Asuspected entry route for HIV turns out to be a dead-end, report Lot de Witte, Teunis Geijtenbeek (VU University Medical Centre, Amsterdam, Netherlands), and colleagues. Langerhans cells, rather than transmitting the virus to T cells, trap HIV-1 and thus act as a barrier to infection.
The primary targets for HIV-1 invasion are CD4-expressing T cells. HIV-1 uses the CD4 receptor to gain entry. The first immune cells that HIV-1 meets in the body's mucosa, however, are a subset of dendritic cells (DCs) called Langerhans cells (LCs). Most DCs internalize HIV-1 into nonlysosomal compartments and later transmit the virus to CD4-expressing T cells in lymphoid tissues. But in LCs, the team now shows, internalization is the end of the road for HIV-1.
Binding and internalization of HIV-1 to DCs depends on C-type cell surface lectins. The team shows that, on LCs, HIV-1 associates with a C-type...
