Background：CD28 is a 44 kD glycoprotein, also known as Tp44 or T44. It is a member of the Ig superfamily, expressed on thymocytes, most peripheral T cells, and NK cells. In association with CD80 （B7-1） and CD86 （B7-2）, CD28 acts as the second signal for T and NK cell activation and proliferation. The 37.51 antibody has been reported to augment in vitro T cell proliferation and cytokine production, and promote CTL development.
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.
