Inhibition of LC infection with the T-tropic NL4-3 by a CXCR4/fusin ligand, SDF-1, and by an anti-CXCR4/fusin MoAb (12G5). Purified LC were pretreated with SDF-1 (125 nmol/L), 12G5 (10 μg/mL), or the chemokines indicated and pulsed with NL4-3 (6 ng/mL of p24) and incubated for 16 hours, washed five times, trypsinized, washed two times, and cocultivated with heterologous, activated T cells. SDF-1, 12G5, or chemokines were no longer added during this phase II. The level of p24 released into the medium was measured on day 4 of cocultivation.