THE BLOOD-BRAIN-BARRIER AND THE INFLAMMATORY RESPONSE

The environment of the brain is controlled by a sophisticated endothel ial barrier that prevents the free entry of solutes from the blood, It is commonly assumed that this brood-brain barrier (BBB) also prevents the entry of leukocytes into the central nervous system. However, rec ent evidence in animal models shows that this is not the case, and leu kocytes can cross an intact BBB during health and disease, Indeed, in many neurological diseases, including Alzheimer's disease, prion disea ses and AIDS-related dementia, leukocytes enter the brain parenchyma w ithout concomitant BBB breakdown, Current research is concentrating on factors that control the integrity of the BBB and the mechanisms that leukocytes use to enter the brain.