31308374

RESUMO

Immune responses need to be controlled tightly to prevent autoimmune diseases, yet underlying molecular mechanisms remain partially understood. Here, we identify biallelic mutations in three patients from two unrelated families in differentially expressed in FDCP6 homolog (DEF6) as the molecular cause of an inborn error of immunity with systemic autoimmunity. Patient T cells exhibit impaired regulation of CTLA-4 surface trafficking associated with reduced functional CTLA-4 availability, which is replicated in DEF6-knockout Jurkat cells. Mechanistically, we identify the small GTPase RAB11 as an interactor of the guanine nucleotide exchange factor DEF6, and find disrupted binding of mutant DEF6 to RAB11 as well as reduced RAB11+CTLA-4+ vesicles in DEF6-mutated cells. One of the patients has been treated with CTLA-4-Ig and achieved sustained remission. Collectively, we uncover DEF6 as player in immune homeostasis ensuring availability of the checkpoint protein CTLA-4 at T-cell surface, identifying a potential target for autoimmune and/or cancer therapy.

2.
Cancer ; 125(11): 1848-1854, 2019 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-30758854

RESUMO

BACKGROUND: Experimental models have demonstrated that immune surveillance by cytotoxic lymphocytes can protect from spontaneous neoplasms and cancer. In humans, defective lymphocyte cytotoxicity is associated with the development of hemophagocytic lymphohistiocytosis, a hyperinflammatory syndrome. However, to the best of the authors' knowledge, the degree to which human lymphocyte cytotoxicity protects from cancer remains unclear. In the current study, the authors examined the risk of lymphoma attributable to haploinsufficiency in a gene required for lymphocyte cytotoxicity. METHODS: The authors exploited a founder effect of an UNC13D inversion, which abolishes Munc13-4 expression and causes hemophagocytic lymphohistiocytosis in an autosomal recessive manner. Within 2 epidemiological screening programs in northern Sweden, an area demonstrating a founder effect of this specific UNC13D mutation, all individuals with a diagnosis of lymphoma (487 patients) and matched controls (1844 controls) were assessed using polymerase chain reaction for carrier status. RESULTS: Among 487 individuals with lymphoma, 15 (3.1%) were heterozygous carriers of the UNC13D inversion, compared with 18 controls (1.0%) (odds ratio, 3.0; P = .002). It is interesting to note that a higher risk of lymphoma was attributed to female carriers (odds ratio, 3.7; P = .004). CONCLUSIONS: Establishing a high regional prevalence of the UNC13D inversion, the authors have reported an overrepresentation of this mutation in individuals with lymphoma. Therefore, the results of the current study indicate that haploinsufficiency of a gene required for lymphocyte cytotoxicity can predispose patients to lymphoma, suggesting the importance of cytotoxic lymphocyte-mediated surveillance of cancer. Furthermore, the results of the current study suggest that female carriers are more susceptible to lymphoma.

5.
Front Immunol ; 8: 426, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28458669

RESUMO

Chediak-Higashi syndrome (CHS) is caused by autosomal recessive mutations in LYST, resulting in enlarged lysosomal compartments in multiple cell types. CHS patients display oculocutaneous albinism and may develop life-threatening hemophagocytic lymphohistiocytosis (HLH). While NK cell-mediated cytotoxicity has been reported to be uniformly defective, variable defects in T cell-mediated cytotoxicity has been observed. The latter has been linked to the degree of HLH susceptibility. Since the discrepancies in NK cell- and T cell-mediated cellular cytotoxicity might result from differences in regulation of cytotoxic granule release, we here evaluated perforin-containing secretory lysosome size and number in freshly isolated lymphocytes from CHS patients and furthermore compared their exocytic capacities. Whereas NK cells from CHS patients generally contained a single, gigantic perforin-containing granule, cytotoxic T cells predominantly contained several smaller granules. Nonetheless, in a cohort of 21 CHS patients, cytotoxic T cell and NK cell granule exocytosis were similarly impaired upon activating receptor stimulation. Mechanistically, polarization of cytotoxic granules was defective in cytotoxic lymphocytes from CHS patients, with EEA1, a marker of early endosomes, mislocalizing to lysosomal structures. The results leads to the conclusion that lysosome enlargement corresponds to loss of distinct organelle identity in the endocytic pathway, which on a subcellular level more adversely affects NK cells than T cells. Hence, vesicular size or numbers do not per se dictate the impairment of lysosomal exocytosis in the two cell types studied.

