Direct measurement of reactive oxygen species in leukocytes during hemodialysis therapy

Objectives: Both chronic kidney disease (CKD) and hemodialysis (HD) are reported to elevate oxidative stress. Available evidence for oxidative stress is indirect measurement of oxidative stress as accumulation of byproducts by reactive oxygen species (ROS). We aimed to examine the effect of CKD and HD on ROS levels in circulating leukocytes and to compare those with conventional oxidative stress marker, F2-isoprostane, in HD patients. Methods: Using flowcytometry techniques, ROS levels in circulating leukocytes can be directly measured in 16 HD patients and 12 healthy volunteers. We also measured circulating F2-isoprostanes levels in both groups. Results: HD patients demonstrated a significant increase in serum levels of F2-isoprostanes. The direct measurement of ROS levels in leukocytes showed increase in HD patients compared to the control; 1.91-fold in polymorphonuclear leukocytes (PMN), 1.06-fold in lymphocytes, and 1.35-fold in monocytes. Significant difference between the two groups could be observed only in PMN. The ROS levels in all three fractions of leukocytes showed negative correlations with serum F2-isoprostane levels but the ROS levels only in PMN showed significant correlation (r2 = 0.774, P = 0.001). Conclusions: Our results indicate that direct measurement of the ROS levels in circulating leukocytes by flowcytometry is a useful method to examine oxidative stress during HD procedure. The ROS levels in circulating leukocytes showed negative correlation with serum F2-isoprostane levels.