LAIR-1

Leukocyte-associated immunoglobulin-like receptor 1 (LAIR-1), also known as CD305, is a transmembrane glycoprotein inhibitory receptor characterized by an extracellular C2-type Ig-like domain and two ITIMs in the cytoplasmic tail. It is expressed not only on NK cells but also on other cells of innate immunity (such as monocytes, granulocytes, dendritic cells, mast cells, macrophages), on T and B lymphocytes, on CD34+ hematopoietic progenitor cells and on the majority of thymocytes. During the process of cell maturation and activation, LAIR-1 expression is decreased on various immune cells (i.e., CD4+ T cells, neutrophils, B cells). The interaction between LAIR-1 and its several ligands, such as extracellular matrix collagens, the C1q complement component, and the surfactant protein D, induces phosphorylation of both ITIMs and inhibition of the immune cell activation or differentiation. LAIR-1 plays a role in controlling various phases of the immune response and is considered to be an immune checkpoint in different inflammatory diseases.