RESUMO
Among other effects, prostaglandins (PG) of the E series are known to inhibit several acute and chronic inflammatory conditions in vivo and proinflammatory cytokine production by activated macrophages in culture. The research presented here demonstrates that the inhibitory effect of PGE2 on tumor necrosis factor alpha (TNF-alpha) and interleukin 6 (IL-6) production by lipopolysaccharide (LPS)-stimulated murine peritoneal macrophages involves IL-10. In a dose-dependent manner, PGE2 inhibits LPS-induced release of TNF-alpha and IL-6, but not of lactate or nitric oxide. The decrease in the level of these cytokines is inversely proportional to the increase in immunoreactive IL-10. This differential inhibitory effect of PGE2 is mimicked by agents that elevate intracellular levels of cAMP, but not cGMP. Neutralizing anti IL-10 antibody but not neutralizing antibodies against other macrophage secretory products (IL-6, leukemia inhibitory factor, and transforming growth factor beta [TGF-beta]), significantly reverse the potent inhibitory effect of PGE2. In vivo, the administration of PGE2 before LPS challenge significantly reduces circulating TNF-alpha and IL-6 levels. Anti-IL-10 antibody substantially enhanced the LPS-induced TNF-alpha and IL-6 levels in mice that received either LPS alone or LPS plus PGE2. These results suggest that the anti-inflammatory effect of PGE2 on mononuclear phagocytes is mediated in part by an autocrine feedback mechanism involving IL-10.
Assuntos
Interleucina-10/fisiologia , Lipopolissacarídeos/farmacologia , Ativação de Macrófagos/efeitos dos fármacos , Macrófagos Peritoneais/imunologia , Prostaglandinas E/farmacologia , 1-Metil-3-Isobutilxantina/farmacologia , Análise de Variância , Animais , Anticorpos Monoclonais/farmacologia , Bioensaio , Bucladesina/farmacologia , Células Cultivadas , Cruzamentos Genéticos , AMP Cíclico/metabolismo , GMP Cíclico/metabolismo , Ensaio de Imunoadsorção Enzimática , Interleucina-10/imunologia , Interleucina-6/biossíntese , Cinética , Lactatos/metabolismo , Macrófagos Peritoneais/efeitos dos fármacos , Macrófagos Peritoneais/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Óxido Nítrico/metabolismo , Choque Séptico/imunologia , Fator de Necrose Tumoral alfa/biossínteseRESUMO
The administration of cAMP-elevating agents affects a number of autoimmune and inflammatory conditions. Because dendritic cells (DCs) play a pivotal role in autoimmunity and inflammation, the isolated effects of cAMP-elevating agents on the function of DCs was examined. In a dose-dependent manner, 8-Bromo cAMP, prostaglandin E(2), and 3-isobutyl-1-methylxanthine inhibited tumor necrosis factor alpha release and suppressed antigen presentation by DCs. The same effect was observed with rolipram, a specific inhibitor of phosphodiesterase type 4, but not with inhibitors of other phosphodiesterases. The decreased antigen presentation by DCs was associated with an enhanced production of interleukin (IL)-10 and with lower major histocompatibility complex type II (MHC II) expression. Furthermore, the inhibition of antigen presentation and MHC II expression was significantly reversed by treatment of DCs with neutralizing antibody against IL-10, suggesting the involvement of an IL-10-dependent mechanism. Taken together, these results might explain why certain cAMP-elevating agents such as rolipram are effective in blocking autoimmunity and inflammation.