6.
J Clin Immunol ; 36(5): 480-9, 2016 07.
Artigo em Inglês | MEDLINE | ID: mdl-27146671

RESUMO

PURPOSE: Autosomal recessive mutations in LRBA, encoding for LPS-responsive beige-like anchor protein, were described in patients with a common variable immunodeficiency (CVID)-like disease characterized by hypogammaglobulinemia, autoimmune cytopenias, and enteropathy. Here, we detail the clinical, immunological, and genetic features of a patient with severe autoimmune manifestations. METHODS: Whole exome sequencing was performed to establish a molecular diagnosis. Evaluation of lymphocyte subsets was performed for immunological characterization. Medical files were reviewed to collect clinical and immunological data. RESULTS: A 7-year-old boy, born to consanguineous parents, presented with autoimmune hemolytic anemia, hepatosplenomegaly, autoimmune thyroiditis, and severe autoimmune gastrointestinal manifestations. Immunological investigations revealed low immunoglobulin levels and low numbers of B and NK cells. Treatment included immunoglobulin replacement and immunosuppressive therapy. Seven years after disease onset, the patient developed severe neurological symptoms resembling acute disseminated encephalomyelitis, prompting allogeneic hematopoietic stem cell transplantation (HSCT) with the HLA-identical mother as donor. Whole exome sequencing of the patient uncovered a homozygous 1 bp deletion in LRBA (c.7162delA:p.T2388Pfs*7). Importantly, during 2 years of follow-up post-HSCT, marked clinical improvement and recovery of immune function was observed. CONCLUSIONS: Our data suggest a beneficial effect of HSCT in patients with LRBA deficiency.


Assuntos
Proteínas Adaptadoras de Transdução de Sinal/genética , Anemia Hemolítica Autoimune/terapia , Linfócitos B/imunologia , Imunodeficiência de Variável Comum/terapia , Transplante de Células-Tronco Hematopoéticas , Células Matadoras Naturais/imunologia , Deleção de Sequência/genética , Anemia Hemolítica Autoimune/diagnóstico , Anemia Hemolítica Autoimune/genética , Autoimunidade , Criança , Imunodeficiência de Variável Comum/diagnóstico , Imunodeficiência de Variável Comum/genética , Consanguinidade , Análise Mutacional de DNA , Antígenos HLA/imunologia , Histocompatibilidade , Humanos , Imunoglobulinas/sangue , Masculino , Resultado do Tratamento
8.
Genome Med ; 7: 130, 2015 Dec 18.
Artigo em Inglês | MEDLINE | ID: mdl-26684649

RESUMO

BACKGROUND: Hemophagocytic lymphohistiocytosis (HLH) is a rapid-onset, potentially fatal hyperinflammatory syndrome. A prompt molecular diagnosis is crucial for appropriate clinical management. Here, we validated and prospectively evaluated a targeted high-throughput sequencing approach for HLH diagnostics. METHODS: A high-throughput sequencing strategy of 12 genes linked to HLH was validated in 13 patients with previously identified HLH-associated mutations and prospectively evaluated in 58 HLH patients. Moreover, 2504 healthy individuals from the 1000 Genomes project were analyzed in silico for variants in the same genes. RESULTS: Analyses revealed a mutation detection sensitivity of 97.3%, an average coverage per gene of 98.0%, and adequate coverage over 98.6% of sites previously reported as mutated in these genes. In the prospective cohort, we achieved a diagnosis in 22 out of 58 patients (38%). Genetically undiagnosed HLH patients had a later age at onset and manifested higher frequencies of known secondary HLH triggers. Rare, putatively pathogenic monoallelic variants were identified in nine patients. However, such monoallelic variants were not enriched compared with healthy individuals. CONCLUSIONS: We have established a comprehensive high-throughput platform for genetic screening of patients with HLH. Almost all cases with reduced natural killer cell function received a diagnosis, but the majority of the prospective cases remain genetically unexplained, highlighting genetic heterogeneity and environmental impact within HLH. Moreover, in silico analyses of the genetic variation affecting HLH-related genes in the general population suggest caution with respect to interpreting causality between monoallelic mutations and HLH. A complete understanding of the genetic susceptibility to HLH thus requires further in-depth investigations, including genome sequencing and detailed immunological characterization.


