Scavenger receptor class B type I (SR-BI) mediates adhesion of neonatal murine microglia to fibrillar β-amyloid

Class A scavenger receptors (SR-A) mediate microglial interaction with fibrillar beta -amyloid (fA beta). We report here that neonatal microglia from SR-A knockout mice (SR-A(-/-)) adhere to surface-bound fA beta, and produce reactive oxygen species (ROS) as efficiently as wildtype microglia; that both wildtype and SR-A(-/-) microglia express SR-BI; that antibodies against SR-BI do not affect adhesion or ROS production by wildtype microglia, but inhibit adhesion and ROS production of SR-A(-/-) microglia to immobilized fA beta by similar to 40%. Adhesion to fA beta -coated surfaces, and uptake of fA beta by both wildtype and SR-A(-/-) microglia was almost completely inhibited by incubation with fucoidan. Thus SR-BI and SR-A mediate similar effector functions in neonatal microglia, which suggests that SR-BI plays as important a role as SR-A, and can maintain the wildtype phenotype in SR-A(-/-) microglia. (C) 2001 Elsevier Science BN. All rights reserved.