Assuntos
Apresentação de Antígeno/efeitos dos fármacos , AMP Cíclico/imunologia , Células Dendríticas/efeitos dos fármacos , Células Dendríticas/imunologia , 1-Metil-3-Isobutilxantina/farmacologia , 8-Bromo Monofosfato de Adenosina Cíclica/farmacologia , Animais , Células Cultivadas , Interleucina-10/imunologia , Camundongos , Camundongos Endogâmicos BALB C , Inibidores de Fosfodiesterase/farmacologia , Rolipram/farmacologia , Fator de Necrose Tumoral alfa/imunologiaRESUMO
An asymptomatic 69-year-old man was admitted to our hospital for an abnormal shadow on the chest X-ray of a medical examination. He had undergone an operation for a hemangioma in the neck (incomplete resection) 39 years before admission. Computed tomography (CT) of the neck and chest revealed an giant cystic mass in the neck extended into the mediastinum, severe deviation of the trachea to the right and fluid collection in the mediastinum. It was considered to be a giant hemangioma with mediastinal hemorrhage by the rupture of the tumor. After the large afferent and efferent vessels were identified by angiography and venography, we performed the resection of the tumor. Pathological examination confirmed the diagnosis of arteriovenous hemangioma.
Assuntos
Neoplasias de Cabeça e Pescoço/patologia , Hemangioma/patologia , Neoplasias do Mediastino/patologia , Idoso , Neoplasias de Cabeça e Pescoço/cirurgia , Hemangioma/cirurgia , Humanos , Imageamento por Ressonância Magnética , Masculino , Neoplasias do Mediastino/diagnóstico por imagem , Invasividade Neoplásica , Reoperação , Ruptura Espontânea , Tomografia Computadorizada por Raios XRESUMO
A 57-year-old man came to our hospital by ambulance for a chest injury by a rifle gunshot. He had a penetrating injury of the chest wall, hemopneumothorax and pulmonary laceration. He was managed with chest drainage, oxygen inhalation. His respiratory and cardiac status was stable. However, for the purpose to prevent the development of empyema or pneumonia, and to check the existence of damage of intrathoracic structures by the gunshot injury, thoracoscopy was performed next day. He discharged without postoperative complications 17 days after the injury. Open thoracotomy is reported to be required in only about 10-15% of patients with chest injuries. However, operative indication of the chest injuries may spread in the future with the spread of thoracoscopy and its low invasiveness.
Assuntos
Lesão Pulmonar , Pulmão/cirurgia , Toracoscopia , Ferimentos por Arma de Fogo/cirurgia , Ferimentos Penetrantes/cirurgia , Hemopneumotórax/etiologia , Hemopneumotórax/cirurgia , Humanos , Masculino , Pessoa de Meia-Idade , Radiografia Torácica , Toracotomia , Ferimentos por Arma de Fogo/diagnóstico por imagem , Ferimentos Penetrantes/diagnóstico por imagemRESUMO
We examined the effect of polymorphonuclear cells on the release of tumor necrosis factor (TNFalpha) in endotoxin-treated macrophages. Human peripheral blood neutrophils were co-cultured with mouse peritoneal macrophages stimulated with lipopolysaccharide (LPS). In a dose-dependent manner, FMLP (n-formyl-methionyl-leucyl-phenylalanine) augmented the release of TNFalpha by LPS-stimulated macrophages in the presence, but not in the absence, of neutrophils. The stimulating effect of neutrophils on macrophages was reversed by catalase, suggesting that the release of hydrogen peroxide from neutrophils was responsible for augmenting macrophage TNFalpha. Moreover, the direct addition of hydrogen peroxide to macrophages resulted in an increased secretion of TNFalpha. In addition, insertion of a porous membrane between the neutrophils and macrophages cancelled the effect, indicating that adherence of neutrophils may be necessary for augmentation of TNFalpha release. In summary, the data suggest that hydrogen peroxide released from stimulated neutrophils may act as an activator of macrophage function by increasing their release of TNFalpha.