Assuntos
Sequência de Bases , Linfo-Histiocitose Hemofagocítica/diagnóstico , Linfo-Histiocitose Hemofagocítica/genética , Adolescente , Adulto , Idade de Início , Idoso , Criança , Pré-Escolar , Estudos de Coortes , Feminino , Predisposição Genética para Doença , Testes Genéticos , Humanos , Lactente , Recém-Nascido , Masculino , Pessoa de Meia-Idade , Mutação , Estudos Prospectivos , Análise de Sequência de DNA , Adulto Jovem
9.
Lancet Haematol ; 2(12): e536-42, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26686408

RESUMO

BACKGROUND: Mutations in genes for perforin-dependent lymphocyte cytotoxicity are associated with haemophagocytic lymphohistiocytosis, a rare disease of severe hyperinflammation that typically becomes evident in early childhood. It has been suggested that individuals with hypomorphic biallelic mutations in genes associated with haemophagocytic lymphohistiocytosis are at increased risk of developing haematological malignancies. We aimed to assess whether relatives of patients with primary haemophagocytic lymphohistiocytosis (ie, heterozygous carriers of these mutated genes) were more likely to develop cancer. METHODS: In this retrospective cohort study, we used a multigeneration registry to identify relatives (parents and grandparents) of 79 Swedish children (<15 years) with primary haemophagocytic lymphohistiocytosis diagnosed between 1971 and 2011. For each relative, we randomly selected eight matched individuals from the Swedish total population registry, stratified for sex, birth year, and birth region. Relatives and matched controls were cross-linked with the Swedish Cancer Registry to establish cancer incidence rate. We then calculated the incidence rate ratio between first-degree and second-degree relatives and the matched controls. Additionally, we assessed natural-killer-cell-mediated cytotoxicity in a subgroup of first-degree relatives using standard 4 h (51)Cr assay and flow cytometry quantification of the upregulation of surface CD107a. FINDINGS: We identified 346 first-degree and second-degree relatives from 67 families (67 mothers, 66 fathers, 106 grandmothers, and 107 grandfathers) and 2768 matched controls. Median follow-up was 49 years, range 0-54 years. By death or last follow-up (Dec 31, 2012), first-degree relatives had a significantly increased incidence rate of malignancies than did controls (incidence rate per 1000 person-years 2.78 [95% CI 1.42-4.15] vs 1.56 [1.16-1.95]; incidence rate ratio 1.79 [95% CI 1.06-3.03]; p=0.030). Mothers had a particularly increased risk (incidence rate per 1000 person-years 4.43 [95% CI 1.99-6.87] vs 1.60 [1.08-2.11]; incidence rate ratio 2.78 [95% CI 1.48-5.21]; p=0.0014), whereas no difference was found between fathers and controls (1.24 [0.00-2.51] vs 1.52 [0.89-2.15]; 0.82 [0.29-2.29]; p=0.70) or between grandparents and controls (7.24 [5.44-9.04] vs 6.36 [5.70-7.03]; 1.14 [0.88-1.48]; p=0.33). Functional analysis of heterozygous carriers of mutations associated with haemophagocytic lymphohistiocytosis could not show significantly reduced lymphocyte cytotoxicity. INTERPRETATION: Heterozygous mutations in genes associated with haemophagocytic lymphohistiocytosis might be a new risk factor for cancer. The increased risk of cancer might imply haploinsufficiency of cytotoxic lymphocyte-mediated immunosurveillance of cancer in carriers of these mutations. Our findings might support intensified screening for malignancies in relatives of patients with haemophagocytic lymphohistiocytosis. FUNDING: Swedish Children's Cancer Foundation, Swedish Research Council, Histiocytosis Association, Swedish Cancer Society, Swedish Cancer and Allergy Foundation, Mary Béve Foundation, Karolinska Institutet Research Foundation, Stockholm County Council (ALF-project).


