Figure 6.

Combined use of anti-CD2 and anti-NKG2D monoclonal antibodies (mAbs) in the presence of a sub-optimal concentration of PD98059 additively suppressed natural killer (NK) cytotoxicity. (a) Western blotting was performed to assess extracellular signal-regulated kinase (ERK) phosphorylation upon stimulation with MPN3. Interleukin-2 (IL-2) -activated human primary NK cells were co-incubated with fixed MPN3 and cells were harvested at designated times for lysis. Upper bands represent phosphorylated ERK1/2 and lower bands represent total ERK1/2 proteins. (b) A standard ⁵¹Cr-release assay was performed with IL-2-activated human primary NK cells as effector cells and MPN3 as target cells. NK cells were pre-incubated with PD98059 at designated concentrations for 30 min before the assay. Specific lysis (%) was presented as mean + SD of triplicates. The data are representative of five independent experiments. (c) IL-2-activated human primary NK cells were pre-incubated with 50 μmPD98059 and/or 10 μg/ml designated blocking mAb(s) for 30 min before the assay. A standard ⁵¹Cr-release assay was performed with the cells against MPN3. Specific lysis (%) was presented as mean + SD of triplicates. The data are representatives of minimum three independent experiments.