RESUMO
A Mycobacterium abscessus subspécie abscessus é um pesadelo quando envolvida em infecção pulmonar que são incuráveis, a despeito do uso de antimicrobianos com atividade in vitro, caso o tratamento não inclua a ressecção cirúrgica da área afetada. É a micobactéria patogência de crescimento rápido mais frequentemente isolada de culturas de sítios pulmonares. Há um número reduzido de opções terapêuticas para o tratamento dessas infecções, e é ainda mais reduzido o número de antimicrobianos que atingem concentrações terapêuticas no compartimento intracelular, em particular no fagossomo. O número limitado de antimicrobianos disponíveis para tratamento apontam a necessidade de determinação do perfil de susceptibilidade frente a antimicrobianos isolados e em combinação, nos compartimentos intra e extracelular. Os objetivos deste estudo foram avaliar: a sensibilidade de M. abscessus estruturadas em biofilmes e presentes no interior dos macrófagos; a ocorrência de sinergismo quando da associação entre fármacos, inibidores de betalactamase e o anti-inflamatório. As combinações entre os antimicrobianos foram apenas indiferente quanto ao FIC e a atividade dos fármacos em biofilme e em macrófagos é bacteriostático
Mycobacterium abscessus subspecies abscessus is a nightmare when involved in lung infection that is incurable, despite the use of antibiotics with in vitro activity, if the treatment does not include surgical resection of the affected area. It is a MCR - rapidly growing mycobacteria pathogenic most frequently isolated from cultures of lung sites. There are a small number of therapeutic options for the treatment of such infections is further reduced and the number of drugs that reach therapeutic concentrations in the intracellular compartment, particularly in the phagosome. The limited number of antimicrobials available for treatment indicate the need for determining the susceptibility profile against antimicrobials alone and in combination, in the intra and extracellular compartments. The objectives of this study were sensitivity of MCR structured biofilms and present in macrophages, the occurrence of synergism when the association between drugs, beta-lactamase inhibitors and anti-inflammatory. Combinations of antimicrobials were just indifferent and the activity of drugs on biofilms and macrophages was bacteriostatic
Assuntos
Fagossomos/fisiologia , Biofilmes/classificação , Anti-Infecciosos/análise , Infecções por Mycobacterium/prevenção & controle , Pneumopatias/complicações , Macrófagos/classificaçãoRESUMO
At the phagosome level, Mycobacterium spp. alters activation and recruitment of several "Ras gene from rat brain" proteins, commonly known as Rab. Mycobacterial phagosomes have a greater and sustained expression of Rab5, Rab11, Rab14 and Rab22a, and lowered or no expression of Rab7, Rab9 and Rab6. This correlates with increased fusion of the phagosomes with early and recycling endosomes acquiring some features of early phagosomes, allowing the bacteria to gain access to nutrients and preventing the activation of anti-mycobacterial mechanisms. The expression of constitutively active mutants of Rab from the early stage endosomes prevents the maturation of phagosomes containing latex beads or heat-inactivated mycobacteria. Silencing of these mutants by interference RNA or dominant negative forms induces the maturation of mycobacterial phagosomes. The mechanisms have not been established by which mycobacteria alter the expression of these GTPases and thereby shift the phagolysosomal maturation. The problem can be explained by alterations in the recruitment of proteins that interact with Rab, such as phosphoinositide 3-kinases and early endosomal antigen 1. Identifying the mechanisms used by Mycobacterium spp. to disrupt the cycle of Rab activation will be essential to understand the pathophysiology of mycobacterial infections and usefully to potential drug targets.
Assuntos
Infecções por Mycobacterium/metabolismo , Proteínas rab de Ligação ao GTP/fisiologia , Animais , Humanos , Fagossomos/fisiologiaRESUMO
Autophagy is an early cellular event during acute pancreatitis, a disease defined as pancreas self-digestion. The Vacuole Membrane Protein 1 (VMP1) is a trans-membrane protein highly activated in acinar cells early during pancreatitis-induced autophagy and it remains in the autophagosomal membrane. We have shown that VMP1 expression is able to trigger autophagy in mammalian cells, even under nutrient-replete conditions. VMP1 is induced by autophagy stimuli and its expression is required for autophagosome development. VMP1 interacts with Beclin 1 through its hydrophilic C-terminal region, which we named Atg domain, as it is essential for autophagy. Remarkably, VMP1 pancreas-specific transgenic expression in mice promotes autophagosome formation. Most of the autophagy-related proteins were described in yeast or have a yeast homologue. VMP1 does not have any known homologue in yeast but its expression is required to start the autophagic process in mammalian cells. These findings support the hypothesis that mammalian cells may regulate autophagy in a different way. We propose that VMP1 is a novel autophagy related trans-membrane protein, which may lead the way in the search for alternative mechanisms of autophagosome formation.
