In particular, regarding multiple sclerosis, available evidence indicates that β2-AR are decreased in astrocytes of patients, both in normal-appearing white matter as well as in chronic active and inactive plaques (De Keyser et al., 1999; Zeinstra et al., 2000), and it has been proposed that in this disease astrocytes may serve as primary (facultative) antigen-presenting cells due to a failure of β2-AR-mediated suppression of MHC II molecules (De Keyser et al., 2003). This evidence concerns the gene ADRB2 and multiple sclerosis.