Activation of LFA-1 is crucial for efficient HIV-1 transmission. (A) Single-cycle transmission assay. Two days after DC-mediated transmission in the presence of SQV, PBL were harvested and stained for CD3, DC-SIGN and intracellular CA-p24 to determine the percentage of HIV-1 positive T cells. Experiments were performed twice with cells from the same patient isolated on two separate occasions. Cells of two different healthy controls were used. Error bars represent SD. *P < 0.02. (B) Viral replication in T cells after DC-mediated transmission to healthy and LAD-1/variant PBL was followed by CA-p24 ELISA of the supernatant. (C) LAD-1/variant PBL or control cells were stimulated with anti-CD3/CD28 antibodies and were infected with HIV-1. Viral replication was followed by CA-p24 ELISA.