Assuntos
Autofagia/fisiologia , Proteínas de Membrana/fisiologia , Doença Aguda , Animais , Proteínas Reguladoras de Apoptose/fisiologia , Proteína Beclina-1 , Humanos , Camundongos , Pancreatite/metabolismo , Fagossomos/fisiologia , Ligação Proteica , Proteínas/fisiologia , Transdução de SinaisRESUMO
Coxiella burnetii is a Gram-negative obligate intracellular bacterium that infects a wide range of hosts including humans, causing Q fever, a disease characterized by high fever and flu-like symptoms. After its internalization the Coxiella-containing phagosomes interact with intracellular compartments and generate a large replicative vacuole that displays certain characteristics of a phagolysosome. We have shown that this bacterially-customized replicative vacuole also has the hallmarks of an autophagosomal compartment. Furthermore, in a recent publication we have reported that induction of autophagy is beneficial for the replication and survival of Coxiella. Different morphological forms of this bacterium have been described during its developmental cycle. Here we present additional data and discuss a model indicating that induction of autophagy favors the differentiation of the Coxiella small cell variants to the metabolically active large cells variants. We postulate that nutrient acquisition, likely by fusion with the nutrient-rich autophagic vacuoles, triggers the development of the large cell variants which actively multiply in the host cell.
Assuntos
Autofagia , Coxiella burnetii/fisiologia , Fagocitose , Fagossomos/fisiologia , Coxiella burnetii/ultraestrutura , Meios de Cultura Livres de Soro , Células HeLa , Humanos , Lisossomos/fisiologia , Fusão de Membrana , Microscopia Eletrônica de Transmissão , Vacúolos/fisiologiaRESUMO
Toxoplasma gondii invades and proliferates in human umbilical vein endothelial cells (HUVEC) where it resides in a parasitophorous vacuole (PV) preventing lysosomal fusion. To study the intracellular outcome of PV containing tachyzoites of T. gondii during interaction with IFN-gamma-activated HUVEC, a quantitative analysis of the T. gondii infection and multiplication was assayed. The quantification of PVs' fusion with lysosomes, ultrastructural examination of phagosome-lysosome fusion, and the localization of NAD(P)H-oxidase activity were also investigated. HUVEC activated with IFN-gamma inhibited T. gondii infection and multiplication by 67.5% and 91.0%, respectively. After 4 hr of infection, 10.2% of IFN-gamma-activated HUVEC exhibited phagosome-lysosome fusion assayed by fluorescence microscopy, which was also observed at the ultrastructural level. Furthermore, the enzyme NAD(P)H-oxidase present at the plasma membrane of activated HUVEC was internalized together with the parasite in 38.0% of the cells. In addition, colocalization of colloidal gold particles and reaction product of NAD(P)H-oxidase in the PV of some activated HUVEC was observed. These results suggest that NAD(P)H-oxidase may participate in a mechanism by which IFN-gamma-activated HUVEC inhibit T. gondii multiplication.
