PPAR-γ expression in the human NKL cell line. (A) IL-4-induced PPAR-γ expression in NKL cells. NKL cells were cultured with IL-2, IL-15, or IL-2 plus IL-15 with or without IL-4 or IL-12 for 72 hours. RT-PCR was performed to detect transcripts for PPAR-γ, T-bet, and GAPDH. (B) Effect of IFN-γ on PPAR-γ expression. IFN-γ or antibody against IFN-γ (αIFN-γ) was added to IL-4-treated NKL cells cultured with either IL-2 or IL-15 for 72 hours. Transcripts for PPAR-γ, T-bet, and GAPDH were analyzed by RT-PCR. (C) IL-2, IL-4, IL-7, and IL-13 as well as GM-CSF were incubated with NKL cells for 24 hours. Expression of PPAR-γ, T-bet, and GAPDH were measured by RT-PCR. The PPAR-γ mRNA levels were presented as arbitrary units that were derived from average normalization densitometry values of each PPAR-γ band by corresponding GAPDH band or T-bet band.