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1.
Lupus ; 28(9): 1091-1100, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31291846

RESUMO

BACKGROUND: The study aimed to investigate whether HLA-G antigen is expressed in the kidneys of patients affected by lupus nephritis (LN) and whether its detection in renal biopsies could be adopted as a marker of treatment response and prognosis. METHODS: Thirty renal biopsies from patients with LN were selected and analyzed through immunohistochemistry. Laboratory and clinical data were retrospectively collected at baseline, 6 and 12 months and at the latest clinical appointment. A number of patients (63.3%) were treated with rituximab (RTX) +/- methylprednisolone in the induction phase. The expression of HLA-G in glomeruli, tubules and infiltrating cells was examined and compared between lupus patients who achieved either complete or partial renal response and those who did not respond to treatment. RESULTS: HLA-G staining was observed in the glomeruli of 20 of 30 samples from patients with LN. The expression of the antigen was detected in podocytes, along glomerular capillary walls, on parietal glomerular epithelial cells and within the juxtaglomerular apparatus. Seventy per cent of patients whose glomeruli expressed HLA-G achieved partial or complete response at 6 months and 75% at the latest available follow up compared with 30% and 40%, respectively, of those who did not show any expression. The pattern of staining in tubules and infiltrating cells was highly variable precluding any clinical correlation. CONCLUSION: This study demonstrates that HLA-G is expressed in renal tissue in LN. Our retrospective data suggest that its expression could correlate with response to treatment.


Assuntos
Antígenos HLA-G/imunologia , Nefrite Lúpica/tratamento farmacológico , Metilprednisolona/administração & dosagem , Rituximab/administração & dosagem , Adulto , Anti-Inflamatórios/administração & dosagem , Biópsia , Feminino , Seguimentos , Humanos , Fatores Imunológicos/administração & dosagem , Nefrite Lúpica/imunologia , Masculino , Pessoa de Meia-Idade , Projetos Piloto , Estudos Retrospectivos , Resultado do Tratamento , Adulto Jovem
2.
Clin Exp Immunol ; 181(3): 427-33, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-25982097

RESUMO

The mechanisms underlying the exaggerated inflammatory response in Behçet's syndrome (BS) remain poorly understood. We investigated the response of CD14(+) blood monocytes to interferon (IFN)-γ, focusing on the chemokine CXCL10. Chemokine synthesis and release were analysed at a protein and mRNA level following stimulation with IFN-γ. Findings in BS patients were compared with 25 healthy controls (HC), 15 rheumatoid arthritis (RA) and 15 systemic lupus erythematosus (SLE) disease control patients. BS monocytes produced significantly more CXCL10 protein than HC monocytes from 2 h following IFN-γ stimulation, despite equivalent quantities of mRNA, suggesting more efficient translation. This was significantly more pronounced in BS with high disease activity and in those with ocular and neurological clinical manifestations. The imbalance between CXCL10 protein and mRNA expression was not observed in either RA or SLE patients, and was not seen with other chemokines studied (CXCL9, CXCL11 and CCL2). Furthermore, BS monocytes treated with an alternative stimulant (LPS) did not show abnormal tumour necrosis factor (TNF)-α release. Sucrose density gradients to segregate monocyte CXCL10 mRNA into free RNA or polysome-associated RNA showed equal proportions in BS and HC samples, suggesting that the difference between BS and HC may be due to reduced negative control of CXCL10 translation in BS at a post-initiation level. We conclude that BS monocytes have dysfunctional post-transcriptional regulation of CXCL10 mRNA, resulting in over-expression of CXCL10 protein upon IFN-γ stimulation. As CXCL10 is a chemokine that recruits mononuclear cells, this abnormality may contribute to the exaggerated inflammatory responses that characterizes BS.


