RESUMO
In order to asses the role of the soluble mediators of serum from patients with SLE in the apoptotic cell clearance, we measured the in vitro phagocytosis of apoptotic Jurkat cells by normal healthy donor macrophages in the presence of SLE patients' sera. A significant increase of the phagocytic index (NHD = 1.0 +/- 0.3; SLE = 1.9 +/- 0.6; p < 0.01) was to be observed in the presence of serum from patients with SLE. The increased phagocytic index correlated to the anti-dsDNA antibodies titers. We conclude that anti-dsDNA antibodies present in sera of patients with SLE favor the apoptotic cell phagocytosis by opsonization of the target cells. This may represent a deviation of the clearance process towards inflammation and a new pathologic feature of these autoantibodies in SLE.
Assuntos
Anticorpos Antinucleares/imunologia , Apoptose/imunologia , Lúpus Eritematoso Sistêmico/imunologia , Macrófagos/imunologia , Fagocitose/imunologia , Anticorpos Antinucleares/sangue , Humanos , Células Jurkat , Lúpus Eritematoso Sistêmico/sangueRESUMO
Thirty silent lupus nephritis (SLN) patients were compared to 16 individuals bearing overt lupus nephritis (OLN). Results included: years of systemic lupus erythematosus (SLE) diagnosis were significantly earlier (4.6 +/- 2.8 years) in SLN than in OLN (7.18 +/- 3.61) (P < 0.05). Neurological compromise, hypertension, normocitic anemia and lymphopenia were significantly prevalent in OLN than in SLN (P < 0.05). Beside normal urinary sediment and renal function tests, the SLN group showed a moderate increase of both activity (AI) and chronicity (CI) renal pathology index when compared to highly increased AI and CI in OLN (P < 0.05). Seventy percent of SLN patients were ISN/RPS Classes I (6.6%) and II (63.3%) while 81% of OLN cases were Classes III, IV (37.5%) and V. IgG, IgA, IgM, lambda chain, C3 and fibrinogen immune deposits were found in 90% or over in both SLN and OLN individuals while in 60% or over, both groups also showed kappa chain, Clq and C4 deposits. While prevalence of ANA, anti-dsDNA and anti-C1q antibodies were similar in both groups, anti-histone, anti-RNP, CIC and CH50 serum levels were significantly different in OLN versus SLN (P < 0.05). We strongly suggest that indeed SLN is the earliest stage in the natural history of lupus nephritis.
Assuntos
Nefrite Lúpica/imunologia , Nefrite Lúpica/patologia , Adulto , Autoanticorpos/sangue , Biópsia , Complemento C1q/imunologia , Complemento C3/imunologia , DNA/imunologia , Diagnóstico Precoce , Feminino , Fibrinogênio/imunologia , Humanos , Rim/patologia , Nefrite Lúpica/epidemiologia , Masculino , Pessoa de Meia-Idade , Estudos SoroepidemiológicosRESUMO
Silent lupus nephritis (SLN) was investigated in 42 renal asymptomatic patients and compared with 49 untreated patients with overt lupus nephropathy (OLN). Urinary sediment, quantitative proteinuria, creatinine clearance, antinuclear antibodies (ANA), complement, circulating immune complexes (CIC) and renal biopsies were evaluated in all of the patients. Forty-one out of the 42 (97.6%) patients had SLN according to histopathological findings. Results showed that the mean age, female/male ratio and the clinical activity index (SLEDAI) were similar in both groups (P > 0.05). The prevalence of ANA, anti-ds DNA, anti-ENA autoantibodies and C4 serum levels showed no statistical differences between the two groups (P > 0.05). Conversely, in the OLN group, elevated CIC and diminished CH50 and C3 serum levels were significantly different (P < 0.01). WHO class II was the predominant renal lesion in the group with SLN (P < 0.0001), whereas class IV was in the OLN patients (P < 0.0001). We conclude that, in our series, SLN was highly prevalent in renal asymptomatic patients with otherwise systemic lupus erythematosus. Furthermore, abnormal levels of CIC, CH50 and C3 associated with WHO class II suggest a moderate but ongoing activation of immune-mediated renal injury mechanisms.
