FIG. 5.

ICAM-1- LFA-1 interactions are responsible for more rapid attachment and fusion of ICAM-1-bearing virions. PM1 cells (A), PBMCs (B), and purified CD4⁺ T lymphocytes (C) were initially pretreated for 60 min at 37°C with the blocking anti-LFA-1 antibody MEM30. The cells were next incubated at 37°C for 30 min with similar amounts of isogenic NL4-3 particles either bearing or not bearing ICAM-1 (100 ng of p24). The cells were extensively washed with PBS and treated with trypsin to remove uninternalized virions before lysis to quantify the amount of virus that had entered the cells. Experiments were performed in triplicate, and standard deviations are indicated. The data shown are representative of three separate experiments. The asterisks indicate a significant difference from cells inoculated with NL4-3/ICAM-1 that were not treated with MEM30 (CTRL) (P < 0.02).