FcγRIII, synonymously also referred to CD16, is a type III Fcγ receptor which has other two identified members: a high-affinity receptor FcγRI (CD64) and a low-affinity one FcγRII (CD32). This transmembrane protein, FcγRIII, contains two extracellular immunoglobulin (Ig)-like domains with low-affinity for IgG. It is responsible for antibody-dependent cellular cytotoxicity. FcγRIII is expressed on large granular lymphocytes of both nature killer (NK)- and T-cell types. There are two different isoforms of it in humans named FcγRIIIa and FcγRIIIb, sharing 96% sequence identity in extracellular Ig binding regions. FcγRIIIa is a transmembrane receptor found on macrophages, mast and NK cells. FcγRIIIb is expressed exclusively on neutrophils and functions as the only Fc receptor anchored via a glycosyl-phosphatidylinositol (GPI) linker to the cell membrane. CD33 (Cluster of differentiation 33), also known as p67 or SIGLEC-3 (Sialic acid binding Ig-like lectin 3), is a type I transmembrane glycoprotein of 67kDa. It is a sialoadhesin molecule belonging to the immunoglobulin supergene family and SIGLEC family of lectins. CD33 is a myeloid cell surface antigen that is specific for the myeloid lineage, but it also can be found on certain lymphoid cells as a restricted leukocyte antigen. It is expressed on myeloid stem cells, myeloblasts, monoblasts, monocytes/macrophages, granulocyte precursors, and mast cells. CD33 is a remarkable myeloid marker and is commonly applied in the diagnosis of acute myeloid leukemia (AML). And 10% to 20% of B lymphoblastic or T lymphoblastic leukemia/lymphomas are likely to aberrantly express CD33. CD19 (Cluster of differentiation 19), also known as B-lymphocyte antigen CD19, is a 95 kDa transmembrane glycoprotein on the surface of the immunoglobulin superfamily (IgSF) and classified as a type I one-pass transmembrane protein. It maps to the short arm of chromosome 16p11.2 encoded by the 7.41 kilobite CD19 gene that produces a 556-amino acid protein with two extracellular C-type IgSF domains together with a 242-residue cytoplasmic tail that exhibits highly conservation between mouse and human. The CD19 molecules are expressed from the earliest stage of B cells development until plasma cells terminal differentiation. It can associate with the B cell antigen receptor (BCR), CD81 (TAPA-1), CD38, CD21, CD22 and CD225 to establish intrinsic B cell signaling and reduce the thresholds.