Assuntos
Glomérulos Renais/patologia , Nefrite Lúpica/patologia , Adolescente , Adulto , Idoso , Biópsia , Criança , Creatinina/metabolismo , Feminino , Humanos , Nefrite Lúpica/epidemiologia , Masculino , Pessoa de Meia-Idade , Necrose , Prevalência , Proteinúria/epidemiologia , Proteinúria/patologiaRESUMO
In order to define an activity profile in patients with multiple sclerosis (MS), T-cell subpopulations and proliferative responses to myelin basic protein (MBP) associated with anti-MBP antibodies, nitrotyrosine levels in serum and cerebrospinal fluid (CSF), and serum CD40L (sCD154) were simultaneously assessed in 29 consecutive and untreated MS patients. When compared to controls, patients in secondary progressive stable (SP/I), or in full remission (RR/I) stages, individuals with secondary progressive active disease (SPIA) or in acute relapse (RR/A) showed a significant decrease of CD4/CD45RA+ T cells associated with an increase of absolute numbers of CD4/45R0+ T cells (p < 0.001). In addition, in vitro-specific T-cell proliferative responses against MBP (SP/A, RR/A, SP/I: p < 0.001 versus controls) in association with augmented sCD154 serum levels (SP/A, RR/A, versus controls p < 0.001) and a significant increase of both CSF and serum levels of anti-MBP antibodies and nitrotyrosine levels (p < 0.001) were also found. Thus, the simultaneous evaluation of antibody and cell-mediated immunopathological parameters, along with the effector mediators of inflammation such as the nitric oxide products, offers a new integrative approach to characterize markers of clinical activity in MS patients, which may be used at the moment of the initial diagnosis and during an apparent recurrences of the disease to monitor therapeutic protocols and to determine whether immune-based nerve destruction mechanisms are still operating in patients with few clinical findings.
Assuntos
Biomarcadores , Esclerose Múltipla/diagnóstico , Esclerose Múltipla/imunologia , Tirosina/análogos & derivados , Adolescente , Adulto , Autoanticorpos/sangue , Autoanticorpos/líquido cefalorraquidiano , Ligante de CD40/sangue , Divisão Celular/imunologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Proteína Básica da Mielina/imunologia , Óxido Nítrico/metabolismo , Projetos Piloto , Estudos Prospectivos , Índice de Gravidade de Doença , Subpopulações de Linfócitos T , Tirosina/sangue , Tirosina/líquido cefalorraquidianoRESUMO
BACKGROUND: Plasma leptin levels in preeclamptic patients have been reported to be similar compared to those of normotensive pregnant women. Nonetheless, no reports have dealt with the effect of antihypertensive treatment and leptin in preeclamptic patients. METHODS: The study involved three groups of a similar age, body mass index and weeks of gestation. The groups were 30 normal pregnant women and 23 pregnant women with severe preeclampsia (SPE). The SPE patients were not treated prior to admission and the treatment was a single dose of alpha-methyldopa or hydralazine alone or in combination. The samples were taken at random in the afternoon (isotonic saline or pharmacological treatment) and 1 h before and after the treatment was given. Leptin serum levels were determined by a commercial sandwich ELISA assay. RESULTS: Leptin levels of the SPE group prior to the treatment were similar to the levels recorded for the normal pregnant women. However, after 1 h leptin levels were significantly higher (p < 0.001) in the nontreated patients (8.0 +/- 1.5) compared with those treated (5.15 +/- 0.9). CONCLUSION: These marked differences between treated and nontreated patients suggest that leptin levels may be modulated by a single antihypertensive treatment in preeclamptic patients with a discrete increase in blood pressure.
