ICAM1 and oral lichen planus: Efalizumab inhibits the binding of leukocyte function antigen-1 (LFA1) to the intercellular adhesion molecules-1 (ICAM-1), thereby inhibiting the adhesion of leukocytes to other cell types lead to the improvement of OLP via decreased activation and trafficking of T lymphocytes, which play a vital role in its pathologic development of OLP.