Listeria monocytogenes is a bacterial pathogen which establishes intracellular parasitism in various cells including macrophages and non-hematopoietic cells such as hepatocytes. At an early stage of L. monocytogenes infection of mice, a pro-inflammatory cytokine interleukin (IL)-22 was expressed by CD3+ CD4+ T cells. To address influence of IL-22 on L. monocytogenes infection to hepatocytes, a human hepatocellular carcinoma line HepG2 was treated with IL-22 before L. monocytogenes infection in vitro. Gene expression analysis of the IL-22-treated HepG2 cells identified phospholipase A2 group IIA (PLA2G2A) as an up-regulated antimicrobial molecule. Addition of recombinant PLA2G2A into the HepG2 culture significantly suppressed L. monocytogenes infection. Culture supernatant of the IL-22-treated HepG2 contained bactericidal activity against L. monocytogenes, and the activity was abrogated by a specific PLA2G2A inhibitor, demonstrating that the HepG2 secreted PLA2G2A and killed extracellular L. monocytogenes. Furthermore, co-localization of PLA2G2A and L. monocytogenes was detected in the IL-22-treated infected HepG2, which suggests involvement of PLA2G2A in intracellular killing mechanism of HepG2 against intracellular L. monocytogenes. These results suggest that IL-22 induced at an early stage of L. monocytogenes infection enhances innate immunity against L. monocytogenes in the liver by stimulating hepatocytes to produce an antimicrobial molecule PLA2G2A.