Assuntos
Anti-Hipertensivos/uso terapêutico , Leptina/sangue , Pré-Eclâmpsia/tratamento farmacológico , Gravidez/sangue , Adulto , Índice de Massa Corporal , Ensaio de Imunoadsorção Enzimática , Feminino , Idade Gestacional , Humanos , Hidralazina/uso terapêutico , Metildopa/uso terapêuticoRESUMO
A pesar de la numerosa y variada literatura sobre laimportancia de lipoproteínas y de leucocitos en la placa ateromatosa, existen pocos reportes sobre cómo la respuesta inmune es modulada por proteínas plasmáticas y a su vez cómo las células del sistema inmune modifican el anabolismo, catabolismo de éstas. En esta revisión, se hace un análisis de los nuevos enfoques en el estudio de aterosclerosis y la importancia de los leucocitos y el metabolismo de las lipoproteínas plasmáticas en la génesis, progresión e inestabilidad de la placa ateromatosa
Assuntos
Humanos , Masculino , Feminino , Arteriosclerose/patologia , Leucócitos , Lipoproteínas , Medicina , VenezuelaRESUMO
Malaria antibody detection is valuable in providing retrospective confirmation of an attack of malaria. Blood bank screening is another area were malaria serology is potentially useful. In the present study, we tested the presence of antibodies to Plasmodium falciparum in sera from blood bank donors of non-endemic and malaria-endemic areas of Venezuela. Sera from 1,000 blood donors were tested by an indirect immunofluorescent antibody (IFA) assay and an IgG-ELISA for the presence of malaria antibodies using a synchronized in vitro-cultured Venezuelan isolate of P. falciparum as the antigen source. A selected group of positive and negative sera (n = 100) was also tested by a dot-IgG-ELISA. Positive results (reciprocal titer > or = 40) were found in 0.8% and 3.8% of blood donors when tested by the IFA assay and in 0.8% and 2% (optical density > or = 0.2) when tested by the IgG-ELISA in Caracas (non-endemic area) and Bolivar City (endemic area), respectively. The presence of anti-malarial antibodies in some sera from non-endemic areas such as Caracas reflects the increased potential risk of post-transfusional malaria in those areas due to the mobility of the blood donors. The data obtained indicate the need to implement new blood donor policy in blood banks in developing areas. Our results also indicate that the IFA assay is the most reliable test to use in malaria serodiagnosis.
Assuntos
Anticorpos Antiprotozoários/sangue , Doadores de Sangue , Portador Sadio/imunologia , Malária Falciparum/imunologia , Plasmodium falciparum/imunologia , Adolescente , Adulto , Animais , Antígenos de Protozoários/biossíntese , Bancos de Sangue , Western Blotting , Portador Sadio/epidemiologia , Ensaio de Imunoadsorção Enzimática , Reações Falso-Positivas , Feminino , Técnica Indireta de Fluorescência para Anticorpo , Humanos , Malária Falciparum/epidemiologia , Masculino , Pessoa de Meia-Idade , Plasmodium falciparum/isolamento & purificação , Curva ROC , Sensibilidade e Especificidade , Estatísticas não Paramétricas , Venezuela/epidemiologiaRESUMO
A polyclonal CD3(+), CD8(+) T-cell line, G2, was derived from the peripheral blood of a seropositive, PCR-positive, HTLV-IIB infected Guahibo Indian from Venezuela. The cell line is productively infected with HTLV-IIB. The entire HTLV-II G2 proviral DNA was sequenced via PCR using overlapping HTLV-II primer pairs. Phylogenetic analyses indicate that HTLV-II G2 is the most divergent HTLV-IIB strain identified to date. Characterization of its deduced proteins and its relationship to other members of the PTLV/BLV genus of retroviruses are discussed.
Assuntos
Genoma Viral , Vírus Linfotrópico T Tipo 2 Humano/genética , Indígenas Sul-Americanos , Sequência de Aminoácidos , Células Cultivadas , DNA Viral/análise , Vírus Linfotrópico T Tipo 2 Humano/classificação , Vírus Linfotrópico T Tipo 2 Humano/isolamento & purificação , Humanos , Imunofenotipagem , Dados de Sequência Molecular , Homologia de Sequência de Aminoácidos , VenezuelaRESUMO
To evaluate the oxidative burst in hepatitis C virus (HCV) infection, intracellular hydrogen peroxide (H2O2) production of polymorphonuclear (PMN) cells isolated from 15 chronic HCV-infected patients and 11 controls was assessed by flow cytometry in a time kinetic. Under nonstimulated and phorbol myristate acetate (PMA)-stimulated conditions, H2O2 production was higher in HCV-infected patients than in controls (P <0.05) at the time points of 20, 30, and 40 min. A positive correlation between H2O2 production by PMA-stimulated cells and serum levels of alanine aminotransferase and aspartate aminotransferase was found in the HCV-infected patients (r = 0.877, P <0.01 and r = 0.9351, P <0.001, respectively). RT-PCR analysis of purified mononuclear (MN) and PMN cells from HCV-infected patients revealed the presence of HCV RNA in 60% of MN and 27% of PMN cell samples. These results suggest that a functional alteration of PMN cells is manifested in this chronic viral infection which may represent an additional factor in the development of liver lesions.
