|
|
|
|
A more recent version of this article appeared on February 1, 2008
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Submitted on July 10, 2007
Revised on November 16, 2007
Accepted on November 28, 2007
*Servicio de Inmunología, Hospital de la Princesa, Universidad Autónoma de Madrid, 28006 Madrid, Spain;
Departamento de Biología Vascular e Inflamación, Centro Nacional de Investigaciones Cardiovasculares (CNIC), 28029 Madrid, Spain;
Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Cantoblanco, Madrid, Spain
Monitoring Editor: J. Silvio Gutkind
The array of phagocytic receptors expressed by macrophages make them very efficient at pathogen clearance and the phagocytic process links innate with adaptive immunity. Primary macrophages modulate antigen cross-presentation and T-cell activation. We assessed ex vivo the putative role of different phagocytic receptors in immune synapse formation with CD8 naïve T-cells from OT-I transgenic mice, and compared this with the administration of antigen as a soluble peptide. Macrophages that have phagocytosed antigen induce T-cell MTOC and F-actin cytoskeleton relocalization to the contact site, as well as the recruitment of proximal TCR signals such as activated Vav1 and PKC [theta]. At the same doses of loaded antigen (1 µM), phagocytic macrophages were more efficient than peptide-antigen loaded macrophages at forming productive immune synapses with T-cells, as indicated by active T-cell TCR/CD3 conformation, LAT phosphorylation, IL-2 production, and T-cell proliferation. Similar T-cell proliferation efficiency was obtained when low doses of soluble peptide (3–30 nM) were loaded on macrophages. These results suggest that the pathway used for antigen uptake may modulate the antigen density presented on MHC-I resulting in different signals induced in naïve CD8 T-cells, leading either to CD8 T-cell activation or anergy.