To know whether the antigen-specific IL-1β induction in APCs by CTLs contributes to host defense against intracellular bacterial or viral infections, we utilized β2M-deficient mice because β2M-deficient mice are reported to have no functional CTLs and β2M was required for antigen-specific CTL-mediated IL-1β induction in APCs (Fig. 3c,g). Here, IL1B is linked to viral infectious disease.