CD48 antigen, also known as B-lymphocyte activation marker BLAST-1, BCM1 surface antigen, Leukocyte antigen MEM-102, TCT.1, CD48, BCM1,and BLAST1, CD48 contains one Ig-like C2-type domain and one Ig-like V-type domain, but does not have a transmembrane domain, however, but is held at the cell surface by a GPI anchor via a C-terminal domain which maybe cleaved to yield a soluble form of the receptor. CD48 may facilitate interaction between activated lymphocytes and be involved in regulating T-cell activation. CD48 plays a vital role as an environmental sensor for regulating progenitor cell numbers and inhibiting tumor development. It is suggested that the anti-CD48 mAb has the potential to become an effective therapeutic mAb against multiple myeloma.