Assuntos
Células Endoteliais/parasitologia , NADPH Oxidases/metabolismo , Toxoplasma/enzimologia , Vacúolos/enzimologia , Vacúolos/parasitologia , Animais , Corantes , Células Endoteliais/efeitos dos fármacos , Células Endoteliais/ultraestrutura , Feminino , Coloide de Ouro , Histocitoquímica , Humanos , Interferon gama/farmacologia , Lisossomos/fisiologia , Camundongos , Microscopia Eletrônica de Transmissão , Fagossomos/fisiologia , Toxoplasma/ultraestrutura , Veias Umbilicais , Vacúolos/ultraestruturaRESUMO
The virulence of different isolates of Mycobacterium has been associated with two morphologically distinguishable colonial variants: opaque (SmOp) and transparent (SmTr). In this report we used an in vitro assay to compare macrophage (Mphi) responses to SmOp and SmTr Mycobacterium fortuitum variants, taking advantage of the fact that these variants were derived from the same isolate. Cells preactivated or not with gamma interferon (IFN-gamma) were infected with SmOp or SmTr M. fortuitum. We showed that SmOp and SmTr induced different levels of nitric oxide (NO) production by IFN-gamma-stimulated Mphi. Indeed, the amount of IFN-gamma-induced NO production by J774 cells was 4.8 to 9.0 times higher by SmOp (23.1 to 37.7 micro M) compared to SmTr infection (3.9 to 4.8 micro M) (P = 0.0332), indicating that virulent SmTr bacilli restricted NO production. In addition, IFN-gamma-induced NO production by Mphi was higher when correlated with reduction of only avirulent SmOp bacillus viability. SNAP (S-nitroso-N-acetyl-DL-penicillamine)-induced NO production did not modify SmTr viability, indicating its resistance to nitrogen radicals. Electron microscopy studies were performed to evaluate the capacity of phagosomes to fuse with lysosomes labeled with bovine serum albumin-colloidal gold particles. By 24 h postinfection, 69% more phagosome-containing SmOp variant had fused with lysosomes compared to the SmTr-induced phagosomes. In conclusion, these data indicate that virulent SmTr bacilli may escape host defense by restricting IFN-gamma-induced NO production, resisting nitrogen toxic radicals, and limiting phagosome fusion with lysosomes.
Assuntos
Interferon gama/farmacologia , Lisossomos/fisiologia , Macrófagos/microbiologia , Macrófagos/fisiologia , Mycobacterium fortuitum/patogenicidade , Óxido Nítrico/biossíntese , Fagossomos/fisiologia , Animais , Linhagem Celular , Variação Genética , Lisossomos/microbiologia , Lisossomos/ultraestrutura , Ativação de Macrófagos/efeitos dos fármacos , Macrófagos/ultraestrutura , Fusão de Membrana , Camundongos , Microscopia Eletrônica , Mycobacterium fortuitum/isolamento & purificação , Mycobacterium fortuitum/fisiologia , Fagossomos/microbiologia , Fagossomos/ultraestrutura , Proteínas Recombinantes , Virulência/genéticaRESUMO
Light and electron microscopy were used to analyse the process of interaction of Streptococcus agalactiae (serotypes Ia, III, and V) with resident and activated mouse peritoneal macrophages. Transmission electron microscopy showed that adherence of the S. agalactiae serotype Ia, but not III and V serotypes, to the surface of activated macrophages triggers the respiratory oxidative burst as revealed by the presence of reduced nicotinamide adenine dinucleotide (phosphate) [NAD(P)H]-oxidase in the phagocytic vacuoles. Fusion of macrophage lysosomes with bacteria-containing phagocytic vacuoles was observed in macrophages treated with Lucifer yellow as well as by localization of acid phosphatase for all serotypes.
Assuntos
Macrófagos Peritoneais/citologia , Macrófagos Peritoneais/microbiologia , Streptococcus agalactiae/citologia , Streptococcus agalactiae/fisiologia , Fosfatase Ácida/metabolismo , Animais , Células Cultivadas , Histocitoquímica , Isoquinolinas , Lisossomos/microbiologia , Lisossomos/fisiologia , Lisossomos/ultraestrutura , Ativação de Macrófagos , Macrófagos Peritoneais/ultraestrutura , Camundongos , Microscopia Confocal , Microscopia Eletrônica , NADPH Oxidases/metabolismo , Fagossomos/microbiologia , Fagossomos/fisiologia , Fagossomos/ultraestrutura , Explosão Respiratória , Streptococcus agalactiae/classificação , Streptococcus agalactiae/ultraestruturaRESUMO
P. aeruginosa is selectively internalized by human endothelial cells but is not efficiently killed in the intracellular (IC) compartment. To investigate whether IC survival is associated with failure in bacteria-containing endosome-lysosome (E-L) fusion, endothelial cells were exposed to albumin-colloidal gold complex and to bacterial suspension and submitted to transmission electron microscopy (TEM). Gold granules were detected in P. aeruginosa-containing vacuoles, indicating that E-L fusion had occurred. Bacteria were also seen apparently free in the cell cytoplasm, suggesting disruption of endosome membranes. To ascertain whether phospholipase C (PLC) could account for vacuolar lysis, PLC producing PAO1 and PAK strains were compared with a PLC deficient mutant (PLCN) in their IC survival. All three strains were equally uptaken by the endothelial cells, as determined by the gentamicin exclusion assay. After 3 h of infection, the IC concentration of PAK and PAO1 increased significantly while the concentration of the mutant decreased to 56.8 +/- 18.2% of the viable counts at 1 h of infection. After 5 h, the IC concentration of P. aeruginosa corresponded to 83.1 +/- 34.6%, 109 +/- 22.6% and 26.2 +/- 14.7% of the viable counts detected at 1 h, for PAK, PAO1 and the mutant, respectively. By TEM, while most PAO1-containing vacuoles presented partially lysed membranes, in cells infected with the PLCN mutant bacteria were most often observed in vacuoles with intact membranes. These observations suggest that the IC survival of P. aeruginosa results from a competition between the microbicidal activity of endothelial cells following E-L fusion and the capacity of bacteria to escape from endosomes.
