CD84, also known as slam family member 5 isoform 1, is a self-binding receptor from the CD150 family that is broadly expressed in hematopoietic cells. It is highly expressed in mast cells and that it contributes to the regulation of Fc?RI signaling in SAP- and EAT-2-independent and Fes- and Src homology region 2 domain-containing phosphatase-1-dependent mechanisms. It belongs to the signaling lymphocyte activating molecule family of immunoreceptors, and has an unknown function in CLL cells. Its expression is significantly elevated from the early stages of the disease, and is regulated by macrophage migration inhibitory factor and its receptor, CD74. Recombinant human CD84, fused to His-tag at C-terminus, was expressed in insect cell and purified by using conventional chromatography techniques.