Assuntos
Hepatite C Crônica/metabolismo , Peróxido de Hidrogênio/metabolismo , Neutrófilos/metabolismo , Adulto , Feminino , Hepatite C Crônica/genética , Humanos , Leucócitos Mononucleares/metabolismo , Leucócitos Mononucleares/virologia , Masculino , Pessoa de Meia-Idade , Neutrófilos/efeitos dos fármacos , Neutrófilos/virologia , RNA/análise , Explosão Respiratória/efeitos dos fármacos , Explosão Respiratória/imunologia , Acetato de Tetradecanoilforbol/farmacologiaRESUMO
The peripheral blood of 41 Yaruro and Guahibo Indians from Venezuela was examined for HTLV antibodies and DNA. Twenty-five samples (61%) were found to be infected with HTLV-IIB. The sensitivities of the serologic and DNA polymerase chain reaction (PCR) analyses were 80% and 96%, respectively. Epidemiologic studies supported both sexual and perinatal transmission of the virus. Sequence analyses of the HTLV-IIB strains from these Indians indicate that they are unique relative to HTLV-II detected in other groups of humans. HTLV-IIB-G2 isolated from a Guahibo Indian is the most divergent HTLV-IIB strain relative to the prototype HTLV-II NRA.
Assuntos
Infecções por HTLV-II/etnologia , Vírus Linfotrópico T Tipo 2 Humano/genética , Indígenas Sul-Americanos , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Animais , Sequência de Bases , Cricetinae , Transmissão de Doença Infecciosa , Infecções por HTLV-II/genética , Infecções por HTLV-II/transmissão , Vírus Linfotrópico T Tipo 2 Humano/classificação , Humanos , Transmissão Vertical de Doenças Infecciosas , Pessoa de Meia-Idade , Dados de Sequência Molecular , Linhagem , Filogenia , Reação em Cadeia da Polimerase , Prevalência , Homologia de Sequência do Ácido Nucleico , Estudos Soroepidemiológicos , Venezuela/epidemiologiaRESUMO
Natural killer (NK) cells were shown to secrete differentially interleukins (IL), IL-1 alpha, IL-1 beta, IL-2, IL-8, interferon-gamma (IFN-gamma), tumour necrosis factor-alpha (TNF-alpha), granulocyte-macrophage colony-stimulating factor (GM-CSF), and leukaemia inhibitory factor (LIF) upon stimulation with optimal concentrations of chylomicrons (CM), very-low-density lipoprotein (VLDL), low-density lipoprotein (LDL), high-density lipoprotein (HDL) or acetyl-modified low-density lipoprotein (AcLDL). CM, VLDL, LDL and AcLDL induced LIF secretion which was absent in nonstimulated cells. CM, VLDL, and LDL did not affect IL-1 alpha secretion. CM stimulated IL-8 > TNF-alpha > IL-1 alpha > IL-2 = IFN-gamma, and decreased seventeen-fold GM-CSF secretion. VLDL stimulated IL-8 secretion > IL-1 alpha = IL-2 > IFN-gamma > TNF-alpha and decreased fivefold GM-CSF secretion. LDL stimulated IL-8 secretion > IL-1 alpha > IL-2 = IFN-gamma, it did not modify TNF-alpha and inhibited five hundred-fold GM-CSF secretion. HDL stimulated IL-2 secretion = IFN-gamma > IL-8, it decreased GM-CSF secretion > IL-1 alpha > IL-1 beta > TNF-alpha without affecting LIF. AcLDL stimulated IL-8 secretion > TNF-alpha > IL-1 alpha > IL-2 = IFN-gamma = IL-1 beta, and decreased GM-CSF secretion eightfold. When NK cells were primed with 10, 100 or 500 IU/ml of IL-2 before the addition of lipoproteins, a decrease in the secretion of cytokines was observed as compared with cells primed with IL-2 only. Differences in cytokine secretion were observed among the diverse type of lipoproteins used for cell stimulus. Thus, lipoproteins may condition NK cytokine secretion and cell activation.
