The HM48-1 antibody reacts with mouse CD48, a 45 kDa GPI-anchored glycoprotein and a member of the signaling lymphocyte activation molecule (SLAM) family and Ig superfamily. SLAM family members play a role in multiple aspects of immune function including costimulation, cytotoxicity, and cytokine production. CD48 also plays a role in cell adhesion and T cell activation. In mice, CD48 is thought to be present on nearly all hematopoietic cells except neutrophils and ESLAM cells (CD45+EPCR+CD48-CD150+ hematopoietic stem cells with long-term self-renewal capacity). Ligands for CD48 include CD2 and CD244, binding of which helps to promote interactions between immune cells. HM48-1 is reported to be capable of blocking CD48:CD2 and CD48:CD244 interactions in vitro and in vivo. HM48-1 is also reported to inhibit the proliferative response of spleen cells to mitogens, inhibit CTL activity, and enhance the survival of cardiac allografts.