Expression of epitopes recognized by activating mAbs NKI-L16 (anti-αL), KIM 127 (anti-β2), 240Q (anti-β2), and 24 (anti-αL activation reporter) on J-β2.7 cells expressing wt LFA-1 or ΔI-LFA-1. Cells were stained on ice with the relevant mAbs followed by FITC-conjugated goat anti-mouse IgG and analysis by flow cytometry. Dotted lines, negative control; thick lines, mAb G25.2; filled histograms, activating mAbs. Data for each set of mAbs are from experiments conducted in parallel, and one experiment representative of three is shown.