Activated endothelium can up-regulate the expression of 4 integrins on NQ22 cells.

H-end80 cells grown to confluence were left untreated (upper panels) or were treated for 16 hours with 10 ng/mL TNF-α (lower panels) and then were cocultured for 24 hours with NQ22 or NQ29 cells grown in vitro. At the end of the incubation period, NQ cells were collected, the expression of α4 integrin subunit was determined with the use of PS/2 mAb, and the reactivity was examined by confocal fluorescence microscopy with pseudocolor enhancement. NQ22 cells from heavily infiltrated spleen (NQ22 vivo) were used as positive control. Selected fields with a relatively higher percentage of positive cells were chosen for display for NQ22 and NQ29 cells (A), whereas the percentage of positive cells is graphically depicted (B).