DC-SIGN–Expressing Tonsil B Cells Mediate <i>trans</i> Infection of T Cells

<div><p>(A) Expression of CD20 and DC-SIGN or CD23 and DC-SIGN in fresh (time 0 h; T0) and IL-4– and CD40L-activated (time 24 h; T24) B cells derived from tonsils. Data are from one experiment representative of five independent experiments.</p><p>(B) Levels of HIV-1 p24 in co-cultures of B and T cells derived from tonsils. B cells were stimulated with IL-4 and CD40L for 24 h, treated with anti–DC-SIGN mAb or mouse Ig (20 μg/ml) or left untreated, and loaded with 10⁻⁴ MOI of HIV-1 R5 (Ba-L) for 2 h at 37 °C, then extensively washed in cold medium and incubated with purified, autologous CD4⁺ T cells (T). B cells and T cells directly loaded with HIV-1 served as controls. Amount of HIV-1 p24 in the cell culture supernatants was determined by ELISA. Data are from one experiment representative of two independent experiments.</p>