Effects of anti-LFA–1 MoAb, anti-VLA–4 MoAb, anti-E–selectin MoAb, anti-OX40 MoAb, and anti-gp34 MoAb on the binding of ATL cells to HUVEC. PBMC from case no. 6 (A) were preincubated with 10 μg/mL of W6/32 (anti-MHC class I MoAb), TS1/18 (anti-CD18 MoAb), 315 (anti-OX40 MoAb), or HP2/1 (anti-VLA–4 MoAb). HUVEC were also preincubated with 10 μg/mL of 7A9 (anti-E–selectin MoAb), or 5A8 (anti-gp34 MoAb). The binding to unstimulated or IL-1–stimulated HUVEC was then determined as described in Materials and Methods. A similar assay was done with PBMC from case no. 13 (B) except that HP2/1 MoAb was omitted.