Assuntos
Linfo-Histiocitose Hemofagocítica/epidemiologia , Neoplasias/epidemiologia , Adolescente , Adulto , Idoso , Estudos de Casos e Controles , Criança , Estudos de Coortes , Saúde da Família , Feminino , Humanos , Incidência , Linfo-Histiocitose Hemofagocítica/genética , Masculino , Pessoa de Meia-Idade , Sistema de Registros , Estudos Retrospectivos , Fatores de Risco , Suécia/epidemiologia , Adulto Jovem
10.
Pediatr Blood Cancer ; 62(12): 2094-100, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26184781

RESUMO

BACKGROUND: Perforin, encoded by PRF1, is a pore-forming protein crucial for lymphocyte cytotoxicity. Biallelic PRF1 nonsense mutations invariably result in early-onset hemophagocytic lymphohistiocytosis (HLH), termed familial HLH type 2 (FHL2). In contrast, biallelic PRF1 missense mutations may give rise to later-onset disease and more variable manifestations. PROCEDURE: We retrospectively searched our database for patients from families with siblings carrying biallelic PRF1 missense mutations where at least one sibling did not develop HLH, and for patients with biallelic PRF1 missense mutations and an atypical presentation of disease. We reviewed their clinical, genetic, and immunological characteristics. RESULTS: In all, we identified 10 such patients, including three sibling pairs with discordant manifestations. Interestingly, in two families, siblings of late-onset HLH patients developed Hodgkin lymphoma but no HLH. In a third family, one sibling presented with recurrent HLH episodes, whereas the other remains healthy. Of note, the affected sibling also suffered from systemic lupus erythematosus. Additional unrelated patients with biallelic PRF1 missense mutations were affected by neurological disease without classical signs of HLH, gastrointestinal inflammation as initial presentation of disease, as well as a hematological malignancy. Compared to early-onset FHL2 patients, the patients with an atypical presentation displayed a partial recovery of NK cell cytotoxicity upon IL-2 stimulation in vitro. CONCLUSIONS: Our findings substantiate and expand the spectrum of clinical presentations of perforin deficiency, linking PRF1 missense mutations to lymphoma susceptibility and highlighting clinical variability within families. PRF1 mutations should, therefore, be considered as a cause of several diseases disparate to HLH.


Assuntos
Doença de Hodgkin/genética , Lúpus Eritematoso Sistêmico/genética , Linfo-Histiocitose Hemofagocítica/genética , Mutação de Sentido Incorreto , Doenças do Sistema Nervoso/genética , Perforina/genética , Adolescente , Adulto , Feminino , Humanos , Masculino , Estudos Retrospectivos
11.
Pediatr Blood Cancer ; 62(2): 346-352, 2015 02.
Artigo em Inglês | MEDLINE | ID: mdl-25382070