Assuntos
Macrófagos Peritoneais/imunologia , Neutrófilos/imunologia , Fator de Necrose Tumoral alfa/metabolismo , Animais , Catalase/farmacologia , Adesão Celular , Técnicas de Cocultura , Humanos , Peróxido de Hidrogênio/metabolismo , Lipopolissacarídeos/farmacologia , Macrófagos Peritoneais/efeitos dos fármacos , Macrófagos Peritoneais/fisiologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , N-Formilmetionina Leucil-Fenilalanina/farmacologia , Neutrófilos/efeitos dos fármacos , Neutrófilos/fisiologiaRESUMO
In several studies, the anabolic hormones insulin-like growth factor-1 (IGF-1) and insulin attenuated several metabolic changes associated with cancer cachexia. In the present study, we evaluated the effect of these hormones on the cachexia associated with colon-26 (C-26) tumor. Healthy age-matched and tumor-bearing mice were treated with two daily doses of IGF-1 (50 micrograms/kg in toto), or insulin (1 U in toto). Determinants of cachexia were body and tumor weight, epididymal fat pad and serum glucose concentrations. Neither IGF-1 nor insulin treatment had a significant effect on the cachectic parameters of C-26-bearing mice. These hormones were biologically active, being capable of inducing weight gain in hypophysectomized mice and hypoglycemia, respectively. Although IGF-1 and insulin have been used to treat cancer-related weight loss, the research presented here suggests that the beneficial effect of these hormones is not universal.
Assuntos
Caquexia/fisiopatologia , Neoplasias do Colo/fisiopatologia , Fator de Crescimento Insulin-Like I/farmacologia , Insulina/farmacologia , Análise de Variância , Animais , Glicemia/metabolismo , Peso Corporal , Caquexia/prevenção & controle , Humanos , Proteínas de Ligação a Fator de Crescimento Semelhante a Insulina/sangue , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos DBA , Proteínas Recombinantes/farmacologiaRESUMO
In congestive heart failure, lymph flow from the cannulated thoracic duct is greatly increased. However, there has been scant data on lymph flow in the intact lymphatic system with systemic circulatory congestion. In the present study, thoracic duct and peripheral lymph flow were qualitatively determined using heated cross-thermocouples in seven mongrel dogs. Central venous pressure was raised artificially by infusing large volumes of crystalloid solution equivalent to a maximum of 30% of body weight. Although both thoracic duct and peripheral lymph flow increased with an intact (closed) lymphatic system, the increase was notably less than with a transected (opened) cervical thoracic duct. With systemic circulatory congestion, cannulated thoracic duct lymph flow circumvents a major lymph impediment to lymph flow (i.e. high central venous pressure) and therefore considerably overestimates in vivo central lymph flow in this condition.
Assuntos
Linfa/fisiologia , Sistema Linfático/fisiologia , Ducto Torácico/fisiologia , Animais , Pressão Sanguínea , Volume Sanguíneo , CãesRESUMO
Ultrasonically guided puncture of the prostate was carried out in 10 patients with prostatic disease. Biopsy of the aiming portion of the prostate was performed with more certainty and safety by this method than the conventional blind procedure. In the 15 cases having the suspicion of seminal vesicle disorder, the seminal vesicle was punctured under ultrasound control. By this procedure, the seminal vesicle fluid was safely and accurately obtained.
Assuntos
Biópsia por Agulha/métodos , Próstata/patologia , Punções , Glândulas Seminais/patologia , Ultrassonografia , Adulto , Idoso , Humanos , Masculino , Pessoa de Meia-Idade , Neoplasias da Próstata/patologia , Punções/métodosRESUMO
We treated two children with 2,8-dihydroxyadenine urolithiasis for over 7 years. The male prepositus was admitted to the hospital because of anuria when he was 10 months old. Bilateral urinary stones had caused the anuria. The stones were 2,8-dihydroxyadenine and his APRT activity was low. He has been treated with about 5.0 mg/kg/day of allopurinol without purine diet restriction. His sister, 3 years old at that time, also was found to have a renal stone. She has been treated with about 3.3 mg/kg/day of allopurinol without restricting purine. The allopurinol therapy without purine-restriction resulted in normal growth of both children with neither the recurrence of stone nor renal impairment.