Assuntos
Citocinas/biossíntese , Interleucina-2/imunologia , Células Matadoras Naturais/metabolismo , Lipoproteínas/imunologia , Técnicas de Cultura de Células , Fator Estimulador de Colônias de Granulócitos e Macrófagos/biossíntese , Humanos , Interferon gama/biossíntese , Interleucinas/biossíntese , Células Matadoras Naturais/imunologia , Fator de Necrose Tumoral alfa/biossínteseRESUMO
1. Serum nitric oxide (NO) levels (determined by its products of oxidation) were assessed in non-pregnant women, normal pregnant women and patients suffering from mild pre-eclampsia (MPE), severe pre-eclampsia (SPE), chronic hypertension (CHT) and CHT with pre-eclampsia (CHT + PE). The levels of NO products were significantly reduced during pregnancy in MPE (P < 0.001), CHT + PE (P < 0.01) and SPE (P < 0.05). Significant reductions of NO products were also observed in puerperium (P < 0.001) in all groups except CHT + PE (P < 0.05). 2. In normal pregnancy, three events were related to NO levels: (1) negative correlations were found between the levels of nitrite (r = -0.73, P = 0.0003), nitrate (r = -0.53, P = 0.017) and the number of weeks of gestation; (2) in the caesarean section group, the levels of NO at puerperium were significantly lower (P < 0.05) than those during pregnancy; and (3) there was a significant reduction in NO levels in the pregnant women carrying male fetuses as compared with female fetuses (P < 0.05). 3. In SPE, the patients with a family history of hypertension had lower levels of NO compared with the patients without such a history (P < 0.05). 4. A negative correlation was observed between systolic blood pressure, diastolic blood pressure and NO levels in MPE (r = -0.62, P = 0.013 and r = -0.68, P = 0.0049 respectively) and SPE (r = -0.72, P = 0.004 and r = -0.53, P = 0.037 respectively). 5. In SPE, positive correlations were observed between platelet count and nitrite (r = 0.67, P = 0.006) and nitrate levels (r = 0.56, P = 0.028). 6. In MPE, patients with anti-hypertensive treatment showed significantly (P < 0.05) higher levels of NO compared with the non-treated patients. 7. NO may be important in the physiopathology of hypertension during pregnancy, although several factors may affect its levels.
Assuntos
Hipertensão/sangue , Óxido Nítrico/sangue , Complicações Cardiovasculares na Gravidez/sangue , Adulto , Anti-Hipertensivos/uso terapêutico , Feminino , Humanos , Hipertensão/tratamento farmacológico , Nitratos/sangue , Nitritos/sangue , Contagem de Plaquetas , Período Pós-Parto/sangue , Pré-Eclâmpsia/sangue , Pré-Eclâmpsia/tratamento farmacológico , Gravidez , Complicações Cardiovasculares na Gravidez/tratamento farmacológico , Fatores SexuaisRESUMO
Sera from 166 Guahibo Indians (55% of the population) living in southwest Venezuela were screened by enzyme-linked immunoassay for antibodies to human T-cell lymphotropic virus (HTLV) I and II. Positive samples were confirmed by immunofluorescence and Western blot. Forty-one Guahibos (24.8%) were found to be seropositive. Polymerase chain reaction (PCR) analysis of proviral DNA in mononuclear cell lysates revealed the virus to be HTLV-II. Prevalence increased with age, and sexual contact with HTLV-II-seropositive partners was identified as a risk factor for infection. PCR amplification of a region of the pol gene, utilizing the primer pair SK110/SK111, with subsequent digestion of the 140-base-pair amplification products with HinfI and MseI restriction enzymes, showed an HTLV-II subtype-b restriction pattern in all cases. These data suggest that the substrain infecting this Guahibo community belongs to the b subtype, the most frequent among Paleo-Amerindian populations.