RESUMO

BACKGROUND: Primary hemophagocytic lymphohistiocytosis (HLH) represents a group of inherited hyperinflammatory immunodeficiencies, including familial HLH (FHL), Griscelli syndrome type 2 (GS2), and X-linked lymphoproliferative syndrome (XLP). We previously reported an annual incidence of suspected primary HLH in Sweden 1971-1986 of 0.12 per 100,000 children. Here, we determined if the incidence had increased with concomitant awareness. PROCEDURE: Children <15 years old presenting with HLH 1987-2006 in Sweden were identified through the national mortality registry as well as by nation-wide inquiries to all pediatric centers. HLH was diagnosed according to the HLH-2004 diagnostic guidelines (in case of missing data of at least three of the eight diagnostic criteria, fulfillment of four was sufficient for inclusion). We defined primary HLH as patients presenting with HLH requiring transplantation or dying of disease. RESULTS: Remarkably, the minimal annual incidence rate of primary HLH remained 0.12 per 100,000 children, equating to 1.8 per 100,000 live births. Notably, an increased overall survival was observed in 1997-2006, relative to the period 1987-1996. During the subsequent 5-year period, 2007-2011, the incidence of genetically and/or functionally verified primary HLH was 0.15 per 100,000 children per year, suggesting that new assays may aid the identification of patients with primary HLH. CONCLUSION: The annual incidence of primary HLH in Sweden is 0.12-0.15 per 100,000 children per year. Pediatr Blood Cancer 2015;62:346-352. © 2014 Wiley Periodicals, Inc.


Assuntos
Transplante de Células-Tronco Hematopoéticas , Linfo-Histiocitose Hemofagocítica/epidemiologia , Linfo-Histiocitose Hemofagocítica/terapia , Adolescente , Criança , Pré-Escolar , Humanos , Lactente , Linfo-Histiocitose Hemofagocítica/mortalidade , Sistema de Registros , Taxa de Sobrevida , Suécia/epidemiologia
12.
Pediatr Blood Cancer ; 61(12): 2313-5, 2014 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-25110876

RESUMO

Individuals with biallelic truncating PRF1 mutations typically present with fulminant early-onset familial hemophagocytic lymphohistiocytosis (FHL). We report a 19-year-old male with a 5-year history of recurrent fever and headaches progressing to refractory seizures. Brain imaging revealed multiple ring enhancing lesions. Laboratory investigations demonstrated that the patient displayed defective lymphocyte cytotoxicity and carried a homozygous missense PRF1 mutation, c.394G > A (p.Gly132Arg). The patient was successfully treated with chemo-immunotherapy followed by matched related allogeneic hematopoietic stem cell transplantation (HSCT). Our findings demonstrate that prompt HSCT of late-onset FHL with primarily neurological manifestation can reverse central nervous system symptoms and improve long-term outcome.


Assuntos
Anticorpos Monoclonais Murinos/uso terapêutico , Antineoplásicos/uso terapêutico , Encefalopatias/terapia , Transplante de Células-Tronco Hematopoéticas , Linfo-Histiocitose Hemofagocítica/complicações , Mutação/genética , Perforina/genética , Adolescente , Encefalopatias/etiologia , Terapia Combinada , Feminino , Humanos , Masculino , Prognóstico , Rituximab
14.
J Exp Med ; 211(6): 1079-91, 2014 Jun 02.
Artigo em Inglês | MEDLINE | ID: mdl-24842371

RESUMO

Autosomal recessive mutations in UNC13D, the gene that encodes Munc13-4, are associated with familial hemophagocytic lymphohistiocytosis type 3 (FHL3). Munc13-4 expression is obligatory for exocytosis of lytic granules, facilitating cytotoxicity by T cells and natural killer (NK) cells. The mechanisms regulating Munc13-4 expression are unknown. Here, we report that Munc13-4 is highly expressed in differentiated human NK cells and effector CD8(+) T lymphocytes. A UNC13D c.118-308C>T mutation, causative of FHL3, disrupted binding of the ETS family member ELF1 to a conserved intronic sequence. This mutation impairs UNC13D intron 1 recruitment of STAT4 and the chromatin remodeling complex component BRG1, diminishing active histone modifications at the locus. The intronic sequence acted as an overall enhancer of Munc13-4 expression in cytotoxic lymphocytes in addition to representing an alternative promoter encoding a novel Munc13-4 isoform. Mechanistically, T cell receptor engagement facilitated STAT4-dependent Munc13-4 expression in naive CD8(+) T lymphocytes. Collectively, our data demonstrates how chromatin remodeling within an evolutionarily conserved regulatory element in intron 1 of UNC13D regulates the induction of Munc13-4 expression in cytotoxic lymphocytes and suggests that an alternative Munc13-4 isoform is required for lymphocyte cytotoxicity. Thus, mutations associated with primary immunodeficiencies may cause disease by disrupting transcription factor binding.


