Figure 1

Atherosclerotic plaque character. (a) Thoracic aorta, SIV-negative animal. Stratified accumulations of intimal foam cells with smooth muscle proliferation, low numbers of lymphocytes, small pools of extracellular lipid, and an early deep focus of necrosis containing scant granular mineral (hematoxylin and eosin). (b) Summary of atherosclerotic plaque cross-sectional area findings at carotid bifurcation, cranial abdominal aorta, and common iliac bifurcation for each animal as a function of SIV infection status. Each of the three vessels from any single animal is represented by a single color. SIV-infected animals as a group showed a modest trend toward increased early plaque development, but one animal from each group demonstrated vessels with substantially greater plaque burdens than those of other animals in the cohort. (c) Carotid bifurcation, SIV-positive animal. CD3 immunolabeled cells are present in moderate numbers within the mild atherosclerotic lesion in the intima, but also extend deep into the media as part of an intense mixed inflammatory focus (CD3 immunohistochemistry with DAB chromogen and Mayer's hematoxylin counterstain). (d) Numbers of cells immunolabeling for CD3 within carotid plaques correlated strongly with plaque cross-sectional area (P<0.001, R=0.890). (e) Carotid bifurcation, SIV-positive animal. CD68 immunolabeled cells constitute the primary population within the intimal lesion, but also extend deep into the media as part of an intense mixed inflammatory focus. (CD68 immunohistochemistry with DAB chromogen and Mayer's hematoxylin counterstain.) (f) CD68 signal area within carotid plaques correlated strongly with plaque cross-sectional area (P<0.001, R=0.940).