Assuntos
Infecções por HTLV-II/epidemiologia , Vírus Linfotrópico T Tipo 2 Humano/isolamento & purificação , Adolescente , Adulto , Fatores Etários , Idoso , Western Blotting , Criança , Pré-Escolar , DNA Viral/análise , Feminino , Genes pol , Infecções por HTLV-II/genética , Infecções por HTLV-II/imunologia , Vírus Linfotrópico T Tipo 1 Humano/imunologia , Vírus Linfotrópico T Tipo 2 Humano/genética , Vírus Linfotrópico T Tipo 2 Humano/imunologia , Humanos , Indígenas Sul-Americanos , Masculino , Pessoa de Meia-Idade , Reação em Cadeia da Polimerase , Polimorfismo de Fragmento de Restrição , Prevalência , Fatores de Risco , Estudos Soroepidemiológicos , Comportamento Sexual , Venezuela/epidemiologiaRESUMO
The clinical and public health importance of CD4+ T lymphocytopenia without human immunodeficiency virus infection is still unclear. We describe herein two new human immunodeficiency virus-negative patients with low numbers of peripheral CD4+ T cells and opportunistic infections (cerebral toxoplasmosis and tuberculosis plus extrapulmonary histoplasmosis). The low numbers of CD4+ CD29+ memory cells, the high percentage of gamma delta T-cell receptor cells, and the recovery of CD4+ cells after treatment were remarkable.
Assuntos
Subpopulações de Linfócitos T/imunologia , T-Linfocitopenia Idiopática CD4-Positiva/imunologia , Adulto , Antígenos CD4/imunologia , Linfócitos T CD4-Positivos/imunologia , Feminino , Humanos , Integrina beta1/imunologia , Masculino , Pessoa de Meia-Idade , Receptores de Antígenos de Linfócitos T gama-delta/imunologia , T-Linfocitopenia Idiopática CD4-Positiva/terapiaRESUMO
Immunoglobulin (Ig) isotype (IgG, IgG1, IgG2, IgG3, IgG4, IgM, IgD and IgE) levels were investigated, both pre- and post-treatment with praziquantel (PZQ), in 43 adults and children chronically infected with Schistosoma mansoni, by means of a two-site, isotype-specific immunoenzymometric assay. The patients were classified as responders (R) or non-responders (NR) on the basis of their circumoval precipitin test (COPT) results 12 months after treatment. In comparison with controls, pre-treatment R children showed significantly higher levels of IgG, IgG1, IgG4 (p < 0.001) and IgE (p < 0.01); and diminished IgG2 (p < 0.05), while NR children showed significantly elevated levels only of IgE (p < 0.05). Twelve months after therapy, R children maintained significantly lower levels of IgG2, but showed significantly decreased levels of IgG, IgG1, IgG4, and IgE, while the Ig isotype profile of NR children was unaltered. Adult R and NR showed similar isotype profiles before chemotherapy, with the exception of significantly elevated IgM levels in R. Twelve months after therapy, R adults showed significantly decreased levels of IgG, IgG1, and IgG4, while NR adults showed only diminished IgG4 levels. These results reveal different Ig isotype profiles in untreated adults and children chronically infected with S. mansoni. The results further show that the pre-treatment Ig isotype profile may be significantly modified after an effective R to chemotherapy, accounted for by down regulation of the IgG1 isotype in association with negative seroconversion of the COPT in R patients. The COPT reaction has been associated with the highly specific egg glycoprotein antigen omega 1, which shows a significant reduction in reactivity six months after treatment. IgG1 may thus play a main role in the response against the omega 1 antigen.