Assuntos
Síndrome de Behçet/genética , Quimiocina CXCL10/genética , Regulação da Expressão Gênica/efeitos dos fármacos , Interferon gama/farmacologia , Monócitos/efeitos dos fármacos , Adulto , Idoso , Artrite Reumatoide/sangue , Artrite Reumatoide/genética , Artrite Reumatoide/metabolismo , Síndrome de Behçet/sangue , Síndrome de Behçet/metabolismo , Células Cultivadas , Quimiocina CXCL10/metabolismo , Estudos de Coortes , Feminino , Humanos , Lúpus Eritematoso Sistêmico/sangue , Lúpus Eritematoso Sistêmico/genética , Lúpus Eritematoso Sistêmico/metabolismo , Masculino , Pessoa de Meia-Idade , Monócitos/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/genética , Adulto Jovem
3.
Lupus ; 23(11): 1192-6, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-24928830

RESUMO

Lupus nephritis during pregnancy increases morbidity and mortality for mother and baby. Flares are difficult to treat as many therapeutic options are teratogenic or fetotoxic. Steroids alone may be unable to control disease activity and are associated with higher rates of preterm delivery, sepsis and gestational diabetes. Reports of using tacrolimus to treat lupus nephritis in pregnancy are limited. We describe the pregnancies of nine women in whom tacrolimus was successfully used to treat lupus nephritis flare (six patients) or maintain stable disease (three patients). Introduction or dose escalation of oral steroids was avoided in five of the patients who developed active disease and steroid dose was rapidly reduced in the sixth patient. All women with disease flare attained partial or complete remission after starting tacrolimus. None of the women on maintenance treatment developed active disease. We propose tacrolimus as an effective adjuvant or alternative therapy to steroids for treating lupus nephritis flare or maintaining stable disease during pregnancy.


Assuntos
Imunossupressores/uso terapêutico , Nefrite Lúpica/tratamento farmacológico , Complicações na Gravidez/tratamento farmacológico , Tacrolimo/uso terapêutico , Feminino , Humanos , Nefrite Lúpica/fisiopatologia , Gravidez , Complicações na Gravidez/fisiopatologia , Resultado do Tratamento
4.
Lupus ; 22(12): 1267-73, 2013 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-24097999

RESUMO

Lupus nephritis needs to be diagnosed promptly and treated specifically with appropriate immunosuppression. However, all patients with lupus nephritis have by definition chronic kidney disease (CKD) as they will have proteinuria with varying degrees of renal impairment. CKD requires careful additional management, not only to reduce the risk of progression to end-stage renal disease but also because it is probably the strongest risk for cardiovascular morbidity and mortality. This review focuses on the evidence underscoring strategies to prevent progression of CKD beyond the "simple" treatment of the lupus nephritis. The strategies include immaculate control of blood pressure, inhibition of the renin-angiotensin system to reduce blood pressure and proteinuria, and the benefits of lifestyle modifications such as tackling smoking, obesity and exercise. We also review the literature on control of dyslipidaemias which, although clearly of cardiovascular benefit, provide less compelling data for offering renoprotection. We touch on the emerging area of the importance of controlling urate levels in protecting against progressive renal impairment. Finally, there is a reminder about the importance of considering the nephrotoxicity of all medications prescribed for patients with lupus nephritis - above all the need to avoid the use of non-steroidal anti-inflammatory drugs. Overall, the theme is that there is much more to the management of patients with lupus nephritis than "just" the nephritis - a multidisciplinary approach involving nephrologists as well as rheumatologists is more likely to provide the appropriate wider care required for all patients with lupus nephritis.


Assuntos
Falência Renal Crônica/prevenção & controle , Nefrite Lúpica/terapia , Insuficiência Renal Crônica/terapia , Anti-Inflamatórios não Esteroides/efeitos adversos , Anti-Inflamatórios não Esteroides/uso terapêutico , Pressão Sanguínea , Progressão da Doença , Dislipidemias/complicações , Dislipidemias/terapia , Humanos , Terapia de Imunossupressão/métodos , Falência Renal Crônica/etiologia , Falência Renal Crônica/fisiopatologia , Estilo de Vida , Nefrite Lúpica/complicações , Nefrite Lúpica/diagnóstico , Proteinúria/etiologia , Insuficiência Renal Crônica/etiologia , Insuficiência Renal Crônica/fisiopatologia , Ácido Úrico/metabolismo
5.
Best Pract Res Clin Obstet Gynaecol ; 27(6): 877-84, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-23962474

