Phenotypic analysis of fresh ATL cells by flow cytometry. Staining and flow cytometric analyses of resting peripheral blood T cells from 10 normal volunteers (○) and ATL cells freshly obtained from peripheral blood of 20 ATL patients (•) were performed with (a) LFA-1α (CD11a) MoAb TS1/22, (b) VLA-4 α (CD49d) MoAb NIH49d-1, (c) an anti-activated form of LFA-1α MoAb NKI-L16, and (d) CD69 MoAb by gating on CD4 and CD45RO double-positive cells using FACScan. Each point represents the number of molecules expressed per cell, calculated using standard QIFKIT beads. Bars represent the mean ± SD of each group and statistical significance was determined by the Student's t-test.