Assuntos
Antiplatelmínticos/farmacologia , Isotipos de Imunoglobulinas/efeitos dos fármacos , Praziquantel/farmacologia , Esquistossomose mansoni/tratamento farmacológico , Esquistossomose mansoni/imunologia , Adolescente , Adulto , Antiplatelmínticos/uso terapêutico , Criança , Humanos , Imunoglobulina G/sangue , Imunoglobulina G/efeitos dos fármacos , Isotipos de Imunoglobulinas/sangue , Praziquantel/uso terapêutico , Esquistossomose mansoni/sangueRESUMO
Lipoprotein lipase (LPL) induced, in a dose-dependent fashion, a 2-fold and 11-fold increase in the proliferative response of peripheral blood lymphocytes (PBL) at 48 and 72 h, respectively; a 4- and 12-fold increase in natural killer (NK) cells, respectively; and a maximal 3-fold induction in interleukin-2 (IL-2)-treated NK cells at 72 h. T lymphocytes did not proliferate independently of the concentration of LPL used. LPL decreased the proliferative response of K562 and U937 cell lines. The effect on NK cells could be blocked by anti-LPL if it was added before LPL binding to the cell membrane. Contrary to its effects on NK proliferative response, LPL inhibited spontaneous cytotoxicity and lymphokine-activated killer activity (LAK). The effect was dose-dependent, target-dependent (U937 was more sensitive than K562 in LAK assays), but not LPL-binding time-dependent. Treatment of NK cells with heparinase overcame the inhibitory effect of LPL in spontaneous cytotoxicity. LPL binding to cell membranes, as assessed by flow cytometry, was as follows: K562 cells > monocytes > NK cells > LAK cells > U937 cells, absent in T lymphocytes and partially sensible to heparinase and IL-2 treatments. Protein kinase C translocation was observed upon treatment of NK cells with LPL. Three proteins in NK cell membrane (76, 57.2, and 27.2 kD), two in the cytosol (57.2 and 27.2 kD), and only one in ANA-1 cell membrane (76 kD) were precipitated with LPL-Sepharose. LPL receptors seem to be responsible for the proliferative and cytotoxic response observed in LPL-stimulated NK cells.
Assuntos
Citotoxicidade Imunológica/efeitos dos fármacos , Células Matadoras Naturais/efeitos dos fármacos , Lipase Lipoproteica/farmacologia , Ativação Linfocitária/efeitos dos fármacos , Receptores de Superfície Celular/metabolismo , Membrana Celular/metabolismo , Relação Dose-Resposta a Droga , Heparina Liase , Humanos , Interleucina-2/farmacologia , Células Matadoras Ativadas por Linfocina/efeitos dos fármacos , Lipase Lipoproteica/metabolismo , Polissacarídeo-Liases/farmacologia , Ligação Proteica , Proteína Quinase CRESUMO
Low-density lipoprotein receptors (LDLR) have been shown to be expressed, internalized, and transcribed in CD3-CD16+CD56+ cells. Only a low percentage (up to 12%) of NK cells express LDLR. Interleukin 2 (IL-2) (1000 IU/ml) induced a threefold increase in the expression of LDLR on the cell surface that results from, at least in part, augmentation of LDLR turnover from the cytosol to the membrane. Scatchard analysis revealed that IL-2 decreased the Kd of LDLR binding for LDL from 7.53 to 4.33 nM with an increment in the number of binding sites from 2500 up to 5000. Both the proliferative response and cytotoxic functions of these cells are affected by LDL. Low concentrations of LDL induce an increase in the proliferative response (up to eightfold) and in the cytotoxic response of NK cells (up to fivefold). High concentration (more than 60 micrograms/ml) of LDL hampers both proliferative response and cytotoxic activity of NK cells. LDL did not affect the cytotoxic functions of IL-2-activated NK cells. Overall, we have shown that LDLR is expressed on the surface of NK cells and can be augmented by IL-2. Furthermore, we propose some insights into the mechanism responsible for the enhanced expression of LDLR on NK cell surface. In addition, our data clearly delineate that LDLR plays an important role in the regulation of proliferative responses and cytotoxic activity of these cells.
