This increase in mitochondrial ROS occurs without corresponding elevations in circulating proinflammatory cytokines, highlighting a potential early marker of immune system impairment in otherwise healthy individuals with MDD.[48] Notably, the long‐chain fatty acid eicosenoate impairs CD8+ T cell function in early HIV infection by increasing mitochondrial ROS and decreasing mitochondrial function, mediated through p53 induction. Here, CD8A is linked to HIV infectious disease.