DC-mediated HIV-1 transmission to LFA-1 negative T cells is impaired. DC were incubated with HIV-1, followed by washing to remove unbound virus. Subsequently, LAD-1 or control PBL were added to allow transmission of HIV-1. To prevent production of new virions, the cells were cultured in the presence of SQV (single-cycle transmission assay). 2 days after transmission, PBL were harvested and stained for CD3, DC-SIGN and intracellular CA-p24 to determine the transmission efficiency. (A) CD3 and DC-SIGN staining. (B) CA-p24+ CD3+ T cells of an uninfected sample. (C) and (D) Representative FACS staining of a healthy control and a LAD-1 patient, respectively. The percentage CA-p24+ CD3+ cells is indicated. (E) Kinetics of intracellular CA-p24 levels for a representative healthy and LAD-1 donor (n = 1). Error bars represent SD (F) Summary of HIV-1 transmission to T cells of healthy controls (n = 3) and LAD-1 patients (n = 3), two days post transmission. Error bars represent SEM. *P < 0.05, **P < 0.01, ***P < 0.001. One DC donor was used for all transmissions, to reduce variation.