CD48 antigen (also known as signaling lymphocytic activation molecule 2, SLAMF2, BLAST-1) is a member of the signalling lymphocyte activation marker (SLAM) family. CD48 belongs to immunoglobulin superfamily. Its structure includes Ig variable-like domain and Ig constant-like domain. 2 isoforms of CD48 have been described in humans. It is currently not known whether they serve different purposes, desipte distinction in lenght and C termini sequences. Membrane-bound and soluble forms of CD48 have been observed. CD48 is being expressed constitutively on almost all hematopoietic cells. Its expression is being icreased in peripheral blood mononuclear cells under inflammatory conditions. Proteins capable of binding to CD48 include CD2, CD244 and E. coli lectin FimH. Interaction of CD48 and its ligands are influenced by their expression patterns, expression pattern of CD58 (CD48 analog in humans, exhibiting high affinity binding to CD2) as well as respective binding affinities. CD48 plays a role in multiple processes, such as autoimmunity, inflammation, allergy, infection, graft rejection and hematopoiesis. In particular, costimulatory effect of CD48 includes promoting TCR signaling and T cell activation and enhanced cytotoxicity of CD8+ T cells. It also influences activity of NK cells. (1)

1. McArdel, S. L., Terhorst, C., & Sharpe, A. H. (2016). Roles of CD48 in regulating immunity and tolerance. Clinical immunology, 164, 10-20.