Molecular characterization of two novel C-type lectin-like receptors, one of which is selectively expressed in human dendritic cells.

We have identified two human C-type lectin-like receptors, CLEC-1 and CLEC-2. Both display a single carbohydrate recognition domain and a cytoplasmic tyrosine-based motif. They are homologous to the NK cell receptors NKG2s and CD94 and also to the oxidized low-density lipoprotein receptor 1.

Human myeloid cells express an activating ILT receptor (ILT1) that associates with Fc receptor gamma-chain.

Ig-like transcripts (ILTs) encode cell surface receptors expressed on myeloid and lymphoid cells that are structurally and functionally related to killer cell inhibitory receptors. One ILT, designated ILT1, contains a short cytoplasmic domain that lacks sequence motifs implicated in signal transduction. Its function is unknown.

Human myelomonocytic cells express an inhibitory receptor for classical and nonclassical MHC class I molecules.

Leukocyte activation can be negatively regulated by inhibitory receptors specific for MHC class I molecules. While one inhibitory receptor, Ig-like transcript 2 (ILT2), is expressed by all lymphoid and myelomonocytic cell types, other receptors display a more selective tissue distribution. Here we characterize an inhibitory receptor, termed ILT4, which is selectively expressed in monocytes, macrophages, and dendritic cells (DCs), binds classical class I molecules and the nonclassical class I molecules HLA-G, and transduces negative signals that can inhibit early signaling events triggered by stimulatory receptors.

A common inhibitory receptor for major histocompatibility complex class I molecules on human lymphoid and myelomonocytic cells.

Natural killer (NK) cell-mediated lysis is negatively regulated by killer cell inhibitory receptors specific for major histocompatibility complex (MHC) class I molecules. In this study, we characterize a novel inhibitory MHC class I receptor of the immunoglobulin-superfamily, expressed not only by subsets of NK and T cells, but also by B cells, monocytes, macrophages, and dendritic cells. This receptor, called Ig-like transcript (ILT)2, binds MHC class I molecules and delivers a negative signal that inhibits killing by NK and T cells, as well as Ca2+ mobilization in B cells and myelomonocytic cells triggered through the B cell antigen receptor and human histocompatibility leukocyte antigens (HLA)-DR, respectively.