Assuntos
Endossomos/ultraestrutura , Endotélio Vascular/microbiologia , Endotélio Vascular/ultraestrutura , Fagossomos/ultraestrutura , Pseudomonas aeruginosa/fisiologia , Sobrevivência Celular , Células Cultivadas , Cloroquina/farmacologia , Citoplasma/microbiologia , Citoplasma/ultraestrutura , Endossomos/fisiologia , Endotélio Vascular/fisiologia , Humanos , Membranas Intracelulares/fisiologia , Membranas Intracelulares/ultraestrutura , Fusão de Membrana , Microscopia Eletrônica , Fagossomos/fisiologia , Pseudomonas aeruginosa/efeitos dos fármacos , Pseudomonas aeruginosa/ultraestrutura , Fosfolipases Tipo C/metabolismo , Vacúolos/microbiologia , Vacúolos/fisiologia , Vacúolos/ultraestruturaRESUMO
BACKGROUND: Previously we demonstrated that monocyte phagolysosomal fusion is impaired in chronic HIV infection in adult patients. METHODS: We studied the phagolysosomal fusion of peripheral blood monocytes from 45 children vertically infected with HIV, 38 noninfected infants born to HIV-positive mothers and 14 children born to HIV-seronegative women, by a cytomorphologic method in which acridine orange is used as a fusion marker. RESULTS: The mean percentages of phagolysosomal fusion +/-SD were 42 +/- 16.1 for HIV-positive children, 55.3 +/- 15.5 for HIV-negative infants born to HIV-infected mothers and 58.2 +/- 12.7 for normal controls. Monocyte phagolysosomal fusion of HIV-infected children was significantly decreased in comparison to noninfected and normal infants (P < 0.001), while there was no difference between the two latter groups. Phagolysosomal fusion impairment in HIV-infected infants inversely correlated with age (r = -0.4527; P < 0.002) and directly correlated with CD4+ T cell counts (r = 0.393; P = 0.03). Moreover, phagolysosomal fusion strongly correlated with clinical manifestations; this function was significantly impaired in moderately and severely symptomatic HIV-infected children with respect to those who remained asymptomatic or mildly symptomatic (P < 0.05). CONCLUSIONS: Our results suggest that monocyte function in HIV-infected children progressively deteriorates, closely related to the severity of the clinical symptoms.
Assuntos
Infecções por HIV/sangue , Transmissão Vertical de Doenças Infecciosas , Fagossomos/fisiologia , Contagem de Linfócito CD4 , Criança , Pré-Escolar , Progressão da Doença , Infecções por HIV/congênito , Infecções por HIV/fisiopatologia , Infecções por HIV/transmissão , Humanos , Lactente , Recém-Nascido , FagocitoseRESUMO
Studies on fixed preparations have shown that vacuoles containing zymosan (Z) particles internalized by infected macrophages can selectively fuse with the large parasitophorous vacuoles (PVs) that shelter Leishmania amazonensis. To examine the kinetics of vacuolar fusion in individual cells, particles were followed by time-lapse cinemicrography from their uptake to their entry in a PV. Newly formed Z-containing vacuoles moved centripetally and, if they contacted a PV, the two vacuoles remained closely apposed for variable, often extended, periods of time before they eventually fused. Transmission electron microscopy confirmed that the cytoplasm separating the partner vacuoles could be reduced to a very thin layer. Initiation of fusion was indicated by reduced refractility of the boundary between Z vacuoles and target PVs. Within a few minutes the PV enlarged and encompassed the Z particles, which remained immobile throughout. The interval between phagocytosis and fusion, 50 +/- 7.4 min (N = 17; range, 4 to 108 min), suggests that most but not all Z vacuoles underwent significant maturation by the time of fusion. Some particles were transferred singly, others entered PVs in groups of 2 or more, and additional clustered transfers to the same vacuole were also observed. These observations provide a baseline for studies of the biochemical mechanisms and the pharmacological control of the fusion of Leishmania PVs, and for the comparison of the fusion behavior of the PVs with that of other phagocytically derived vacuoles.
