CD69, also known as early activation antigen CD69, is a type 2 transmembrane glycoprotein in the C-type lectin family. Also, CD69 is a very early activation Ag of T lymphocytes. It is involved in lymphocyte proliferation and functions as a signal transmitting receptor in lymphocytes, natural killer (NK) cells, and platelets. This protein plays a role in the pathogenesis of allergen induced eosinophilic airway inflammation and responsiveness. Recombinant human CD69, fused to His-tag at C-terminus, was expressed in insect cell and purified by using conventional chromatography techniques.