Model of a positive regulatory loop of IFN-γ-IL-18 signaling in memory CD8⁺ T cell expansion.

Unlike naïve CD8⁺ T cells, memory CD8⁺ T cells can provide an early source of IFN-γ to stimulate more IL-18 production from DCs. This positive loop of IFN-γ-IL-18 signaling may play an amplifying role in the acceleration of CD8⁺ T cell expansion in memory response rather than in primary response.