Assuntos
Leishmania mexicana/fisiologia , Fagossomos/fisiologia , Vacúolos/fisiologia , Zimosan , AnimaisAssuntos
Biologia Molecular , Complexo Mycobacterium avium , Complexo Mycobacterium avium/citologia , Complexo Mycobacterium avium/imunologia , Complexo Mycobacterium avium/patogenicidade , Cápsulas Bacterianas/fisiologia , Cápsulas Bacterianas/química , Fagossomos/fisiologia , Fagossomos/microbiologia , Fagócitos/fisiologia , Fagócitos/imunologia , Fagócitos/microbiologia , Hanseníase/imunologia , Hanseníase/metabolismo , Hanseníase/microbiologia , Mycobacterium bovis , Mycobacterium bovis/citologia , Mycobacterium bovis/imunologia , Mycobacterium bovis/patogenicidade , Mycobacterium tuberculosis , Mycobacterium tuberculosis/citologia , Mycobacterium tuberculosis/imunologia , Mycobacterium tuberculosis/patogenicidade , Oxirredução , Peróxido de Hidrogênio/farmacologia , Tuberculose Bovina/imunologia , Tuberculose Bovina/metabolismo , Tuberculose Bovina/microbiologia , Tuberculose/imunologia , Tuberculose/metabolismo , Tuberculose/microbiologia , VirulênciaRESUMO
We evaluated phagolysosomal fusion in peripheral blood monocytes from 20 HIV-infected individuals and 40 normal controls, using a fluorescence assay with acridine orange as marker. The percentages of phagolysosomal fusion of monocytes from HIV-infected subjects, after 30 and 60 min of yeast ingestion, (mean +/- standard deviation) 57.2 +/- 17 and 63.2 +/- 18.6, respectively, when compared to normal controls (72.4 +/- 7.8 and 77 +/- 8.1), did not differ significantly. However, there was a direct linear association between the percentages of phagolysosomal fusion and CD4+ lymphocytes (P < 0.001) or CD4/CD8 T-cell ratio (P < 0.01). These results suggest that phagolysosomal dysfunction becomes evident at late stages of HIV infection and progresses as CD4+.T-lymphocyte count and CD4/CD8 T-cell ratio decrease. On the other hand, recombinant gp120 inhibited significantly normal phagolysosomal fusion at concentrations ranging between 1 and 1000 ng/ml. Taking together the results obtained, we can conclude that gp120 could be responsible for monocyte phagolysosomal dysfunction observed in HIV infected patients.
Assuntos
Infecções por HIV/sangue , HIV-1 , Lisossomos/fisiologia , Monócitos/fisiologia , Fagossomos/fisiologia , Adulto , Relação CD4-CD8 , Fusão Celular , Feminino , Proteína gp120 do Envelope de HIV/farmacologia , Infecções por HIV/patologia , Humanos , Lisossomos/patologia , Masculino , Pessoa de Meia-Idade , Fagocitose , Fagossomos/patologia , Proteínas Recombinantes/farmacologiaRESUMO
Light and electron microscopy were used to analyse the process of interaction of normal and antibody-coated Tritrichomonas foetus with resident and activated mouse peritoneal macrophages. Activated macrophages ingest more parasites than do resident macrophages. Previous incubation of the parasites in the presence of sub-agglutinating concentrations of a polyclonal anti-T. foetus antibody significantly increased their ingestion by the macrophages. Adherence of the parasites to the surface of activated macrophages triggers the respiratory oxidative burst as revealed by reduction of nitroblue tetrazolium. This process was more evident in antibody-coated parasites. Transmission electron microscopy showed the presence of reduced nicotinamide adenine dinucleotide (phosphate) [NAD(P)H]-oxidase in the portions of the macrophage plasma membrane that were in contact with the parasites as well as in the phagocytic vacuoles. Fusion of macrophage lysosomes with parasite-containing phagocytic vacuoles was observed in macrophages labeled with Lucifer yellow and gold-labeled peroxidase as well as by localisation of acid phosphatase.
