LANGERIN: A NATURAL BARRIER TO HIV TRANSMISSION BY LANGERHANS CELLS.

Langerin is a natural barrier to HIV-1 transmission
by Langerhans cells.

Human immunodeficiency virus-1 (HIV-1) is primarily transmitted sexually.
 
Dendritic cells (DCs) in the subepithelium transmit HIV-1 to T cells through the C-type lectin DC-specific intercellular adhesion molecule (ICAM)-3-grabbing nonintegrin (DC-SIGN).
 
However, the epithelial Langerhans cells (LCs) are the first DC subset to encounter HIV-1.

It has generally been assumed that LCs mediate the transmission of HIV-1 to T cells through the C-type lectin Langerin, similarly to transmission by DC-SIGN on dendritic cells (DCs).
 
Here we show that in stark contrast to DC-SIGN, Langerin prevents HIV-1 transmission by LCs.
 
HIV-1 captured by Langerin was internalized into Birbeck granules and degraded.

Langerin inhibited LC infection and this mechanism kept LCs refractory to HIV-1 transmission; inhibition of Langerin allowed LC infection and subsequent HIV-1 transmission.
 
Notably, LCs also inhibited T-cell infection by viral clearance through Langerin.

Thus Langerin is a natural barrier to HIV-1 infection, and strategies to combat infection must enhance, preserve or, at the very least, not interfere with Langerin expression and function.

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de Witte L, Nabatov A, Pion M, Fluitsma D, de Jong MA, de Gruijl T, Piguet V, van Kooyk Y, Geijtenbeek TB.

Department of Molecular Cell Biology and Immunology,
VU University Medical Center,
van de Boechorstraat 7,
1081BT Amsterdam,
The Netherlands.

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