LFA3 is a type 1 transmembrane glycoprotein and a member of the immunoglobulin superfamily of cell surface receptors. It is expressed on most hematopoietic cells and on nonhematopoietic cells such as fibroblasts，endothelial and epithelial cells. Its expression is particularly high on memory T-cells and dendritic cells. LFA3 expression on antigen-presenting cells and target cells enhances T-cells antigen recognition through binding to its ligand，LFA2/CD2，on T-cells.