Figure 1. Murine macrophages increase NK cell cytotoxicity to susceptible target cells.

Freshly purified splenic NK cells were first co-cultured with untreated or poly I:C-pretreated macrophages for 24 h at an NK/macrophage ratio of 5∶1, and then separated by vibrating gently to be used as effector cells against susceptible target cells. NK cell-mediated lysis against YAC-1 cells, Hepa1-6 cells, MCA38 cells, H22 cells (A), RAW264.7 cells (B) or peritoneal Mφ (C) was assessed by the ⁵¹Cr release assay at various E:T rations. Data are expressed as the mean ± SD from at least three separate experiments. *p<0.05, **p<0.01 versus untreated cells using the paired Student’s test.