Thus, plexinA1 (plexA1) and NP-1 were implicated in DC migration through endothelial layers and lymphatic entry 29, yet also in T-cell activation by murine or

human DC 30–32, though neither their co-segregation at the IS nor their ligands there clearly identified. In contrast, the plexA1/NP-1 complex relays repulsive signals when exposed to soluble SEMA3A thereby causing loss of thymocyte adhesion, impairing actin cytoskeletal reorganization and activation of essential components of TCR signalling, or controlling Fas-mediated apoptosis 33–37. Apparently, timely regulated IS recruitment and the respective interaction molecule essentially determine the ability of plexA1/NP-1 to promote or terminate T-cell activation. In line with this hypothesis, repulsive SEMA3A is produced only late in DC/T-cell co-cultures 34. The role of plexA1/NP-1 and their ligands in viral immunomodulation Selleck Doxorubicin has not yet been addressed. Based on the hypothesis that signalling to conjugating T cells might contribute to MV interference with IS stability and function, we addressed the role of plexA1/NP-1 and their ligand SEMA3A in this system. We found that levels of plexA1/NP-1 on MV-exposed T cells or MV-infected DC did not differ from those measured on controls. In T cells, however, contact to the viral gps abrogated translocation of both plexA1 and NP-1 towards stimulatory interfaces as required

for their ability to enhance IS efficiency. As a second STA-9090 ic50 level of IS interference, MV-DC released high Thalidomide levels of repulsive SEMA3A early after infection and this accounted for loss of filamentous actin and actin-based protrusions of T cells, altogether indicating that MV affects plexA1/NP-1 signalling in the IS. PlexA1/NP-1 supports IS stability and function, both of which are impaired if these involve MV-infected DC (MV-DC), or T cells pre-exposed to the MV gp complex. To analyze the role of plexA1/NP-1 in destabilization of the MV-DC/T-cell IS, we first

analyzed whether MV affected surface expression of these molecules within the experimental conditions used throughout our study. These involved MV-infected DC (to evaluate effects of direct infection as occurring in vivo 6) and T cells exposed to UV-inactivated MV to mimic T-cell surface contact-dependent signalling elicited by the viral gp complex (displayed by MV-infected DC) in the presence of fusion inhibitory peptide (to avoid MV uptake). In line with the published data, both plexA1 and NP-1 were expressed to very low levels on freshly isolated human primary T cells, and this was not altered upon UV-MV exposure (or mock exposure; both applied for 2 h) (Fig. 1A). In permeabilized T cells, especially plexA1 was efficiently detected indicating it mainly resides in intracellular compartments (not shown here, and Fig. 2C).