Assuntos
Linfócitos T CD8-Positivos/imunologia , Síndromes de Imunodeficiência/imunologia , Células Matadoras Naturais/imunologia , Proteínas de Membrana/imunologia , Mutação Puntual/imunologia , Western Blotting , Linfócitos T CD8-Positivos/metabolismo , Células Cultivadas , Citotoxicidade Imunológica/genética , Citotoxicidade Imunológica/imunologia , DNA Helicases/genética , DNA Helicases/imunologia , DNA Helicases/metabolismo , Regulação da Expressão Gênica/imunologia , Humanos , Síndromes de Imunodeficiência/genética , Síndromes de Imunodeficiência/metabolismo , Íntrons/genética , Células Matadoras Naturais/metabolismo , Linfo-Histiocitose Hemofagocítica/genética , Linfo-Histiocitose Hemofagocítica/imunologia , Linfo-Histiocitose Hemofagocítica/metabolismo , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Proteínas Nucleares/genética , Proteínas Nucleares/imunologia , Proteínas Nucleares/metabolismo , Ligação Proteica/genética , Ligação Proteica/imunologia , Isoformas de Proteínas/genética , Isoformas de Proteínas/imunologia , Isoformas de Proteínas/metabolismo , Interferência de RNA , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Fator de Transcrição STAT4/genética , Fator de Transcrição STAT4/imunologia , Fator de Transcrição STAT4/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/imunologia , Fatores de Transcrição/metabolismo
15.
Exp Cell Res ; 325(1): 10-7, 2014 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-24680986

RESUMO

In experimental settings, lymphocyte cytotoxicity has been recognized as a central mechanism for immune defense against infected and neoplastic cells. More recently, molecular determinants of lymphocyte cytotoxicity have been identified through studies of rare, inherited hyperinflammatory and lymphoproliferative syndromes that include hemophagocytic lymphohistiocytosis (HLH). These studies have unraveled a set of genes pivotal for the biogenesis and directed release of perforin-containing lysosomes that mediate target cell killing, in addition to other pathways including Fas that also contribute to induction of cell death. Furthermore, studies of such human primary immunodeficiencies have highlighted non-redundant roles of perforin for maintenance of immune homeostasis. Besides providing mechanistic insights to lymphocyte cytotoxicity, studies of individuals with rare hyperinflammatory diseases are highlighting the relevance of lymphocyte cytotoxicity to more common human diseases. It is increasingly recognized that mutations abrogating lymphocyte cytotoxicity not only cause HLH, but also are associated with susceptibility to cancer and autoimmune syndromes. In addition, patients may initially be present with neurological symptoms or severe infectious disease masquerading as variable immunodeficiency syndrome. Here, we highlight new knowledge regarding the molecular mechanisms regulating lymphocyte cytotoxicity and review how mutations in genes associated with HLH cause disease. We also discuss the wider implications of impairments in lymphocyte cytotoxicity for human disease predisposition.


