Staining for the activated form of LFA-1α (CD11a) on peripheral ATL cells using NKI-L16 MoAb. Peripheral normal T cells (a) and ATL cells (b through f) were pretreated with or without 1 μg/mL pertussis toxin for 1 hour at 37°C (c), 100 nmol/L wortmannin (d), 10 μmol/L herbimycin A (e), or a mixture of anti–MIP-1α and anti–MIP-1β Abs (f) for 2 hours at 37°C. The cells were subsequently stained with CD11a MoAb TS1/22 or NKI-L16 MoAb. Cells in the CD4 and CD45RO gate (triple fluorescence) were analyzed by using a flow cytometer. Representative histograms from each one of the volunteers or patients are shown.