CNS microvascular pericytes express macrophage-like function, cell surface integrin alpha M, and macrophage marker ED-2.

CNS pericytes are an integral part of the blood-brain (BBB), but their function is not well understood. We questioned whether primary cultured CNS pericytes have immune potential. Primary cultured pericytes exhibit phagocytic activity when exposed to fluorochrome-conjugated polystyrene beads and antibody-coated zymosan. Maximum phagocytic activity occurred by 3 hr. Pericytes were found to express the macrophage markers ED-2 and the integrin subunit CD11b (alpha M) in culture as well as on isolated microvessels. Pericytes did not express the macrophage marker ED-1. We confirm the heterogeneity of cultured CNS pericytes with regard to expression of alpha-smooth muscle actin. In conclusion, pericytes express macrophage surface antigens and have the ability to perform at least some immune function. CNS pericytes may therefore have a role in neuroimmune networks at the BBB.