Figure 4.

Effect of over-expressing a dominant negative mutant of IκBα on cytokine-dependent increases in pIgR surface expression. HT29 cells were transfected with 100 MOI of an adenoviral vector expressing β -galactosidase (LacZ, controls for adenoviral effects) or IκBα-serine mutant (IκB) overnight. The indicated cytokine was then added (IL-4, 10 ng/ml; IFN-γ, 200 U/ml; both together) and cultures were incubated for 48 hr. Surface expression of the pIgR was quantitated using a cell-based ELISA as described in Materials and Methods. Data represent the mean ± standard deviation for triplicate samples. A significant decrease was observed with IκBα-serine mutant relative to the LacZ control; *P < 0.001. Similar results were seen in three independent experiments.