Figure 2.

IL-2 activated NK cells from Cox-2^flox/flox;LysM^Cre/+ mice cultured with autologous monocytes lysed YAC-1 cells and secreted high levels of IFN-γ as compared to NK cells from control littermates in the presence and absence of autologous monocytes. NK cells obtained from control mice or Cox-2^flox/flox;LysM^Cre/+mice were left untreated or treated with IL-2 (1 × 10⁴ U/million) in the presence or absence of autologous monocytes for 7 days. Afterward, the cytotoxic function of NK cells against YAC-1 cells was determined using a standard 4 h ⁵¹Chromium release assay. *P < 0.05 was obtained for the difference in cytotoxicity against YAC-1 tumors mediated by IL-2-treated NK cells cultured with or without monocytes between control and Cox-2^flox/flox;LysM^Cre/+ mice (A). NK cells were treated as described in (A) Afterward, the supernatants were removed from the co-cultures and the levels of IFN-γ secretion were determined using specific ELISAs (B). *P < 0.05 was obtained for the difference in IFN-γ secretion from IL-2-treated NK cells between control and Cox-2^flox/flox;LysM^Cre/+ mice cultured with monocytes. One of several representative experiments is shown in this figure.