Serum amyloid P is not present in amyloid beta deposits of a transgenic animal model

SERUM amyloid P component (SAP) is associated with amyloid beta (A beta) de position in Alzheimer disease (AD). Since SAP is exclusively synthesized by peripheral organs, its presence in the brain of A beta suggests impairment of the blood-brain barrier (BBB). We studied the association of SAP with A beta deposits in a transgenic mouse model overexpressing beta-protein prec ursor (X PP). Both SAP and another extracellular matrix binding protein, ba sic fibroblastic growth factor bind to the heparinase sensitive sites of A beta deposits in this model. However, no endogenous SAP immunoreactivity wa s found in the transgenic mouse brain. These results suggest that SAP is no t required for A beta deposition, and that this mouse model does not develo p the same BBB abnormalities as those seen in AD. (C) 1999 Lippincott Willi ams & Wilkins.