Cutting edge: Enhancement of antibody responses through direct stimulation of B and T cells by type IIFN

Type IIFN (IFN-alpha beta) is induced rapidly by infection and plays a key role in innate antiviral defense. IFN-alpha beta also exerts stimulatory effects on the adaptive immune system and has been shown to enhance Ab and T cell responses. We have investigated the importance of B. and T cells as direct targets of IFN-alpha beta during IFN-alpha-mediated auk mentation of the Ab response against a soluble protein Ag. Strikingly, the ability of IFN-alpha to stimulate the Ab response and induce isotype switching was markedly reduced in mice in which B cells were selectively deficient for the IFN-alpha beta R. Moreover, IFN-alpha-mediated enhancement of the Ab response was also greatly impaired in mice in which T cells were selectively IFN-alpha beta R-deficient. These results indicate that IFN-alpha beta R signaling in both B and T cells plays an important role in the stimulation of Ab responses by IFN-alpha beta.