Assuntos
Citotoxicidade Imunológica , Linfo-Histiocitose Hemofagocítica/imunologia , Animais , Autoimunidade , Degranulação Celular , Predisposição Genética para Doença , Neoplasias Hematológicas/genética , Neoplasias Hematológicas/imunologia , Humanos , Células Matadoras Naturais/imunologia , Linfo-Histiocitose Hemofagocítica/genética , Linfo-Histiocitose Hemofagocítica/fisiopatologia , Linfócitos T Citotóxicos/imunologia
16.
Front Immunol ; 4: 515, 2014 Jan 14.
Artigo em Inglês | MEDLINE | ID: mdl-24459464

RESUMO

Familial hemophagocytic lymphohistiocytosis (FHL) is an often-fatal hyperinflammatory disorder caused by autosomal recessive mutations in PRF1, UNC13D, STX11, and STXBP2. We identified a homozygous STX11 mutation, c.173T > C (p.L58P), in three patients presenting clinically with hemophagocytic lymphohistiocytosis from unrelated Pakistani families. The mutation yields an amino acid substitution in the N-terminal Habc domain of syntaxin-11 and resulted in defective natural killer cell degranulation. Notably, syntaxin-11 expression was decreased in patient cells. However, in an ectopic expression system, syntaxin-11 L58P was expressed at levels comparable to wild-type syntaxin-11, but did not bind Munc18-2. Moreover, another N-terminal syntaxin-11 mutant, R4A, also did not bind Munc18-2. Thus, we have identified a novel missense STX11 mutation causative of FHL type 4. The syntaxin-11 R4A and L58P mutations reveal that both the N-terminus and Habc domain of syntaxin-11 are required for binding to Munc18-2, implying similarity to the dynamic binary binding of neuronal syntaxin-1 to Munc18-1.

18.
Blood ; 121(8): 1345-56, 2013 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-23287865

RESUMO

Cytotoxic lymphocytes, encompassing cytotoxic T lymphocytes (CTLs) and natural killer (NK) cells, kill pathogen-infected, neoplastic, or certain hematopoietic cells through the release of perforin-containing lytic granules. In the present study, we first performed probability-state modeling of differentiation and lytic granule markers on CD8(+) T cells to enable the comparison of bona fide CTLs with NK cells. Analysis identified CD57(bright) expression as a reliable phenotype of granule marker-containing CTLs. We then compared CD3(+)CD8(+)CD57(bright) CTLs with NK cells. Healthy adult peripheral blood CD3(+)CD8(+)CD57(bright) CTLs expressed more granzyme B but less perforin than CD3(-)CD56(dim) NK cells. On stimulation, such CTLs degranulated more readily than other T-cell subsets, but had a propensity to degranulate that was similar to NK cells. Remarkably, the CTLs produced cytokines more rapidly and with greater frequency than NK cells. In patients with biallelic mutations in UNC13D, STX11, or STXBP2 associated with familial hemophagocytic lymphohistiocytosis, CTL and NK cell degranulation were similarly impaired. Therefore, cytotoxic lymphocyte subsets have similar requirements for Munc13-4, syntaxin-11, and Munc18-2 in lytic granule exocytosis. The present results provide a detailed comparison of human CD3(+)CD8(+)CD57(bright) CTLs and NK cells and suggest that analysis of CD57(bright) CTL function may prove useful in the diagnosis of primary immunodeficiencies including familial hemophagocytic lymphohistiocytosis.


Assuntos
Antígenos CD57/metabolismo , Citocinas/metabolismo , Grânulos Citoplasmáticos/metabolismo , Síndromes de Imunodeficiência/metabolismo , Células Matadoras Naturais/metabolismo , Linfócitos T Citotóxicos/metabolismo , Adulto , Biomarcadores/metabolismo , Complexo CD3/metabolismo , Antígenos CD8/metabolismo , Degranulação Celular/imunologia , Citocinas/biossíntese , Grânulos Citoplasmáticos/imunologia , Exocitose/imunologia , Humanos , Síndromes de Imunodeficiência/diagnóstico , Síndromes de Imunodeficiência/imunologia , Imunofenotipagem , Células Matadoras Naturais/citologia , Células Matadoras Naturais/imunologia , Proteínas de Membrana/metabolismo , Proteínas Munc18/metabolismo , Perforina , Proteínas Citotóxicas Formadoras de Poros/metabolismo , Proteínas Qa-SNARE/metabolismo , Subpopulações de Linfócitos T/citologia , Subpopulações de Linfócitos T/imunologia , Subpopulações de Linfócitos T/metabolismo , Linfócitos T Citotóxicos/citologia , Linfócitos T Citotóxicos/imunologia
19.
Haematologica ; 98(5): 760-4, 2013 May.
Artigo em Inglês | MEDLINE | ID: mdl-23100279

