CUTTING EDGE - HUMAN MYELOMONOCYTIC CELLS EXPRESS AN INHIBITORY RECEPTOR FOR CLASSICAL AND NONCLASSICAL MHC CLASS-I MOLECULES

Leukocyte activation can be negatively regulated by inhibitory recepto rs specific for MHC class I molecules, While one inhibitory receptor, Ig-like transcript 2 (ILT2), is expressed by all lymphoid and myelomon ocytic cell types, other receptors display a more selective tissue dis tribution, Here we characterize an inhibitory receptor, termed ILT4, w hich is selectively expressed in monocytes, macrophages, and dendritic cells (DCs), binds classical class I molecules and the nonclassical c lass I molecules HLA-G, and transduces negative signals that can inhib it early signaling events triggered by stimulatory receptors. ILT4 may control inflammatory responses and cytotoxicity mediated by myelomono cytic cells and may modulate their Ag-presenting functions, focusing i mmune responses to microbial challenges and avoiding autoreactivity.