Background：CD4, also known as T4/Leu-3, is a 55 kD single-chain type I transmembrane glycoprotein and member of the immunoglobulin superfamily. It is expressed on most thymocytes, helper T cells, type II NKT cells, and monocytes/macrophages. CD4 is part of the TCR/CD3 complex, binds to b2 domain from the MHC class II molecule, and participates in TCR signal transduction. CD4 is the receptor of IL-16 and is a coreceptor for the human immunodeficiency virus （HIV） and human herpes virus 7 （HHV-7）.
Buffer：0.2 um filtered in PBS, pH7.2. Azide Free （AF）/Low Endotoxin （LE）： Contains no stabilizers or preservatives. Endotoxin level is ＜ 2 EU/mg （ ＜ 0.002EU/ug） as Determined by LAL gel clotting assay.
