CD15 is 3-fucosyl-N-acetyllactosamine (3-FAL) also known as Lewis X, 3-FAL, X-hapten, and SSEA-1. CD15 is expressed on granulocytes and monocytes. It has also been shown to be expressed on Langerhans cells. CD15 has been implicated in adhesion as well as chemotaxis, phagocytosis, and bactericidal activity.