• brain;
  • endothelium;
  • blood–brain barrier;
  • adhesion molecules;
  • integrins;
  • immunohistochemistry

We studied the repertoire of junctional, cell–matrix and leucocyte–endothelial adhesion molecules normally expressed by cortical and subcortical brain microvessels, as compared with large intracranial vessels. An indirect immunoperoxidase method was applied to acetone-fixed cryostat sections of normal brain tissue obtained from 10 adult patients during surgical resections for intracranial aneurysms or at autopsy. Like large intracranial vessels, brain microvessels expressed the two endothelial-specific junctional cell adhesion molecules VE-cadherin and platelet–cell adhesion molecule-1. We verified that they also expressed the molecular components of adherens-type junctions, including catenins, plakoglobin, vinculin and α-actinin. Brain microvessels expressed a large repertoire of integrin molecules of the β1, β3 and β4 subfamilies. However, they displayed apparently lower levels of α2, α5, αV and β3 integrin chains than large intracranial vessels. Brain microvessels constitutively expressed large amounts of the leucocyte–endothelial adhesion molecules, intercellular adhesion molecule (ICAM)-2 and CD34 and very low amounts of ICAM-1 and lymphocyte function-associated antigen-3. In contrast to large intracranial vessels, brain microvessels presented no constitutive expression of P-selectin. Our study shows that, in contrast to their highly specific structural and functional characteristics, brain microvascular endothelial cells present a repertoire of cell adhesion molecules very similar to that of most other capillary vessels in the body.