Assuntos
Macrófagos/parasitologia , Tritrichomonas foetus/fisiologia , Animais , Células Cultivadas , Histocitoquímica , Cinética , Lisossomos/fisiologia , Lisossomos/ultraestrutura , Macrófagos/ultraestrutura , Camundongos , Microscopia Eletrônica , Oxirredução , Fagossomos/fisiologia , Fagossomos/ultraestrutura , Explosão Respiratória , Tritrichomonas foetus/ultraestruturaRESUMO
Phagosomes are membrane-bound vesicles, formed by the receptor-mediated internalization of particulate ligands, which exchange soluble and membrane proteins with other endocytic compartments as a part of their maturation process. This exchange of material is undoubtedly mediated by fusion of phagosomes with other membrane-bound compartments of the endocytic pathway. By using a particulate probe (fixed Staphylococcus aureus coated with mouse anti-dinitrophenol monoclonal antibody) localized in phagosomes and a soluble probe (dinitrophenol-derivitized beta-glucuronidase) internalized by receptor-mediated endocytosis, we have studied phagosome-endosome and phagosome-lysosome fusion in intact cells and in a cell-free system. Vesicle fusion was assessed by measuring beta-glucuronidase activity associated with S. aureus particles after lysis of the membranes. In intact macrophages, newly formed phagosomes fused with early endosomes and with lysosomes. Fusion with lysosomes was observed to commence after a short lag period of about 5 min. In broken-cell preparations, phagosomes were able to fuse with early endosomes. It was not possible to reconstitute phagosome-lysosome fusion in vitro. In vitro phagosome-endosome fusion required energy and cytosolic- and membrane-associated proteins. A nonhydrolyzable analog of GTP stimulated fusion at low cytosol concentrations and inhibited fusion at high cytosol concentrations. These observations indicate that the mechanisms mediating phagosome-endosome fusion are similar to those described for endosome-endosome fusion. Our results suggest that exchange of material with endosomes is an important step in the process of phagosome maturation.
Assuntos
Fagossomos/fisiologia , Staphylococcus aureus/metabolismo , Fusão Celular , Sistema Livre de Células , Endocitose , Microscopia EletrônicaRESUMO
The participation of cell surface anionic sites on the interaction between tachyzoites of Toxoplasma gondii and macrophages and the process of phagosome-lysosome fusion were analyzed using cationized ferritin as a marker of cell surface anionic sites and albumin-colloidal gold as a marker for secondary lysosomes. Incubation of either the macrophages or the parasites with cationized ferritin before the interaction increased the ingestion of parasites by macrophages. Anionic sites of the macrophage's surface, labeled with cationized ferritin before the interaction, were internalized together with untreated parasites. However, after interaction with glutaraldehyde-fixed or specific antibody-coated parasites, the cationized ferritin particles were observed in endocytic vacuoles which did not contain parasites. Macrophages previously labeled with albumin-gold at 37 degrees C, were incubated in the presence of cationized ferritin at 4 degrees C and then incubated with untreated or specific antibody-coated parasites. After interaction with opsonized parasites, the colloidal gold particles were observed in the parasitophorous vacuoles while the cationized ferritin particles were observed in cytoplasmic vesicles. However, when the interaction was carried out with untreated parasites, the parasitophorous vacuoles exhibited ferritin particles while the colloidal gold particles were observed in cytoplasmic vesicles. These observations, in association with studies previously reported, suggest that the state of the parasite surface determines the mechanism of parasite entry into the macrophage, the composition of the membrane lining the parasitophorous vacuole and the ability of lysosomes to fuse with the vacuoles.
Assuntos
Ânions/metabolismo , Endocitose/fisiologia , Lisossomos/fisiologia , Macrófagos/fisiologia , Fagossomos/fisiologia , Toxoplasma/imunologia , Albuminas , Animais , Membrana Celular/metabolismo , Ferritinas/farmacologia , Ouro , Ligantes , Macrófagos/metabolismo , Fusão de Membrana/fisiologia , Camundongos , Microscopia EletrônicaRESUMO
A new procedure for labeling of secondary lysosomes and to determine, by transmission electron microscopy, their fusion with phagosomes was developed. It is based on the use of albumin adsorbed to colloidal gold particles as a probe and tested using macrophages previously labeled with albumin-gold and then incubated in the presence of epimastigote forms of Trypanosoma cruzi.