RESUMO

Hypertensive disorders of pregnancy are one of the leading causes of peripartum morbidity and mortality globally. Hypertensive disease in pregnancy is associated with a spectrum of severity, ranging from mild pregnancy-induced hypertension to eclampsia. Although most cases of pre-eclampsia may be managed successfully, severe pre-eclampsia is a life-threatening multisystem disease associated with eclampsia, HELLP (haemolysis, elevated liver enzymes, low platelets) syndrome, acute kidney injury, pulmonary oedema, placental abruption and intrauterine foetal death. Management of severe pre-eclampsia includes identification of high-risk patients, optimisation of antenatal care, early intervention and the identification and early management of complications. In the first instance, oral anti-hypertensive agents, including labetalol, nifedipine and methyldopa, should be tried. If oral anti-hypertensive agents have failed to adequately control blood pressure, intravenous anti-hypertensives should be considered. Commonly used intravenous anti-hypertensives include labetalol, hydralazine and glyceryl trinitrate. In addition to anti-hypertensive agents, close attention should be given to regular clinical examination, assessment of fluid balance, neurologic status and monitoring of other vital signs. Magnesium sulphate should be considered early to prevent seizures. Delivery of the baby is the definitive management of severe pre-eclampsia.


Assuntos
Anti-Hipertensivos/uso terapêutico , Cuidados Críticos , Hipertensão Induzida pela Gravidez/diagnóstico , Hipertensão Induzida pela Gravidez/tratamento farmacológico , Administração Intravenosa , Administração Oral , Anti-Hipertensivos/administração & dosagem , Diagnóstico Precoce , Eclampsia/diagnóstico , Eclampsia/tratamento farmacológico , Feminino , Síndrome HELLP/diagnóstico , Síndrome HELLP/tratamento farmacológico , Humanos , Hidralazina/uso terapêutico , Hipertensão Induzida pela Gravidez/epidemiologia , Labetalol/uso terapêutico , Sulfato de Magnésio/uso terapêutico , Metildopa/uso terapêutico , Nifedipino/uso terapêutico , Nitroglicerina/uso terapêutico , Pré-Eclâmpsia/diagnóstico , Pré-Eclâmpsia/tratamento farmacológico , Gravidez , Medição de Risco , Fatores de Risco , Índice de Gravidade de Doença , Resultado do Tratamento , Reino Unido/epidemiologia
6.
Lupus ; 22(4): 390-9, 2013 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-23553782

RESUMO

The aim of this review is to briefly explore how steroids came to be a presumed adjunct to all treatment regimens for lupus nephritis, despite being the main cause of long term damage among patients with lupus and despite increasingly effective alternative agents. I then go on to compare and contrast how differently immunosuppression regimens have developed in the world of solid organ transplantation. Almost from the start of transplantation a clear goal was to develop steroid sparing regimens - and now units such as our own routinely use induction with a biological, a single week of steroids and then monotherapy with tacrolimus. There has been a clear trend of using biologicals as induction agents and less immunosuppression in the long run but with improved outcomes. The drive has not been the same in lupus nephritis despite there being almost no evidence to support the use of steroids and certainly nothing to suggest correct dosage and timing. Rituximab, a B cell depleting antibody, offers great promise as a treatment agent despite the negative randomised control LUNAR trial. I briefly review our own data, demonstrating that early use of rituximab in lupus nephritis allows omission of oral steroids with excellent rates of remission (complete and partial). I review why the LUNAR trial should not discourage the use of rituximab. Finally, I introduce the RITUXILUP trial, a multicentre randomised controlled trial we are developing to formally evaluate our oral steroid avoiding regimen against a standard treatment regimen of mycophenolate mofetil and steroids. We have to follow the lead of our transplant colleagues and challenge the assumption that the future for lupus nephritis cannot be steroid free.


Assuntos
Linfócitos B/imunologia , Glucocorticoides/uso terapêutico , Nefrite Lúpica/tratamento farmacológico , Anticorpos Monoclonais Murinos/farmacologia , Anticorpos Monoclonais Murinos/uso terapêutico , Desenho de Fármacos , Glucocorticoides/administração & dosagem , Glucocorticoides/efeitos adversos , Humanos , Fatores Imunológicos/farmacologia , Fatores Imunológicos/uso terapêutico , Imunossupressores/farmacologia , Imunossupressores/uso terapêutico , Nefrite Lúpica/imunologia , Transplante de Órgãos/métodos , Ensaios Clínicos Controlados Aleatórios como Assunto , Rituximab
7.
Lupus ; 18(3): 257-63, 2009 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-19213865

