CD69 is a phosphorylated disulphide-linked dimmer composed of two chains of 27 kDa and 33 kDa, and also known as activation inducer molecule (AIM). CD69 is the earliest inducible surface antigen expressed on lymphocytes after T and B cell activation. CD69 is absent from resting lymphocytes (Sanchez-Madrid, 1995). Other cells, including epidermal Langerhans cells, natural killer (NK) cells, eosinophils, neutrophils, and platelets may also express CD69 (Poggi, 2002). In vitro studies have demonstrated a transient expression of CD69 on activated T cells. After activation, surface expression can be detected within 2-4 hours, reaching a maximum after 18-24 hours followed by a gradual decrease (Hara, 1986). CD69 is thus detectable prior to other activation antigens like CD25 and CD71. CD69 is believed to be involved in signal transduction, since cross-linking with anti-CD69 induces activation (Testi, 1989).
CD69; CD69 antigen; early activation antigen CD69; Very Early Activation Antigen; AIM; VEA; AI452015; 5830438K24Rik; CD69 molecule; CD69 antigen (p60, early T cell activation antigen); CLEC2C; leukocyte surface antigen Leu-23; early T-cell activation antigen p60; early lymphocyte activation antigen; activation inducer molecule (AIM/CD69); C-type lectin domain family 2, member C; CD69 antigen (p60, early T-cell activation antigen); EA1; MLR-3; GP32/28; BL-AC/P26; CD69 antigen (p60; C-type lectin-like receptor; early T-cell activation antigen)