In addition, intercellular adhesion molecule-1 (ICAM-1, CD54) is highly expressed on astrocytes in the SN of PD patients and accordingly its receptor, lymphocyte function-associated antigen-1 (LFA-1) was observed on microglia and infiltrating leukocytes [27], indicating a role for immune regulation outside of the CNS. This evidence concerns the gene ICAM1 and Parkinson disease.