RESUMO

Systemic lupus erythematosus (SLE) is a complex, multisystem autoimmune disorder, which often involves referral to multiple medical specialists. Lupus nephritis (LN) occurs in ~35% of adults with SLE and predicts poor survival. There is currently no consensus on how to manage patients with SLE or LN across specialties and across different European countries. The Lupus Nephritis Terminology Advisory Group was formed to address this issue as it impacts upon LN treatment. It has developed consensus statements based on opinions from expert panel meetings with nephrologists, nephropathologists, rheumatologists, clinical immunologists and internal medicine specialists from many European countries, after reviewing current guidelines from the European League Against Rheumatism, the American College of Rheumatology and the participants' experience. In this article, we report consensus statements that were developed in six important areas: classification of patients with LN, how classification affects the selection of treatment options and definitions of induction, response, flare and maintenance. We have also proposed a consensus for the terminology involved in the management of LN that is consistent with clinical opinion gathered from multidisciplinary expert meetings and with existing guidelines. We believe this consensus approach provides agreed expert opinion to clinicians and will form the basis for optimising LN treatment.


Assuntos
Nefrite Lúpica , Projetos de Pesquisa/normas , Terminologia como Assunto , Adulto , Europa (Continente) , Humanos , Nefrite Lúpica/classificação , Nefrite Lúpica/fisiopatologia , Nefrite Lúpica/terapia , Guias de Prática Clínica como Assunto , Índice de Gravidade de Doença , Sociedades Médicas
8.
Clin Exp Immunol ; 153(1): 44-55, 2008 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-18505436

RESUMO

CD4(+) CD25(+) regulatory T cells have been shown to be a vital component of the mechanisms that prevent autoreactivity in mice and also in humans. Previous studies have examined CD4(+) CD25(hi) regulatory T cell frequency and function in patients with systemic lupus erythematosus (SLE) with mixed results. We investigated frequency, phenotype and function in 21 patients with SLE and six with inactive disease. We found no reduction in frequency of the CD25(hi) subset, although active disease was associated with an increased proportion of CD4(+) CD25(+) T cells. When examining function, in the majority of individuals suppression was comparable with controls, although cells isolated from one patient with active disease failed to suppress proliferation. On testing the effect of CD25(hi) depletion on the responses of whole peripheral blood mononuclear cells to nucleosomes we found that, where a response was detectable from patients, depletion augmented interferon-gamma secretion, demonstrating intact suppression of responses implicated in the pathogenesis of SLE. Our results did not confirm an association of failure in CD4(+) CD25(hi) regulatory T cell function or a reduction in their frequency with active disease. Instead, perturbations in the CD4(+) CD25(hi) regulatory T cell population may play a role in disease in only a minority of the patients afflicted by the diverse syndromes of SLE.


Assuntos
Nefrite Lúpica/imunologia , Linfócitos T Reguladores/imunologia , Adolescente , Adulto , Análise de Variância , Estudos de Casos e Controles , Criança , Pré-Escolar , Feminino , Citometria de Fluxo , Humanos , Subunidade alfa de Receptor de Interleucina-2/imunologia , Contagem de Linfócitos , Masculino , Pessoa de Meia-Idade , Nucleossomos/imunologia , Estatísticas não Paramétricas
9.
Rheumatology (Oxford) ; 45(12): 1497-504, 2006 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-17046860

RESUMO

OBJECTIVES: Key aims of the treatment of lupus nephritis (LN) are to induce and maintain remission with minimal side effects. However, assessing ongoing renal inflammatory activity is poorly served by current diagnostic tests apart from renal biopsy, but frequent biopsies cannot be justified. Our long-term aim is to identify novel biomarkers from urinary protein profiles to improve diagnosis and monitoring of activity and response to therapy in LN. METHODS: We used surface enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF MS) to identify biomarkers able to discriminate between urine samples from patients with inactive (n= 49) and active (n= 26) LN. Discriminant function analysis was used to define the minimum number of proteins whose levels best distinguished between the two patient groups. Serial urines of six biopsied patients were studied prospectively, and multiple regression (MR) scores calculated. RESULTS: Proteins with masses of 3340 and 3980 distinguished active from inactive LN with 92% sensitivity and specificity of 92% each. The prospective study of the biopsied patients demonstrated that MR scores could predict both relapse and remission earlier than traditional clinical markers. CONCLUSIONS: SELDI-TOF MS identified potential biomarker profiles strongly associated with activity in LN. Identification of these proteins will allow us to devise specific assays to routinely monitor disease progression, and alter immunosuppressive drug regimens accordingly. These proteins may also play a critical role in the pathogenesis of glomerulonephritis, and could therefore provide targets for therapeutic intervention.