Assuntos
Complexo CD3/análise , Antígeno CD56/análise , Interleucina-2/farmacologia , Células Matadoras Naturais/química , Receptores de IgG/análise , Receptores de LDL/análise , Humanos , Lipoproteínas LDL/metabolismo , Ativação Linfocitária , Receptores de LDL/fisiologiaRESUMO
We previously showed that T cells from chronic nonviremic HBsAg carriers activated with immobilized OKT3 MAb are hyperreactive to monocyte accessory signals, mainly to interleukin-6 (IL-6). We have further characterized this T cell hyperreactivity using phytohemagglutinin (PHA) as the primary activating signal. PHA-stimulated T cells from nonviremic patients had a significantly higher response to addition of monocytes, monocyte supernatants, and IL-6 alone or combined with IL-1 beta when compared to controls. We examined if these effects could be mediated by a differential expression of IL-6 receptor (p80) or gp130 on resting or PHA-stimulated T cells. We found that PHA, IL-6, IL-1 beta, or IL-2 induced only small changes of the dull p80 expression on T cells. In contrast, we found a significant increase of gp130 expression on PHA-activated T cells compared to unstimulated T cells, which was down-regulated by the presence of IL-6. However, no significant differences in p80 or gp130 expression were detected between patients and controls within all the culture conditions tested. Our results confirm that IL-6 is involved in the in vitro T cell hyperreactivity of nonviremic HBV carriers and indicate that this effect is not mediated by disturbances of IL-6 receptor expression.
Assuntos
Antígenos CD/imunologia , Portador Sadio/imunologia , Vírus da Hepatite B/imunologia , Hepatite B/imunologia , Interleucina-6/imunologia , Glicoproteínas de Membrana/imunologia , Receptores de Interleucina/imunologia , Linfócitos T/imunologia , Adulto , Divisão Celular , Células Cultivadas , Doença Crônica , Técnicas de Cocultura , Receptor gp130 de Citocina , Citocinas/imunologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Monócitos/citologia , Monócitos/imunologia , Fito-Hemaglutininas/farmacologia , Receptores de Interleucina-6 , Linfócitos T/efeitos dos fármacos , ViremiaRESUMO
Natural killer (NK) cells take up chylomicrons (CM), very low density (VLDL), low density (LDL), high density (HDL) and acetyl-modified low density (AcLDL) lipoproteins through different receptors, VLDL being the lipoprotein with the highest uptake and HDL the lowest. The uptake of LDL can be selectively blocked by the anti-LDL receptor, which does not affect the uptake of CM, VLDL, HDL and AcLDL. Although the uptake of lipoproteins assessed by flow cytometry using DiI is not very high, the lipoproteins are able to induce an increase in proliferative responses, VLDL, AcLDL and HDL being the most important ones with 12- and 17-fold increments, respectively. CM, VLDL and LDL at low concentrations increase NK cytotoxic activity, while HDL and AcLDL inhibit, in a dose-dependent fashion, the killing of NK cells against K562. These results suggest the presence of four different receptors that are responsible for the cytotoxic and proliferative responses observed.
Assuntos
Células Matadoras Naturais/metabolismo , Receptores de Lipoproteínas/metabolismo , Acetilação , Células Cultivadas , Quilomícrons/metabolismo , Quilomícrons/farmacologia , Citotoxicidade Imunológica , Relação Dose-Resposta a Droga , Citometria de Fluxo , Humanos , Imunidade Celular , Células Matadoras Naturais/imunologia , Lipoproteínas HDL/metabolismo , Lipoproteínas HDL/farmacologia , Lipoproteínas LDL/metabolismo , Lipoproteínas LDL/farmacologia , Lipoproteínas VLDL/metabolismo , Lipoproteínas VLDL/farmacologiaRESUMO
A double-blind, cross-over protocol was applied to 22 asthmatic patients who were previously subjected to provocation tests with methacholine. The baseline FEV1 for mild asthma was 89.6 +/- 13.6% while for moderate asthma it was 73 +/- 6%. The initial provocation tests with methacholine revealed that the mild asthma group needed a greater accumulated dose of methacholine than that required by the moderate asthma group to lower the FEV1 by 20%, stressing the enhanced bronchial hyperreactivity present in the latter group. Significant differences in the PD20 values were obtained in both groups of patients using the combination of salbutamol plus beclomethasone. Salbutamol alone was ineffective to change the PD20 values in mild asthma while beclomethasone alone was able to change significantly the PD20 values in these patients, stressing the importance of the inflammatory component in the pathogenesis of stable asthma. Furthermore, the combination of both drugs was also more effective in the moderate asthma group than either medication alone, confirming the pharmacological control of the obstructive and inflammatory changes that are already established in patients with moderate asthma.