RESUMO
Previous work in this laboratory has demonstrated that ovalbumin coupled to palmitoyl residues (palmitoyl-Ova) does not induce oral tolerance. The present study sought to determine whether this coupling affects digestion, absorption and transfer of antigen. Ova and palmitoyl-Ova were shown to be digested differently in vitro by proteolytic enzymes and presented different tissue distribution kinetics after being labelled with (99m)technetium and orally administered to animals. Palmitoyl-Ova remained longer in the stomach, while native Ova was quickly transferred to the gut and other organs. After 3 h, higher levels of palmitoyl-Ova were found in the blood, Peyer's patches, mesenteric lymph nodes, liver and, especially, the spleen, which appears to be essential for immunization with palmitoyl-Ova. In fact, splenectomized mice treated orally with palmitoyl-Ova became tolerant, while tolerance to Ova was not affected. Thus, palmitoyl coupling was demonstrated to affect antigen digestion, absorption and transport. This is the first time that the spleen has been shown to be required for oral immunization with palmitoyl-Ova.
Assuntos
Ovalbumina/imunologia , Ovalbumina/farmacocinética , Ácidos Palmíticos/imunologia , Baço/imunologia , Administração Oral , Animais , Antígenos/análise , Antígenos/imunologia , Digestão , Feminino , Trato Gastrointestinal/enzimologia , Masculino , Camundongos , Camundongos Endogâmicos , Ovalbumina/administração & dosagem , Ácidos Palmíticos/administração & dosagem , Distribuição TecidualRESUMO
The effects of chronic unpredictable stress on airway leukocyte infiltration and plasma extravasation in female rats have been investigated. The chronic stress lasted for 14 days and consisted of transitory and variable changes in the living conditions of the animals. Concomitant to the stress procedure, the animals were sensitized (Day 0) and challenged with ovalbumin (OVA; 200 microg) at Day 14. Bronchoalveolar lavage (BAL) was performed 48 h after intratracheal challenge with OVA (0.4 ml of a 0.25% solution). The increase in plasma extravasation was assessed by the rat paw oedema induced by OVA (0.1 mg/paw) or the mast cell degranulator compound 48/80 (5 microg/paw). A significant increase (P < .05) in the total leukocyte influxes into the airways was observed in the stressed (sensitized) group compared to nonstressed (sensitized) animals, and this was associated with a marked recruitment of eosinophils and mononuclear cells in the BAL fluid. In OVA-sensitized rats, intraplantar injection of OVA induced a marked paw oedema that was significantly higher in stressed compared to nonstressed groups. In contrast to OVA, the compound 48/80 (5 microg/paw)-induced oedema did not significantly differ between nonstressed and stressed groups. Our results indicate that chronic unpredictable stress exacerbates the vascular and cellular inflammatory responses.
Assuntos
Hipersensibilidade/complicações , Hipersensibilidade/fisiopatologia , Estresse Fisiológico/complicações , Animais , Líquido da Lavagem Broncoalveolar/citologia , Feminino , Hipersensibilidade/sangue , Hipersensibilidade/patologia , Contagem de Leucócitos , Ovalbumina/sangue , Ovalbumina/farmacocinética , Ratos , Ratos Wistar , p-Metoxi-N-metilfenetilamina/sangue , p-Metoxi-N-metilfenetilamina/farmacocinéticaRESUMO
We describe in this report the characterization and kinetics of MHC class I-restricted presentation of a soluble antigen delivered by liposomes. pH-sensitive liposomes delivered ovalbumin (OVA) to the class I pathway more efficiently than pH-insensitive liposomes; the latter showed competence in the class I-restricted sensitization only when a large antigen loading dose was used. Such sensitization of EL4 cells resulted from substantial delivery of the ingested liposomal OVA to the cytosolic compartment as revealed with immunogold electron microscopy. Most of the ingested liposomal OVA were rapidly catabolized and released into the extracellular medium. The residual processed antigen took about 2 h to egress to the cell surface for recognition by CTL. The liposome-mediated antigen presentation exhibited a transient kinetics which was manipulable with antigen dose. Brefeldin A, an ER-to-Golgi transport inhibitor, strongly inhibited such presentation. The antigens displayed on the cell surface could also be removed by a brief acid wash of the cells and subsequently reappeared on the surface if an intracellular pool of antigen existed at the time of acid wash.