Natural interferon α/β-producing cells (IPCs) play a critical role in linking innate and adaptive immunity. When stimulated by viruses, IPCs produce large amounts of antiviral interferon (IFN)-α/β and differentiate into dendritic cells (DCs). These virus-activated IPCs secrete IFN-α/β and tumor necrosis factor (TNF)-α, which act as autocrine survival and differentiation factors for IPCs and DCs, respectively. The DCs generated from IPCs stimulate naive CD4+ T cells to produce IFN-γ and IL-10, unlike IL-3-induced DCs, which promote T helper type 2 (Th2) cytokines such as IL-4, IL-5, and IL-10. Thus, IPCs perform two key functions in antiviral immunity: directly inhibiting viral replication by producing IFN-α/β and subsequently triggering adaptive T cell-mediated immunity by differentiating into DCs. IPCs serve as a critical bridge between innate and adaptive immunity. The study shows that viruses can directly induce IPCs to differentiate into DCs without exogenous cytokines. This process is essential for initiating and directing adaptive immune responses. IPCs can also differentiate into Th2-inducing DCs in response to IL-3, suggesting their versatility in immune responses. The findings highlight the importance of IPCs in both innate and adaptive immunity, and their potential as therapeutic targets for infectious diseases, cancers, and allergic conditions.Natural interferon α/β-producing cells (IPCs) play a critical role in linking innate and adaptive immunity. When stimulated by viruses, IPCs produce large amounts of antiviral interferon (IFN)-α/β and differentiate into dendritic cells (DCs). These virus-activated IPCs secrete IFN-α/β and tumor necrosis factor (TNF)-α, which act as autocrine survival and differentiation factors for IPCs and DCs, respectively. The DCs generated from IPCs stimulate naive CD4+ T cells to produce IFN-γ and IL-10, unlike IL-3-induced DCs, which promote T helper type 2 (Th2) cytokines such as IL-4, IL-5, and IL-10. Thus, IPCs perform two key functions in antiviral immunity: directly inhibiting viral replication by producing IFN-α/β and subsequently triggering adaptive T cell-mediated immunity by differentiating into DCs. IPCs serve as a critical bridge between innate and adaptive immunity. The study shows that viruses can directly induce IPCs to differentiate into DCs without exogenous cytokines. This process is essential for initiating and directing adaptive immune responses. IPCs can also differentiate into Th2-inducing DCs in response to IL-3, suggesting their versatility in immune responses. The findings highlight the importance of IPCs in both innate and adaptive immunity, and their potential as therapeutic targets for infectious diseases, cancers, and allergic conditions.