Table 1: Reactive oxygen species (ROS) levels, superoxide dismutase (SOD) activity and rates of cell death in unstimulated leukocytes from young and elderly individuals.

Neutrophils Lymphocytes   Young Aged Young Aged ROS levels + +++ + ++ SOD activity ++ + ++ + Rate of cell death + ++ + ++

The levels of ROS, SOD activity, and rate of cell death were all classified on a scale of + (indicating lowest level, activity or rate) to +++ (indicating highest intensity level, activity or rate). Data were taken from Espino et al. 2010 [49].