Assuntos
Adenina/análogos & derivados , Cálculos Urinários/química , Adenina/análise , Adenina Fosforribosiltransferase/deficiência , Adenina Fosforribosiltransferase/genética , Pré-Escolar , Saúde da Família , Feminino , Humanos , Lactente , Masculino , Cálculos Urinários/genéticaRESUMO
The results of clinical use of an extracorporeal shock wave lithotripter (Biolithos MARK III) are presented. From May 1991 through February 1992, a total of 50 sessions were carried out on 33 patients with upper urinary tract stones. Treatments were performed on an outpatient basis, and none of the patients needed anesthesia or analgesia. One month after the last session, 18 patients (54.5%) were free from stone fragments and 6 (18.2%) had stone fragments equal to or smaller than 4 mm. The over-all successful rate obtained by these categories was 72.7%. After treatment no serious complications were observed. Although gross hematuria appeared in almost all patients, pain was noted in only 5 patients. Laboratory data after treatments showed slight and transient changes. It is concluded that Biolithos MARK III is useful and safe in the management of upper urinary tract stones on an outpatient basis.
Assuntos
Litotripsia , Cálculos Urinários/terapia , Adolescente , Adulto , Idoso , Feminino , Humanos , Litotripsia/instrumentação , Masculino , Pessoa de Meia-IdadeRESUMO
Allylestrenol at the daily dose of 50 mg was administered to 45 patients with benign prostatic hypertrophy. The treatment was performed for more than 12 weeks in 40 patients, and improvements, marked and moderate, were observed in 22 patients (55%) in the overall judgement. As side effects of this drug, decrease of potency was observed in 3 cases, decrease of libido in 1 case, pigmentation on breasts in 2 cases, palpitation in 2 cases, short breath in 1 case, and gastrointestinal symptoms in 1 case. However, these side effects were not serious. Our trial suggests that the treatment of benign prostatic hypertrophy with allylestrenol can be useful in urological clinics.
Assuntos
Alilestrenol/uso terapêutico , Estrenos/uso terapêutico , Hiperplasia Prostática/tratamento farmacológico , Idoso , Alilestrenol/farmacologia , Avaliação de Medicamentos , Humanos , Masculino , Pessoa de Meia-Idade , Tamanho do Órgão/efeitos dos fármacos , Próstata/efeitos dos fármacos , Urodinâmica/efeitos dos fármacosRESUMO
Two hundred and twenty patients with prostatic cancer were treated in our clinic during the past ten years between April, 1977 and March, 1987. The age distribution was from 45 to 91 years old and more than half of patients were in seventies. Stages A, B, C and D were 3.5%, 19.7%, 21.2% and 55.6%, respectively. Hormonal therapy was given in 175 cases (79.5%) as an initial treatment. The first therapy showed effectiveness in 181 (83.8%) of 216 cases; in 153 (87.4%) of 175 cases treated by hormonal therapy. Reactivation after the initial treatment was observed in 59 (32.6%) of 181 cases; in 48 (31.4%) of 153 cases treated by hormonal therapy. The interval between the start of treatment and reactivation for the stage D was significantly shorter than that for the other stages. Elevation of serum alkaline-phosphatase levels, accelerated erythrocyte sedimentation rate and hydronephrosis were significant risk factors for reactivation. Of the 220 cases, 51 (23.2%) died of advanced cancer. The overall 5-year survival rate was 41.2%. High grade and high stage were significantly related to the poor prognosis. In our studies, as hormonal therapy, maintenance on 100 mg of diethylstilbestrol diphosphate daily was found effective for the treatment of prostatic cancer.
