Thus, increased expression of markers of macrophage or microglial activation and inflammatory cytokines, accompanied by decreased expression of CD200 has been observed in active and inactive lesions in the CNS obtained from postmortem tissue of individuals with multiple sclerosis [6] and a decrease in expression of CD200 has been reported in areas of the brain which exhibit pathology in Alzheimer’s disease [36]. Here, CD200 is linked to early-onset autosomal dominant Alzheimer disease.