Presentation of Toxoplasma gondii antigens via the endogenous major histocompatibility complex class I pathway in nonprofessional and professional antigen-presenting cells.
Infect Immun
; 75(11): 5200-9, 2007 Nov.
Article
en En
| MEDLINE
| ID: mdl-17846116
ABSTRACT
Challenge with the intracellular protozoan parasite Toxoplasma gondii induces a potent CD8+ T-cell response that is required for resistance to infection, but many questions remain about the factors that regulate the presentation of major histocompatibility complex class I (MHC-I)-restricted parasite antigens and about the role of professional and nonprofessional accessory cells. In order to address these issues, transgenic parasites expressing ovalbumin (OVA), reagents that track OVA/MHC-I presentation, and OVA-specific CD8+ T cells were exploited to compare the abilities of different infected cell types to stimulate CD8+ T cells and to define the factors that contribute to antigen processing. These studies reveal that a variety of infected cell types, including hematopoietic and nonhematopoietic cells, are capable of activating an OVA-specific CD8+ T-cell hybridoma, and that this phenomenon is dependent on the transporter associated with antigen processing and requires live T. gondii. Several experimental approaches indicate that T-cell activation is a consequence of direct presentation by infected host cells rather than cross-presentation. Surprisingly, nonprofessional antigen-presenting cells (APCs) were at least as efficient as dendritic cells at activating this MHC-I-restricted response. Studies to assess whether these cells are involved in initiation of the CD8+ T-cell response to T. gondii in vivo show that chimeric mice expressing MHC-I only in nonhematopoietic compartments are able to activate OVA-specific CD8+ T cells upon challenge. These findings associate nonprofessional APCs with the initial activation of CD8+ T cells during toxoplasmosis.
Texto completo:
1
Base de datos:
MEDLINE
Asunto principal:
Toxoplasma
/
Antígenos de Histocompatibilidad Clase I
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Toxoplasmosis
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Linfocitos T CD8-positivos
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Células Presentadoras de Antígenos
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Antígenos de Protozoos
Límite:
Animals
Idioma:
En
Revista:
Infect Immun
Año:
2007
Tipo del documento:
Article
País de afiliación:
Estados Unidos