Immunohistochemical detection of defensin in cerebral vessels. (A) Cerebral vessel with mild thickening of the intima due to atherosclerotic changes. Note focal immunostaining for defensin within the cytoplasm of endothelial cells and occasional intimal cells. (B) A more severely affected vessel with extensive endothelial cell and intimal staining for defensin and staining of occasional cells within the media. (C) An advanced atherosclerotic plaque with intense, diffuse immunostaining for defensin, predominantly in extracellular locations. (D) Atherosclerotic vessel incubated with control Ig. (E and F ) Comparison between staining for defensin (E) and Lp(a) (F ) in adjacent sections of an atherosclerotic cerebral vessel. In some portions of the vessel, defensin and Lp(a) are coexpressed in the endothelium and portions of the intima (left side), whereas in other regions the distribution of the two molecules differs slightly (right side). This slide is representative of the finding that Lp(a) was found in the absence of defensin predominantly in less cellular regions of the vessel wall, whereas staining for defensin was more focal and cell-associated and reached deeper into the intimal, media, and adventitia. (G) and (H) are adjacent sections taken from the margin of an atherosclerotic plaque. The internal elastic membrane is delineated by the arrows. Staining of several endothelial cells for both defensin and Lp(a) is shown by the arrows.