CD85d/ILT-4
CD85d, known as immunoglobulin-like transcript 4 (ILT-4, LILRB2, LIR-2), is an inhibitory leukocyte immunoglobulin-like receptor expressed on monocytes, macrophages, dendritic cells and granulocytes but absent from T and NK cells. Four extracellular immunoglobulin-like domains engage HLA class I molecules, and ligand binding recruits SHP-family phosphatases through cytoplasmic immunoreceptor tyrosine-based inhibitory motifs, suppressing Fc receptor and Toll-like receptor pathways. By favoring tolerogenic dendritic-cell states, ILT-4 shapes myeloid crosstalk with T lymphocytes; its expression on tumor-associated macrophages correlates with immunosuppression, making it a candidate myeloid checkpoint, and a soluble form circulates in plasma.