Assuntos
Adenocarcinoma/terapia , Neoplasias da Próstata/terapia , Adenocarcinoma/mortalidade , Idoso , Idoso de 80 Anos ou mais , Terapia Combinada , Estudos de Avaliação como Assunto , Humanos , Masculino , Pessoa de Meia-Idade , Prognóstico , Neoplasias da Próstata/mortalidade , Taxa de SobrevidaRESUMO
We reported a case of halothane-induced fulminant hepatitis with acute renal failure which developed 6 days after reexposure to halothane. The patient was a 58-year-old female. She had a history of liver dysfunction after exposure to halothane 6 years previously. She had surgical treatment of clubfoot under halothane anesthesia in other hospital. Preoperative physical examination and laboratory data were normal. On the 6th post-operative day she abruptly developed high fever and general fatigue. Next day, she was transferred to our hospital. At admission, fulminant hepatitis complicated with acute renal failure was diagnosed with severe liver and renal damage. She was immediately treated with plasma exchange, glucose-insulin therapy, and hemodialysis. Serum transaminase level returned to normal value within a week. However, despite repeated hemodialysis, renal function did not improve, and she died of P. aeruginosa sepsis on 28th day after the operation. It may be suggested that in this patient hypersensitivity to halothane has persisted during the six years.
Assuntos
Anestesia por Inalação , Doença Hepática Induzida por Substâncias e Drogas/etiologia , Halotano/efeitos adversos , Injúria Renal Aguda/etiologia , Feminino , Humanos , Pessoa de Meia-IdadeRESUMO
The crystal structures, thin-film properties, and field-effect transistor (FET) characteristics of tetrathiafulvalene (TTF) derivatives with two phenyl groups are systematically investigated. The highest mobility, 0.11 cm(2) V(-1) s(-1), is observed in biphenyl-substituted TTF (1). The correlation between the crystal structures and the FET properties demonstrates that good transistor properties are associated with two-dimensional intermolecular interaction, which is achieved when the molecules are standing nearly perpendicular to the substrate. Since these TTF derivatives are strong electron donors, the use of a metallic charge-transfer salt (TTF)(TCNQ) as the source and drain electrodes has resulted in a considerable reduction of the off current (TCNQ: tetracyanoquinodimethane).
RESUMO
Cachexia consists of a constellation of metabolic changes that occur in cancer patients, including the reduction of muscle and fat tissue, asthenia, anorexia, hypoglycemia and hypercalcemia. These syndromes complicate therapeutic intervention and decrease the quality of life of the patient. This review discusses the involvement of cytokines in cancer cachexia and describes the contribution of IL-6 and other cytokines to the wasting of C-26-bearing mice. The neutralization of IL-6 by antibody, or IL-6 receptor antagonism by suramin, significantly reduce the severity of key parameters of cachexia. The participation of several other factors (PGE2, IL-1, IL-10 and TNF-alpha) in the cellular communication between the C-26 tumor cell and tumor-infiltrating macrophages is also described.
Assuntos
Anticorpos/uso terapêutico , Caquexia/prevenção & controle , Citocinas/antagonistas & inibidores , Neoplasias/fisiopatologia , Receptores de Citocinas/antagonistas & inibidores , Suramina/uso terapêutico , Animais , Caquexia/fisiopatologia , Citocinas/fisiologia , Humanos , Interleucina-6/antagonistas & inibidores , Interleucina-6/fisiologia , Camundongos , Camundongos Endogâmicos , Neoplasias Experimentais/fisiopatologia , Receptores de Citocinas/fisiologia , Receptores de Interleucina-6/antagonistas & inibidores , Receptores de Interleucina-6/fisiologiaRESUMO
AS-101 is a tellurium-based compound with known immunomodulating properties. The ability of AS-101 to potentiate the effects of chemotherapeutic drugs and augment cytokine production in vivo has led to clinical trials on AS-101 which are currently being carried out in cancer patients. In the present study we show that AS-101 selectively augments the release of TNF alpha and IL-1 alpha and inhibits the release of IL-10 by lipopolysaccharide (LPS)-stimulated mouse peritoneal macrophages and human monocytes. It does not significantly affect the release of IL-6 or leukemia inhibitory factor (LIF). By itself AS-101 does not induce the release of any of these cytokines. Analysis of IL-10 and TNF alpha RNA levels using semiquantitative PCR reveals that AS-101 blocks the transcription of IL-10 mRNA, but does not significantly affect TNF alpha mRNA. Although both AS-101 and interferon (IFN)-gamma inhibit IL-10, AS-101, unlike IFN-gamma, does not prime macrophages for LPS-induced nitric oxide release and does not appear to significantly affect monocyte HLA-DR expression. Our data suggest that AS-101 is a partial IFN-gamma agonist and may explain the shift toward the release of Th-1 type cytokines observed in AS-101-treated patients.
