Immunocytolocalization of ATP synthase at the junction between HIV-1–primed DCs and target cells. MDDCs were incubated with HIV-1 for 3 hours, washed, and added to target cells either TZM cells (A) or HUT/CCR5 cells (B,D) in the presence of anti-ATP synthase β-chain antibodies. (C) Same as in panel A, only that the incubation was done without the virus. (D) Same as in panel B, only that MDDCs were stained in green and HUT/CCR5 were stained in blue as described in “Confocal microscopy.” For all samples, staining was carried out with Alexa-555–anti–mouse IgG secondary antibody, the sample was fixed, and the pattern was visualized by confocal microscopy as described in “Methods.”