CD48

null CD48 (BLAST-1, BCM1, MEM-102, TNFRSF-like) is a glycosylphosphatidylinositol-anchored member of the SLAM (signaling lymphocyte activation molecule) family within the CD2 superfamily, lacking a cytoplasmic tail and depending on lipid raft localization for signaling. CD48 is abundantly expressed on virtually all hematopoietic cells except erythrocytes and platelets-resting and activated lymphocytes, monocytes, eosinophils and dendritic cells-upon activation through cytokine or antigen receptor stimuli. CD48 interacts with CD2 (low affinity), 2B4/CD244 (its high-affinity receptor on NK cells and cytotoxic lymphocytes) and, in rodents, with CD48 itself; engagement of 2B4 by CD48 delivers activating signals in mouse NK cells through SAP-Fyn, but inhibitory signals in human NK cells via SHP-1/SHP-2 and Csk when SAP is absent. CD48 also serves as a receptor for certain viruses and bacteria, facilitating HIV infection and mycoplasma binding, and is overexpressed in EBV-associated lymphoproliferations, making CD48-targeted immunotoxins an experimental therapeutic concept.