Assuntos
Adjuvantes Imunológicos/farmacologia , Etilenos/farmacologia , Interleucina-10/antagonistas & inibidores , Interleucina-1/metabolismo , Macrófagos Peritoneais/efeitos dos fármacos , Macrófagos Peritoneais/metabolismo , Monócitos/efeitos dos fármacos , Monócitos/metabolismo , Fator de Necrose Tumoral alfa/metabolismo , Animais , Células Cultivadas , Antígenos HLA-DR/biossíntese , Humanos , Interferon gama/farmacologia , Interleucina-10/genética , Interleucina-10/metabolismo , Lipopolissacarídeos/farmacologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , RNA Mensageiro/biossíntese , Fator de Necrose Tumoral alfa/efeitos dos fármacos , Fator de Necrose Tumoral alfa/genéticaRESUMO
The administration of murine TNF-alpha to colon (C)-26 bearing mice, significantly protects the host against the catabolic effects of the tumor. This effect of exogenous TNF-alpha can be primarily attributed to tumor lysis rather than to a direct anticachectic action. Murine peritoneal macrophages cultured with the C-26 line or with C-26 culture supernatant do not release TNF-alpha in response to LPS stimulation. The reduction in TNF-alpha levels is associated with a significant increase in IL-10 levels. Single cell suspension of freshly disaggregated C-26 tumor (which contains host macrophages), do not produce TNF-alpha but contain significant levels of PGE2 and IL-10. In contrast, PGE2 but not TNF-alpha or IL-10 can be detected in the C-26.IVX cell line that is used to generate tumors in vivo. Neutralizing anti IL-10 Ab but not isotype-matched Ab, significantly reverses the inhibitory effect of the tumor cells and their culture supernatant on macrophage TNF-alpha release. Additional evidence is presented to indicate that the C-26-derived inhibitory activity is related to PGE2. Taken together, these results support the hypothesis that tumor-derived PGE2 prevents tumor-infiltrating macrophages from producing TNF-alpha, in part by augmenting macrophage IL-10 synthesis.
Assuntos
Neoplasias do Colo/imunologia , Dinoprostona/fisiologia , Interleucina-10/imunologia , Macrófagos/imunologia , Fator de Necrose Tumoral alfa/fisiologia , Animais , Anticorpos Monoclonais , Caquexia/imunologia , Células Cultivadas , Meios de Cultivo Condicionados , Ensaio de Imunoadsorção Enzimática , Lipopolissacarídeos/farmacologia , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos DBA , Reação em Cadeia da Polimerase , Células Tumorais Cultivadas , Fator de Necrose Tumoral alfa/biossínteseRESUMO
Several recent reports presented conflicting data on the action of IL-4 and IL-13 in regulating the release of proinflammatory cytokines by human monocytes. Here we show that the regulation of cytokine release by IL-4 and IL-13 could be either inhibitory or stimulatory in LPS-treated murine peritoneal macrophages. When macrophages were treated with IL-13 or IL-4, between 6 and 24 hr prior to endotoxin challenge, TNF alpha and IL-6 levels were significantly augmented. On the other hand, when the cells were cotreated with LPS plus IL-13 or IL-4, the release of TNF alpha and IL-6 was inhibited. These effects of IL-4 and IL-13 were associated with the modulation of IL-10; pretreatment resulted in a decrease, whereas cotreatment gave rise to a dramatic increase in IL-10 levels. The inhibitory effect of IL-4 and IL-13 on the release of TNF alpha was partially reversed by neutralizing anti-IL10 antibody, and the inhibition of IL-6 release was completely reversed by the antibody. These data suggest that the mechanism of action of IL-13 and IL-4 in modulating macrophage TNF alpha and IL-6 release partially involves IL-10.
