Macrophages Help NK Cells to Attack Tumor Cells by Stimulatory NKG2D Ligand but Protect Themselves from NK Killing by Inhibitory Ligand Qa-1
Figure 5
Qa-1 contributes to the protection of macrophages from NK cell-mediated lysis.
Changes in mRNA and protein levels of the NKG2A ligands Qa-1a and Qa-1b (A,B), and the NKG2D ligands RAE-1, H60, and MULT-1 (C) in YAC-1 cells, macrophages (Mφ) or RAW264.7 cells were detected by RT-PCR or FACS. Data are expressed as relative expression from at least three separate experiments. *p<0.05, **p<0.01 versus YAC-1 mRNA levels using the paired Student’s test. RAW264.7 cells first stimulated with 100 µg/ml poly I:C for 24 h and then co-incubated with saturating amounts of anti-Qa-1 mAb or isotype control or transfected with si-Qa-1 or si-control, were then used as target cells. The cytolytic activity of NK cells stimulated with poly I:C-treated macrophages was assessed at various E:T rations (D). Data are expressed as the mean ± SD from at least three separate experiments. *p<0.05, **p<0.01 compared with the isotype control or si-control group.