RESUMO

Experimental model systems have delineated an important role for cytotoxic lymphocytes in the immunosurveillance of cancer. In humans, perforin-deficiency has been associated with occurrence of hematologic malignancies. Here, we describe an Epstein-Barr virus-positive classical Hodgkin's lymphoma in a patient harboring biallelic mutations in STXBP2, a gene required for exocytosis of perforin-containing lytic granules and associated with familial hemophagocytic lymphohistocytosis. Cytotoxic T lymphocytes were found infiltrating the tumor, and a high frequency of Epstein-Barr virus-specific cytotoxic T lymphocytes were detected in peripheral blood. However, lytic granule exocytosis and cytotoxicity by cytotoxic T lymphocytes, as well as natural killer cells, were severely impaired in the patient. Thus, the data suggest a link between defective lymphocyte exocytosis and development of lymphoma in STXBP2-deficient patients. Therefore, with regards to treatment of familial hemophagocytic lymphohistocytosis patients with mutations in genes required for lymphocyte exocytosis, it is important to consider both the risks of hemophagocytic lymphohistocytosis and malignancy.


Assuntos
Alelos , Transformação Celular Neoplásica/genética , Doença de Hodgkin/genética , Proteínas Munc18/genética , Mutação , Adolescente , Transformação Celular Viral , Feminino , Expressão Gênica , Doença de Hodgkin/diagnóstico , Doença de Hodgkin/virologia , Humanos , Linfócitos do Interstício Tumoral/patologia , Imagem Multimodal , Proteínas Munc18/metabolismo , Linfócitos T Citotóxicos/patologia
20.
Blood ; 118(22): 5783-93, 2011 Nov 24.
Artigo em Inglês | MEDLINE | ID: mdl-21931115

RESUMO

Familial hemophagocytic lymphohistiocytosis (FHL) is an autosomal recessive, often-fatal hyperinflammatory disorder. Mutations in PRF1, UNC13D, STX11, and STXBP2 are causative of FHL2, 3, 4, and 5, respectively. In a majority of suspected FHL patients from Northern Europe, sequencing of exons and splice sites of such genes required for lymphocyte cytotoxicity revealed no or only monoallelic UNC13D mutations. Here, in 21 patients, we describe 2 pathogenic, noncoding aberrations of UNC13D. The first is a point mutation localized in an evolutionarily conserved region of intron 1. This mutation selectively impairs UNC13D transcription in lymphocytes, abolishing Munc13-4 expression. The second is a 253-kb inversion straddling UNC13D, affecting the 3'-end of the transcript and likewise abolishing Munc13-4 expression. Carriership of the intron 1 mutation was found in patients across Europe, whereas carriership of the inversion was limited to Northern Europe. Notably, the latter aberration represents the first description of an autosomal recessive human disease caused by an inversion. These findings implicate an intronic sequence in cell-type specific expression of Munc13-4 and signify variations outside exons and splice sites as a common cause of FHL3. Based on these data, we propose a strategy for targeted sequencing of evolutionary conserved noncoding regions for the diagnosis of primary immunodeficiencies.


Assuntos
Linfo-Histiocitose Hemofagocítica/genética , Proteínas de Membrana/genética , Células Cultivadas , Pré-Escolar , Croácia , Análise Mutacional de DNA , Dinamarca , Feminino , Finlândia , Humanos , Lactente , Recém-Nascido , Íntrons/genética , Linfo-Histiocitose Hemofagocítica/classificação , Masculino , Mutação/fisiologia , Inversão de Sequência/fisiologia , Suécia , Ucrânia
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA