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1.
J Dairy Sci ; 103(2): 1110-1119, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31785881

RESUMO

The consumption of probiotic-enriched dairy products has been associated with many health benefits, including anti-hyperglycemic activity. The effect on health is dependent on the type of probiotic culture used and the dairy product consumed. This study evaluated the effect of different probiotic-enriched dairy matrices (Minas Frescal cheese, Prato cheese, and whey dairy beverage) containing Lactobacillus casei on in vitro and in vivo anti-hyperglycemic activity. For this purpose, in vitro anti-hyperglycemic activity was determined by the inhibition of α-glucosidase and α-amylase activities, and a human study was performed with healthy individuals (n = 15, consumption of bread as a control; bread + Minas Frescal cheese; bread + Prato cheese; bread + dairy beverage) to assess the effects of different probiotic foods on postprandial glycemia. In vitro data showed that Prato cheese presented the highest lipid (36.9 g/100 g) and protein (26.5 g/100 g) contents as well as the highest α-amylase (60.7%) and α-glucosidase (52.6%) inhibition. The consumption of Prato cheese resulted in a lesser increase in blood glucose level (13 mg/dL) compared with the consumption of bread alone (19 mg/dL), Minas Frescal cheese (20 mg/dL), and whey dairy beverage (30 mg/dL), with glycemic indices similar to that observed for the control. The present results demonstrated a good correlation between in vitro and in vivo data, in which the type of dairy matrix affects the anti-hyperglycemic activity. It is concluded that the consumption of probiotic Prato cheese can contribute to the reduction of postprandial glycemia in healthy individuals.


Assuntos
Glicemia/metabolismo , Laticínios , Hiperglicemia/prevenção & controle , Período Pós-Prandial , Probióticos , Adulto , Animais , Queijo , Feminino , Índice Glicêmico , Humanos , Hiperglicemia/sangue , Lacticaseibacillus casei/metabolismo , Masculino , Pessoa de Meia-Idade , Adulto Jovem
2.
J Dairy Sci ; 102(12): 10724-10736, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31521367

RESUMO

This study was aimed at developing a new functional fermented beverage manufactured with semi-skimmed sheep milk and strawberry pulp (Fragaria × ananassa Duch.) and commercial prebiotic ingredients. We also compared the performance of the yogurt starter cultures and a Lactobacillus plantarum strain (CECT_8328) with potential probiotic properties. We assessed the nutritional profile, bioactivity compounds, viability of lactic acid bacteria during storage, and survival of L. plantarum after in vitro simulated digestion during the storage period. The lactic acid bacteria were viable throughout the storage period, but only L. plantarum maintained good viability after simulated digestion. Nevertheless, neither inulin nor potato starch increased bacterial viability. The fermented semi-skimmed sheep milk strawberry beverages we developed are good sources of minerals and proteins.


Assuntos
Bebidas , Fragaria , Leite , Animais , Bebidas/microbiologia , Proteínas Alimentares , Fermentação , Inulina/metabolismo , Lactobacillales/metabolismo , Lactobacillus plantarum , Leite/metabolismo , Valor Nutritivo , Prebióticos , Probióticos , Ovinos , Iogurte/microbiologia
3.
J Dairy Sci ; 102(8): 6756-6765, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31178187

RESUMO

Fermented whey dairy beverages are dairy products obtained by fermentation from a mixture of milk and whey. These beverages have important health benefits, which could be improved with the addition of probiotic cultures. This study assessed the protective effect of the cosupplementation of a probiotic culture (Lactobacillus casei 01) with a fermented whey dairy beverage against infection by Salmonella enterica ssp. enterica serovar Typhimurium in a murine model. Two fermented whey dairy beverages were prepared: conventional (FWB; starter culture) and probiotic (PFWB; starter and probiotic cultures). In the first set of experiments, Balb/C female mice were treated with FWB or PFWB, challenged with Salmonella Typhimurium, and analyzed for clinical signs, weight loss, and mortality for 20 d postinfection. In the second set of experiments, mice were treated with FWB or PFWB, challenged with Salmonella Typhimurium, and killed on d 10 postinfection. The liver, colon, and ileum were used for myeloperoxidase, eosinophil peroxidase, and histological analysis and translocation to the liver. The contents from the small intestine were used for secretory IgA determination. The FWB treatment showed a better effect on animal survival (70%), translocation of the pathogen to the liver (2 out of 10), histopathology (fewer lesions), and inflammation than PFWB, which presented 50% animal survival, translocation in 5 out of 10 animals, and higher lesions. The control group presented 40% animal survival, translocation in 6 out of 10 animals, and severe lesions. Therefore, FWB was deemed to have a greater protective effect against Salmonella Typhimurium infection in the murine model compared with PFWB.


Assuntos
Produtos Fermentados do Leite , Salmonelose Animal/prevenção & controle , Salmonella typhimurium , Soro do Leite , Animais , Bebidas , Feminino , Promoção da Saúde , Imunoglobulina A Secretora/análise , Inflamação/prevenção & controle , Intestino Delgado/imunologia , Intestino Delgado/patologia , Lacticaseibacillus casei/fisiologia , Fígado/microbiologia , Fígado/patologia , Camundongos , Camundongos Endogâmicos BALB C , Probióticos , Salmonelose Animal/imunologia , Salmonelose Animal/patologia , Proteínas do Soro do Leite
4.
J Dairy Sci ; 100(8): 6100-6110, 2017 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-28571992

RESUMO

We investigated the performance of multidimensional alignment analysis and multidimensional scaling on phi coefficient values to evaluate check-all-that-apply questionnaire data. We evaluated 6 dairy foods belonging to the category of requeijão cremoso processed cheese (traditional, with starch, or with starch and vegetable fat). We obtained sensory descriptors using trained assessors in descriptive analysis for comparison. A check-all-that-apply questionnaire used with 121 consumers (77 women and 44 men; 18 to 57 yr old) proved to be a suitable alternative for sensory profiling, providing descriptions similar to descriptive analysis and discriminating between products. Multidimensional alignment analysis and multidimensional scaling were efficient and logical approaches for obtaining a deeper understanding of the data, allowing us to clarify the relationships between sensory descriptors and products and contribute to optimizing the different formulations of requeijão cremoso.


Assuntos
Queijo , Comportamento do Consumidor/estatística & dados numéricos , Preferências Alimentares , Paladar , Adulto , Animais , Queijo/análise , Laticínios , Emulsões , Feminino , Manipulação de Alimentos , Humanos , Masculino , Pessoa de Meia-Idade , Reologia , Amido , Estatística como Assunto , Adulto Jovem
5.
Compr Rev Food Sci Food Saf ; 16(2): 247-262, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33371538

RESUMO

Sheep milk has a high nutritional value and high concentrations of proteins, fats, minerals, and vitamins, as compared to the milks of other domestic species. The physicochemical and nutritional characteristics of sheep milk can be advantageous for the manufacture of products containing prebiotic ingredients and/or probiotic bacteria, which are major categories in the functional food market. Following this technological trend, this review will address the characteristics and advantages of sheep milk as a potentially functional food, as well as the development of sheep milk dairy products containing prebiotics and/or probiotics.

6.
J Dairy Sci ; 98(3): 1443-54, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-25557891

RESUMO

Dulce de leche samples available in the Brazilian market were submitted to sensory profiling by quantitative descriptive analysis and acceptance test, as well sensory evaluation using the just-about-right scale and purchase intent. External preference mapping and the ideal sensory characteristics of dulce de leche were determined. The results were also evaluated by principal component analysis, hierarchical cluster analysis, partial least squares regression, artificial neural networks, and logistic regression. Overall, significant product acceptance was related to intermediate scores of the sensory attributes in the descriptive test, and this trend was observed even after consumer segmentation. The results obtained by sensometric techniques showed that optimizing an ideal dulce de leche from the sensory standpoint is a multidimensional process, with necessary adjustments on the appearance, aroma, taste, and texture attributes of the product for better consumer acceptance and purchase. The optimum dulce de leche was characterized by high scores for the attributes sweet taste, caramel taste, brightness, color, and caramel aroma in accordance with the preference mapping findings. In industrial terms, this means changing the parameters used in the thermal treatment and quantitative changes in the ingredients used in formulations.


Assuntos
Comportamento de Escolha , Comportamento do Consumidor , Laticínios , Preferências Alimentares , Brasil , Doces , Carboidratos , Análise por Conglomerados , Cor , Humanos , Análise dos Mínimos Quadrados , Modelos Logísticos , Odorantes , Análise de Componente Principal , Olfato , Paladar
7.
J Dairy Sci ; 94(11): 5330-40, 2011 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-22032355

RESUMO

This study aimed to evaluate the quality of stirred-type skim milk probiotic yogurt fortified by partially replacing skim milk powder (SMP) with whey protein concentrate (WPC) and sodium caseinate (Na-CN) during cold storage for 28 d compared with nonfortified yogurt. The rheological properties (as measured using dynamic oscillation) and sensory profiles of probiotic yogurts were greatly enhanced when SMP (i.e., 45%) was replaced with WPC and Na-CN. Higher values of mechanical parameters related to storage and loss modulus and consistent microstructure were found in the fortified yogurts. The acidification profile was not affected by supplementation of the solids in the milk base, and the viable counts of probiotic microbiota were high and satisfactory. These positive characteristics of probiotic yogurts were maintained until the end of the storage period. The microstructure of the fortified yogurt showed some differences compared with the nonfortified product, which were due to changes in chemical composition of the milk base in addition to the colloidal characteristics of the product.


Assuntos
Temperatura Baixa , Manipulação de Alimentos , Probióticos , Iogurte/análise , Iogurte/normas , Animais , Carga Bacteriana , Caseínas/química , Laticínios/análise , Humanos , Concentração de Íons de Hidrogênio , Microscopia Eletrônica de Varredura , Leite/química , Proteínas do Leite/química , Pós/análise , Reologia , Paladar , Fatores de Tempo , Proteínas do Soro do Leite , Iogurte/microbiologia
8.
J Dairy Sci ; 94(6): 2701-6, 2011 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-21605739

RESUMO

We investigated the effect of sodium reduction by partial substitution of sodium chloride (NaCl) with potassium chloride (KCl) on the manufacture of Minas fresh cheese during 21 d of refrigerated storage. Four treatments of low-sodium Minas fresh cheese were manufactured, with partial replacement of NaCl by KCl at 0, 25, 50, and 75% (wt/wt), respectively. The cheeses showed differences in the content of moisture, ash, protein, salt, and lipid contents, as well as on the extent of proteolysis and hardness throughout the storage period. However, no difference was observed among treatments within each storage day tested. The partial substitution of NaCl by KCl decreased up to 51.8% the sodium concentration of the cheeses produced. The consumer test indicated that it is possible to manufacture a low-sodium Minas fresh cheese that is acceptable to consumers by partial substitution of NaCl by KCl at 25% (wt/wt) in the salting step.


Assuntos
Queijo/análise , Manipulação de Alimentos/métodos , Cloreto de Potássio , Sódio na Dieta/análise , Animais , Fenômenos Químicos , Paladar
9.
J Dairy Sci ; 93(11): 5059-68, 2010 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-20965320

RESUMO

Exposure to oxygen may induce a lack of functionality of probiotic dairy foods because the anaerobic metabolism of probiotic bacteria compromises during storage the maintenance of their viability to provide benefits to consumer health. Glucose oxidase can constitute a potential alternative to increase the survival of probiotic bacteria in yogurt because it consumes the oxygen permeating to the inside of the pot during storage, thus making it possible to avoid the use of chemical additives. This research aimed to optimize the processing of probiotic yogurt supplemented with glucose oxidase using response surface methodology and to determine the levels of glucose and glucose oxidase that minimize the concentration of dissolved oxygen and maximize the Bifidobacterium longum count by the desirability function. Response surface methodology mathematical models adequately described the process, with adjusted determination coefficients of 83% for the oxygen and 94% for the B. longum. Linear and quadratic effects of the glucose oxidase were reported for the oxygen model, whereas for the B. longum count model an influence of the glucose oxidase at the linear level was observed followed by the quadratic influence of glucose and quadratic effect of glucose oxidase. The desirability function indicated that 62.32 ppm of glucose oxidase and 4.35 ppm of glucose was the best combination of these components for optimization of probiotic yogurt processing. An additional validation experiment was performed and results showed acceptable error between the predicted and experimental results.


Assuntos
Manipulação de Alimentos/métodos , Microbiologia de Alimentos , Glucose Oxidase/metabolismo , Probióticos/metabolismo , Iogurte/microbiologia , Bifidobacterium/crescimento & desenvolvimento , Contagem de Colônia Microbiana , Oxigênio/metabolismo
10.
Food Res Int ; 91: 38-46, 2017 01.
Artigo em Inglês | MEDLINE | ID: mdl-28290325

RESUMO

The objective of this study was to assess the effects of different prebiotic dietary oligosaccharides (inulin, fructo-oligosaccharide, galacto-oligossacaride, short-chain fructo-oligosaccharide, resistant starch, corn dietary oligosaccharide and polydextrose) in non-fat sheep milk ice cream processing through physical parameters, water mobility and thermal analysis. Overall, the fat replacement by dietary prebiotic oligosaccharides significantly decreased the melting time, melting temperature and the fraction and relaxation time for fat and bound water (T22) while increased the white intensity and glass transition temperature. The replacement of sheep milk fat by prebiotics in sheep milk ice cream constitutes an interesting option to enhance nutritional aspects and develop a functional food.


Assuntos
Manipulação de Alimentos/métodos , Alimento Funcional/análise , Sorvetes/análise , Leite , Oligossacarídeos/análise , Prebióticos/análise , Ovinos , Animais , Gorduras na Dieta/análise , Manipulação de Alimentos/normas , Qualidade dos Alimentos , Congelamento , Alimento Funcional/normas , Sorvetes/normas , Leite/normas , Valor Nutritivo , Oligossacarídeos/normas , Prebióticos/normas , Controle de Qualidade , Temperatura de Transição
11.
Food Res Int ; 90: 275-280, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-29195882

RESUMO

The viability and survival of Lactobacillus acidophilus La5 under in vitro simulated gastrointestinal in probiotic dairy dessert was assessed. In addition, the effects of regular consumption of the dessert (5g/day) on the lipid profile, immune system, and antioxidant/biochemical status of Wistar rats were also evaluated after 2weeks of treatment. Adequate counts of L. acidophilus La-5 were observed regards the viability and gastrointestinal conditions. The probiotic dairy dessert was efficient in reducing the LDL-cholesterol, triacylglycerol and increased the HDL-cholesterol in serum. Aspartate amino transferase, alanine aminotransferase, total protein, albumin, heat shock proteins, immune system responses, and blood-cells counts (monocyte, lymphocyte, neutrophil and leucocyte) were not affected (p>0.05) after 15days of treatment. Overall, the probiotic dairy dessert may be a viable alternative to enhance the blood lipid profile and could be used to improve the antioxidant defenses.

12.
Mol Immunol ; 24(8): 849-55, 1987 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-3116410

RESUMO

Since secretion of IgE antibodies is known to be blocked by tunicamycin, the first aim of the present study was to determine at which step of glycosylation or processing secretion was restored. For this purpose, murine hybridoma cells secreting an anti beta-lactoglobulin IgE were incubated either in the presence of inhibitors of glucosidase I (castanospermine or N-methyl-1-deoxynojirimycin), or of an inhibitor of Golgi mannosidase II (swainsonine). Terminal galactoses predominate on the native IgE N-linked carbohydrate chains. The action of the trimming inhibitors, which results in changes in these terminal galactose residues, was monitored through detecting binding modifications to Concanavalin A and to the lectin of Ricinus communis. The antibody activity was also evaluated by a radioimmunoassay. It was shown that neither secretion nor anti beta-lactoglobulin activity of the IgE antibody are modified in the presence of any of the trimming inhibitors, whereas secretion is blocked in the presence of tunicamycin. Other biological activities of this IgE were investigated: no difference was observed in the binding of the carbohydrate-modified IgE molecules to normal mouse mast cells, nor to RBL-1 cells, as demonstrated by passive cutaneous anaphylaxis and in vitro binding tests respectively. However, traces of unglycosylated epsilon chain (mol. wt 61,000) found in tunicamycin treated cell supernatant did not bind to RBL-1 cell Fc epsilon receptors. These findings globally suggest that secretion occurs only if the tetradecasaccharide precursor of N-linked carbohydrate chains is transferred from its lipid-carrier to the polypeptide. Further, the presence of such non-processed oligosaccharides (Glc3Man9GlcNAc2) on IgE, does not seem to modify any of the biological activities of this molecule.


Assuntos
1-Desoxinojirimicina/análogos & derivados , Anticorpos Monoclonais/biossíntese , Imunoglobulina E/biossíntese , Indolizinas , Processamento de Proteína Pós-Traducional/efeitos dos fármacos , Alcaloides/farmacologia , Animais , Linhagem Celular , Glucosamina/análogos & derivados , Glucosamina/farmacologia , Glicosilação , Imunoglobulina E/metabolismo , Camundongos , Swainsonina , Tunicamicina/farmacologia
13.
J Neurol Sci ; 47(3): 379-83, 1980 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-7420113

RESUMO

A form of acute experimental autoimmune myasthenia gravis (EAMG) appears within 10 days after immunization of mice with rat acetylcholine receptor (AcChR) in complete adjuvant. This acute phase of EAMG differs from the chronic form reported earlier in the absence of detectable circulating anti-AcChR antibodies and by electrophysiologic signs of neuromuscular blockade which are not reversed by edrophonium injection. This form of acute EAMG occurs similarly in animals whose humoral response has been markedly reduced by pretreatment with cyclophosphamide. These data indicate that the pathogenesis of this acute form might differ from that of chronic EAMG and that it could involve mechanisms of cell-mediated immunity.


Assuntos
Autoanticorpos/análise , Doenças Autoimunes/imunologia , Miastenia Gravis/imunologia , Receptores Colinérgicos/imunologia , Animais , Ciclofosfamida/farmacologia , Eletrofisiologia , Feminino , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Miastenia Gravis/induzido quimicamente , Ratos
14.
JPEN J Parenter Enteral Nutr ; 24(2): 113-8, 2000.
Artigo em Inglês | MEDLINE | ID: mdl-10772192

RESUMO

BACKGROUND: Numerous studies suggest that immune function may be compromised by lipid emulsions rich in polyunsaturated fatty acids (PUFAs). In our study, we compared the effect of a new olive oil-based lipid emulsion (ClinOleic) containing a moderate level of PUFAs, with emulsions based on soybean oil (Intralipid or Ivelip), on immune functions of human cell in vitro. METHODS: Peripheral white blood cells were collected from healthy volunteers. Lymphocyte proliferation was evaluated by [3H]-thymidine incorporation after stimulation with either phytohemagglutinin (PHA) or antibodies against T-cell specific antigens. Lymphocytes subsets and T-cell activation markers (CD25 and HLA-DR) were measured by flow cytometry. The release of cytokines (interleukin [IL]-2, IL-1beta, and tumor necrosis factor-alpha [TNF-alpha]) was measured by enzyme-linked immunosorbent assay (ELISA), after lymphocytes or monocytes/macrophages stimulation with PHA or lipopolysaccharide (LPS). RESULTS: A significant dose-dependent inhibition of thymidine incorporation was observed with Intralipid and Ivelip (incorporation down to 39.9% of control, p < .001) whereas ClinOleic showed no inhibitory effect. Activation antigen expression on both CD4+ and CD8+ T-cells tended to decrease with Intralipid (CD25: -53.4% on CD4+ and -57.4% on CD8+; HLA-DR: -61.5% on CD4+ and -58.5% on CD8+) but not with ClinOleic (from -2.9% for CD25 on CD4+ to 16.7% for HLA-DR on CD4+). Intralipid decreased significantly IL-2 production (-39.0%, p < .05) whereas ClinOleic had little effect (-13.0%, NS). Intralipid and ClinOleic tended to inhibit to a similar extent the release of pro-inflammatory cytokines (TNF-alpha: -21.5% and -34.8%, IL-1beta: -45.1% and -40.3%; respectively). CONCLUSIONS: Our results suggest that an olive oil-based lipid emulsion could modulate immune response selectively, maintaining protective immunity and reducing inflammatory response. Olive oil may offer an immunologically neutral alternative to soybean oil for use in parenteral lipid emulsions.


Assuntos
Emulsões Gordurosas Intravenosas/farmacologia , Ácidos Graxos Insaturados/farmacologia , Subpopulações de Linfócitos T/efeitos dos fármacos , Subpopulações de Linfócitos T/imunologia , Membro 7 da Superfamília de Receptores de Fatores de Necrose Tumoral/efeitos dos fármacos , Adulto , Ensaio de Imunoadsorção Enzimática , Ácidos Graxos Insaturados/imunologia , Feminino , Citometria de Fluxo , Humanos , Interleucinas/metabolismo , Lipopolissacarídeos/farmacologia , Masculino , Nutrição Parenteral , Fito-Hemaglutininas/farmacologia , Subpopulações de Linfócitos T/metabolismo , Timidina/metabolismo , Membro 7 da Superfamília de Receptores de Fatores de Necrose Tumoral/imunologia , Fator de Necrose Tumoral alfa/metabolismo
15.
Clin Imaging ; 13(3): 220-4, 1989 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-2819587

RESUMO

The clinical and radiographic features of cerebral deep venous thrombosis in a 21-year-old white woman are presented. This nulliparous patient presented with relatively mild clinical symptoms and progressing mental status changes. The only known risk factor was "low-dose" oral contraceptive pills. The magnetic resonance image (MRI) showed increased signal intensity from the internal cerebral veins, vein of Galen, and straight sinus. The diagnosis was confirmed by arterial angiography.


Assuntos
Etinilestradiol/efeitos adversos , Embolia e Trombose Intracraniana/diagnóstico , Imageamento por Ressonância Magnética , Noretindrona/efeitos adversos , Adulto , Angiografia Cerebral , Veias Cerebrais/diagnóstico por imagem , Anticoncepcionais Orais Combinados/efeitos adversos , Combinação de Medicamentos , Feminino , Humanos , Embolia e Trombose Intracraniana/induzido quimicamente , Tomografia Computadorizada por Raios X
16.
Clin Nucl Med ; 13(3): 171-4, 1988 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-3289817

RESUMO

This case report presents clinical, scintigraphic, duplex sonographic, and biopsy findings in a 23-year-old female renal allograft (RAG) recipient, who had transplantation for chronic renal failure secondary to hemolytic uremic syndrome (HUS). She demonstrated acute and rapidly progressing RAG failure at 7 weeks after transplantation.


Assuntos
Síndrome Hemolítico-Urêmica/etiologia , Transplante de Rim , Adulto , Ciclosporinas/uso terapêutico , Feminino , Síndrome Hemolítico-Urêmica/diagnóstico , Síndrome Hemolítico-Urêmica/tratamento farmacológico , Síndrome Hemolítico-Urêmica/patologia , Humanos , Rim/patologia , Rim/ultraestrutura , Microscopia Eletrônica , Recidiva , Ultrassonografia
20.
J Immunol ; 126(1): 335-40, 1981 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-7451975

RESUMO

Interferons (IF) have been shown to have a complex regulatory effect on cell-mediated cytotoxicity. In this paper, we described our analysis of the protective effect of IF on human fibroblast target cells. Fibroblasts that have been preincubated with IF are not lysed by natural killer (NK) cells. This IF-induced protection is not observed in antibody-dependent cell-mediated cytotoxicity nor in complement-dependent lysis. Both types of leukocyte IF, viral and immune, and fibroblast IF protect fibroblasts from NK cell-mediated lysis. Electrophoretically purified viral type leukocyte IF also induces protection. Experiments of absorption of NK cells on target cell monolayers and analysis of cytotoxicity at the single-cell level in semisolid medium demonstrate that NK cells bind to both IF-treated and untreated fibroblasts but lyse only the latter. The cytotoxic ability of NK cells is inactivated after interaction with fibroblasts but not with IF-treated fibroblasts. Unlabeled normal fibroblasts, but not IF-treated fibroblasts, compete for the cytotoxicity mediated by NK cells on 51Cr-labeled target fibroblasts. Based on these findings, we propose a possible interpretation of the paradoxic existence of cells that can kill normal cells in the organism and still function in cell-mediated immunity to protect against virus-infected or tumor cells.


Assuntos
Citotoxicidade Imunológica , Indutores de Interferon/farmacologia , Células Matadoras Naturais/imunologia , Absorção , Animais , Ligação Competitiva , Bovinos , Relação Dose-Resposta Imunológica , Feto/citologia , Fibroblastos , Humanos , Cinética , Coelhos
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