Assuntos
Adjuvantes Imunológicos/farmacologia , Interleucina-10/metabolismo , Interleucina-13/farmacologia , Interleucina-4/farmacologia , Lipopolissacarídeos/farmacologia , Macrófagos Peritoneais/efeitos dos fármacos , Macrófagos Peritoneais/metabolismo , Animais , Células Cultivadas , Interleucina-10/imunologia , Ativação de Macrófagos/efeitos dos fármacos , Macrófagos Peritoneais/imunologia , Masculino , Camundongos , Camundongos Endogâmicos C57BLRESUMO
CD8(+) T cells are known to down-regulate the TCR complex upon ligation with its cognate MHC class I-peptide complex. In the present report, we demonstrate that stimulation of CD8(+) T cells with cytokines also leads to down-regulation of the TCR complex and TCR-associated surface molecules. A significant reduction of TCRalpha beta, CD3, CD8alpha and CD8beta surface expression was observed when CD8(+) T cells were cultured in IL-2 and to a lesser extent in IL-4 or IL-15. The down-regulation was apparent after 2 days of culture and was observed at IL-2 concentrations as low as 10 U/ml. Using TCR transgenic mice, we found that the down-regulation was associated with a decreased affinity of CD8(+) T cells to MHC class I-peptide complexes, as determined by MHC class I tetramer staining. Furthermore, the antigen-specific proliferation of IL-2-pre-activated CD8(+) T cells was significantly reduced compared to naive CD8(+) T cells or to CD8(+) T cells previously stimulated with peptide-pulsed dendritic cells. Moreover, only CD8alpha(high) but not CD8alpha(low) cells sorted from IL-2-activated CD8(+) T cells proliferated in response to specific antigen, although both subsets proliferated equally well to IL-2. Taken together, these data suggest that the down-regulation of TCR components and a subsequent decrease in affinity towards MHC class I-peptide complexes may be a mechanism by which TCR-dependent proliferation of non-specifically activated CD8(+) T cells is avoided.
Assuntos
Linfócitos T CD8-Positivos/efeitos dos fármacos , Interleucina-2/farmacologia , Receptores de Antígenos de Linfócitos T/análise , Animais , Antígenos CD8/análise , Linfócitos T CD8-Positivos/química , Regulação para Baixo , Antígenos de Histocompatibilidade Classe I/metabolismo , Interleucina-15/farmacologia , Interleucina-4/farmacologia , Ativação Linfocitária , Camundongos , Camundongos Endogâmicos C57BL , Complexo Receptor-CD3 de Antígeno de Linfócitos T/análise , Receptores de Antígenos de Linfócitos T alfa-beta/análiseRESUMO
The biological function of 2B4, a CD48-binding molecule expressed on T cells with an activation/memory phenotype, is not clear. In this report, we demonstrate that proliferation of CD8(+) T cells is regulated by 2B4. Proliferative responses of CD8(+) T cells were significantly reduced by anti-2B4 Ab. The effects were not potentiated by anti-CD48 Ab, suggesting that the observed responses were driven by 2B4/CD48 interactions. Surprisingly, the 2B4/CD48-dependent proliferative responses were also observed in the absence of APCs. This suggests that 2B4/CD48 interactions can occur directly between T cells. Furthermore, when activated 2B4(+)CD8(+) T cells were mixed with 2B4(-)CD8(+) TCR-transgenic T cells and specific peptide-loaded APC, the proliferation of the latter T cells was inhibited by anti-2B4 Ab. Taken together, this suggests that 2B4 on activated/memory T cells serves as a ligand for CD48, and by its ability to interact with CD48 provides costimulatory-like function for neighboring T cells.