The RoS2/SS-A autoantigen has elevated expression at the brain microvasculature

An expression cloning technique was used to identify proteins selectively expressed at the blood-brain barrier that may mediate interactions between the brain microvasculature and IgG molecules. Ro52/SS-A is an IgG-binding protein and is an autoantigen implicated in Sjogren's syndrome and systemic lupus erythematosus. The present studies describe the expression cloning of this gene product from a bovine brain microvascular cDNA library. The Ro52 protein interacted with IgG molecules independent of specificity suggesting a potential role as a general antibody receptor. Northern blotting shows the Ro52/SS-A transcript is enriched in the microvascular compartment of brain. The selective expression of Ro52/SS-A in brain at the microvasculature may play a role in brain vascular involvement in autoimmune diseases.