Assuntos
Nefrite Lúpica/diagnóstico , Proteinúria/urina , Adulto , Biomarcadores/urina , Creatinina/sangue , Creatinina/urina , Métodos Epidemiológicos , Feminino , Humanos , Lúpus Eritematoso Sistêmico/urina , Nefrite Lúpica/complicações , Masculino , Pessoa de Meia-Idade , Análise Serial de Proteínas/métodos , Proteinúria/etiologia , Proteômica , Recidiva , Sensibilidade e Especificidade , Índice de Gravidade de Doença , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz
12.
Clin Med (Lond) ; 1(4): 266-73, 2001.
Artigo em Inglês | MEDLINE | ID: mdl-11525571
14.
J Neurosci Nurs ; 33(6): 292-5, 2001 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-11776710

RESUMO

This study examined reasons why patients discontinue the ketogenic diet. A total of 46 children placed on the ketogenic diet between November 1994 and August 1996 were followed prospectively. Reasons for discontinuing the diet prior to 6 months were analyzed. Nineteen (41%) children discontinued the diet for either medical or nonmedical reasons. Nonmedical reasons were caregiver issues and patients' unwillingness to follow the diet. Noncompliance was more common in older children. The ketogenic diet, while effective, is a very stringent diet. Nonmedical reasons for discontinuation are as common as the traditional medical reasons of lack of efficacy or complications.


Assuntos
Gorduras na Dieta/uso terapêutico , Epilepsia/dietoterapia , Cetonas/metabolismo , Cooperação do Paciente , Adolescente , Fatores Etários , Cuidadores , Criança , Pré-Escolar , Feminino , Humanos , Lactente , Cetose/metabolismo , Masculino , Satisfação do Paciente , Estudos Prospectivos , Paladar , Resultado do Tratamento
16.
Am J Kidney Dis ; 33(1): 133-7, 1999 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-9915279

RESUMO

Immune thrombocytopenic purpura (ITP) mediated by quinine-dependent platelet reactive antibodies is well recognized. More recently there have been a number of reports of quinine-induced hemolytic-uremic syndrome (HUS). We describe a patient with quinine-induced immune thrombocytopenia who subsequently developed HUS after re-exposure to a single dose of this drug. To our knowledge, this is the first such case reported. Multiple quinine-dependent antibodies have been characterized in the patient's serum. Initially, quinine-dependent antibodies were directed solely against the platelet glycoprotein complex GPIb/IX. After rechallenge with quinine, there was broadening of quinine-dependent antibody specificities, which were now also directed against the platelet glycoprotein complexes GPIb/IX and GPIIb/IIIa, endothelial cells, and leukocytes. We have shown quinine-dependent antibody-mediated endothelial cell activation, which supports an immunopathogenic role for quinine-dependent antibodies in the causation of this disease.


Assuntos
Síndrome Hemolítico-Urêmica/induzido quimicamente , Relaxantes Musculares Centrais/efeitos adversos , Púrpura Trombocitopênica Idiopática/induzido quimicamente , Quinina/efeitos adversos , Anticorpos/sangue , Síndrome Hemolítico-Urêmica/diagnóstico , Humanos , Perna (Membro) , Masculino , Pessoa de Meia-Idade , Cãibra Muscular/complicações , Cãibra Muscular/tratamento farmacológico , Relaxantes Musculares Centrais/imunologia , Púrpura Trombocitopênica Idiopática/diagnóstico , Quinina/imunologia , Recidiva
17.
J Neurosci Nurs ; 30(2): 124-8, 1998 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-9642620

RESUMO

We integrated the care of patients of all ages (ranging thus far from 4 weeks to 73 years) in our dedicated 8-bed Epilepsy Unit. Administrative issues pertaining to admission and discharge criteria, unit policies and procedures and an interdisciplinary quality assurance plan were examined in relation to the impact of combining both pediatric and adult patients. Clinical considerations included the diversified abilities needed to care for pediatric and adult patients both in relation to the technical skills as well as psychosocial skills required. The advantages of integrating patients of all ages on one unit include having a staff highly trained in assessment and intervention skills for a particular disorder. The psychosocial issues that arise in these patients, regardless of age, tend to encompass the entire family; therefore a holistic approach is appropriate for both children and adults. An autonomous nursing practice was established with the development of critical pathways and patient care protocols. Our experience suggests that integrated specialized units can enhance the care of patients with intractable seizures.


