T cell-intrinsic factors contribute to the differential ability of CD8+ T cells to rapidly secrete IFN-γ in the absence of antigen.

A subset of CD44(hi)CD8(+) T cells isolated from C57BL/6/J (B6) mice, but not BALB/c/By/J (BALB/c) mice, rapidly secrete IFN-γ within 16 h of infection with Listeria monocytogenes. This Ag-independent response requires the presence of both IL-12 and IL-18. Previous studies showed that dendritic cells from B6 mice produced more Th1-type cytokines such as IL-12 than did those from BALB/c mice in response to L.