CD48 is a glycosylphosphatidylinositol (GPI) -anchored membrane protein of the signaling lymphocyte activation molecule (SLAM) family, also known as SLAMF2 and BLAST-1. It is constitutively expressed on most hematopoietic cells (not on neutrophils and a subset of long-term hematopoietic stem cells in mice) and can be upregulated under certain conditions like infection. Interaction with its low affinity ligand CD2 promotes adhesion and TCR signaling. Interaction with the high affinity ligand CD244 (2B4) regulates natural killer (NK) and CD8 T cell activation and cytolytic function.