Measles virus exploits dendritic cells to suppress CD4+ T-cell proliferation via expression of surface viral glycoproteins independently of T-cell trans-infection

Dendritic cells (DC) have been proposed to play a pivotal role in transient immune suppression induced by measles virus (MV) infection. In the present study, we show that DC-induced suppression of T-cell proliferation was not mediated by IL-10 or IFNalpha/beta, which are released following infection of DC, but required cell contacts between MV-infected DC and T cells. Human sera containing neutralizing anti-MV antibodies, as well as anti-MV hemagglutinin (HA) or fusion protein (F) mAbs, were found (i) to reverse suppression and (ii) to restore DC allostimulatory capacity. Interestingly, DC-induced T-cell suppression was associated with both phenotypic and functional DC maturation, as demonstrated by IL-12 production and chemotaxis to MIP-3beta. These data suggest that MV infection turns on the maturation program of DC allowing migration to draining lymph nodes, where potent T-cell immune suppression might be achieved via cell surface expression of HA and F glycoproteins, independently of T cell trans-infection.