Presence of OX40-OX40L complexes in HTLV-1+T cell lysates. The ILT-H2 cell line derived from an ATL patient were lysed and the lysates incubated in microtiter wells that had been previously coated with either anti-CD25, OX40 or OX40L mAb for 1 hour. Anti-CD25 mAb was used as a non-specific negative control. After washing, the levels of OX40 or OX40L bound to the plates were assayed using either HRP-labeled anti-OX40 or anti-OX40L mAb. Data shown are representative of 3 independent experiments.