Assuntos
Epilepsia/enfermagem , Unidades Hospitalares , Adolescente , Adulto , Idoso , Criança , Pré-Escolar , Procedimentos Clínicos , Feminino , Humanos , Lactente , Recém-Nascido , Masculino , Pessoa de Meia-Idade , Avaliação em Enfermagem , Admissão do Paciente , Equipe de Assistência ao Paciente , Alta do Paciente , Garantia da Qualidade dos Cuidados de Saúde
18.
Proc Natl Acad Sci U S A ; 94(11): 5772-7, 1997 May 27.
Artigo em Inglês | MEDLINE | ID: mdl-9159149

RESUMO

The independent influences of invariant chain (Ii) and HLA-DM molecules on the array of naturally processed peptides displayed by HLA-DR molecules were studied using transfected cell lines. The absence of Ii led to an altered set of HLA-DR-bound peptides as judged by the discriminating responses of alloreactive T cell clones. While most T cell clones raised against DR+Ii+DM+ peripheral blood mononuclear cells (PBMC) failed to respond to DR+Ii-DM- cells, T cell clones raised against DR+Ii-DM- transfectants were not stimulated by DR+Ii+DM+ cells. Furthermore, coexpression of HLA-DM with HLA-DR1 in the absence of Ii augmented responses of anti-PBMC T cell clones but inhibited allorecognition by T cell clones raised against DR+Ii-DM- transfectants. The conformational integrity of the class II molecules, as judged by serology, suggests that the patterns of reactivity of the T cell clones reflect specificity for different alloantigen-bound peptides. Hence, discordant regulation of expression of major histocompatibility complex class II, Ii, and HLA-DM molecules in vivo may lead to the display of novel self-peptides and possible interruption of self-tolerance.


Assuntos
Antígenos de Diferenciação de Linfócitos B/biossíntese , Antígenos HLA-D/biossíntese , Antígenos HLA-DR/biossíntese , Antígenos HLA-DR/química , Antígenos de Histocompatibilidade Classe II/biossíntese , Células Apresentadoras de Antígenos/imunologia , Antígenos CD/biossíntese , Linhagem Celular , Epitopos/análise , Antígenos HLA-D/imunologia , Humanos , Cinética , Conformação Proteica , Proteínas Recombinantes/biossíntese , Proteínas Recombinantes/química , Linfócitos T/imunologia , Transfecção
20.
J Immunol ; 156(8): 2769-75, 1996 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-8609395

RESUMO

Conflicting results of the effects of Ag presentation by MHC class II-expressing T cells have been described. In some studies class II-expressing T cells have been shown to act as effective APCs, while others have reported that the recognition of Ag on the surface of another T cell inactivates IL-2 production. In this study we have investigated the mechanisms involved in Ag presentation by T cells. The results obtained suggest that 1) lack of costimulation is not responsible for the inhibitory effects of T cell Ag presentation on IL-2 production; the provision of costimulation by immobilized anti-CD28 Ab or by the addition of accessory cells failed to reverse the effects of T cell Ag presentation, but restored the response to immobilized anti-CD3; 2) T cell Ag presentation induced a minimal increase in intracellular Ca2+ compared with that induced by antigen-pulsed B cells; this difference in the calcium response is not explained by quantitative differences in ligand density between B cells and T cells; and 3) despite the weak calcium signal, T cell presentation supported IL-4 release in the absence of IL-2 production. Taken together these data suggest that T cell Ag presentation leads to altered TCR/CD3-transduced signals, which biases the T cell towards a Th2 phenotype.


Assuntos
Apresentação de Antígeno , Células Apresentadoras de Antígenos/imunologia , Interleucina-2/antagonistas & inibidores , Interleucina-2/biossíntese , Interleucina-4/metabolismo , Transdução de Sinais/imunologia , Linfócitos T/imunologia , Animais , Apresentação de Antígeno/efeitos dos fármacos , Células Apresentadoras de Antígenos/efeitos dos fármacos , Células Apresentadoras de Antígenos/metabolismo , Linfócitos B/imunologia , Linfócitos B/metabolismo , Cálcio/metabolismo , Linhagem Celular , Espaço Extracelular/metabolismo , Humanos , Interleucina-12/farmacologia , Interleucina-2/metabolismo , Ativação Linfocitária , Camundongos , Linfócitos T/efeitos dos fármacos , Linfócitos T/metabolismo
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