Measurement of acute phase proteins in the rat brain: Contribution of vascular contents

A localized acute phase response occurs in the brain in Alzheimer's disease . Acute phase proteins have previously been measured in brain homogenates t o quantify this response. The extent to which measurements of these protein s reflect brain parenchymal contents, as opposed to vascular contents, is u nknown. In this study, the acute phase proteins ceruloplasmin (CP), complem ent factor 3 (C3), haptoglobin (HP), and albumin were measured in regional brain homogenates from phosphate buffered saline-perfused and sham-perfused rats (n = 7-9/group). Interleukin I-P (IL1-beta) and copper were also meas ured. Mean CP, C3, HP, and albumin concentrations in perfused specimens dec reased by 94%, 884b, 90%, and 81% vs. sham-perfused specimens (all p < 0.00 1), while IL1-beta and copper were unchanged. These results suggest that ac ute phase protein measurements in brain homogenates reflect primarily vascu lar contents. However, IL1-beta and copper concentrations in brain homogena tes are minimally influenced by vascular contents.