PMN functions during chronic infection of rhesus macaques with the pathogenic SIVmac251 strain or the attenuated SIVΔ nef strain. Basal CD11b expression on the PMN surface (A) and basal ROS production (B) were studied in whole blood samples. Results are expressed as Mean Fluorescence Intensity (MFI). Data are reported as means ± SEM. Comparisons were based on ANOVA and Tukey's posthoc test, using Prism 3.0 software. * Significantly different from healthy controls (SIV- group) (p < 0.05); † Significantly different from SIVΔnef macaques (p < 0.05); †† Significantly different from SIV+ SP (p < 0.05).