Figure 4

Plasma IL-8 levels and their correlations with measures of atherosclerotic lesion severity. (a) Levels of plasma IL-8 were measured 4 weeks before virus inoculation of the SIV-positive group, 4 weeks after virus inoculation of the SIV-positive group, and at the time of killing. Circulating IL-8 levels did not differ significantly between groups at any time point. SIV positive, animals assigned to SIV-infected group; SIV negative, animals assigned to uninfected control group. (b) A small subset of animals from both the SIV-negative and the SIV-positive groups demonstrated baseline IL-8 levels substantially lower than the mean. SIV positive, animals assigned to SIV-infected group; SIV negative, animals assigned to uninfected control group. (c) Atherosclerotic plaque cross-sectional area at the carotid bifurcation showed a significant inverse correlation with baseline plasma IL-8 levels, such that more extensive carotid plaques at necropsy were associated with lower baseline levels of IL-8 (P<0.04, R=−0.619). (d) Atherosclerotic plaque cross-sectional area at the common iliac bifurcation showed a significant inverse correlation with baseline plasma IL-8 levels, such that more extensive plaques at necropsy were associated with lower baseline levels of IL-8 (P<0.02, R=−0.685). (e) Extent of CD68 immunolabeling in the most severely affected vessel for each animal showed a significant inverse correlation with baseline plasma IL-8 levels, such that lower baseline plasma IL-8 levels were associated with more extensive CD68+ signal (P<0.01, R=−0.775).