Tat tethered to the surface of HIV⁺ ACH-2 T lymphocytes and Namalwa cells promotes their adhesion to ECs. (A) Namalwa cells were preincubated for 2 hours with GST-Tat (550 nM) and washed with PBS or with PBS/NaCl. (B) EV-NCs and SYN-NCs were pretreated with heparinase III (10 mU/mL), incubated for 2 hours with s-Tat (550 nM), and washed with PBS. (C) ACH-2 or CEM A3.01 cells were left untreated or subjected to heparinase III treatment (20 mU/mL) and then analyzed by cytofluorimetry using a polycolonal FITC-coupled anti-Tat antibody. (D) The same cells were washed with PBS or with PBS/NaCl and allowed to adhere to naive EC monolayer. (E) Namalwa cells transfected with a cDNA encoding for Tat were washed with PBS or PBS/NaCl. Then, cells were allowed to adhere to naive EC monolayer and adherent lymphocytes counted. (F) Western blot analysis with anti-Tat antibodies of Tat-transfected Namalwa cells (600 000 cells). Tat indicates s-Tat (17 pmol); n.t., not transfected; and t., transfected.