Leukocyte differentiation antigen CD84 is also known as SLAM family member 5 (SLAMF5), which belongs to immunoglobulin (Ig) superfamily. CD84 / SLAMF5 contains one Ig-like C2-type (immunoglobulin-like) domain. CD84 plays a role as adhesion receptor functioning by homophilic interactions and by clustering. CD84 / SLAMF5 increases proliferative responses of activated T-cells and SH2D1A/SAP does not seen be required for this process. Homophilic interactions enhance interferon gamma/IFNG secretion in lymphocytes and induce platelet stimulation via a SH2D1A/SAP-dependent pathway.