BACKGROUND: Iron continues to be linked to the pathogenesis of neurodegenerative disorders including HIV-1 associated neurocognitive disorders (HAND). People with HIV-1 who use opioids have a higher risk of developing HAND, and HIV-1 proteins and opioids disrupt endolysosome iron homeostasis, increase reactive oxygen species (ROS), and cause neural cell death. Endolysosomes are subcellular acidic organelles that regulate iron metabolism and redox homeostasis. HIV-1 gp120 and opioids induce endolysosome iron release, increasing cytosolic and in mitochondrial iron and ROS and inducing neurotoxicity. However, ROS represent only part of the reactive species interactome (RSI) and little is known about the extent to which HIV-1 proteins and opioids affect the RSI. RESULTS: In SH-SY5Y and U87MG cells, HIV-1 gp120, morphine, and iron supplementation de-acidified endolysosomes, decreased endolysosome Fe(2+) and H(2)S, and increased ROS, lipid peroxidation (LPO) and NO. These changes were accompanied by increased cytosolic and mitochondrial Fe(2+), ROS, LPO, and NO, decreased H(2)S, and increased cell death. All effects were blocked by the endolysosome-specific iron chelator deferoxamine. CONCLUSION: Endolysosome iron dyshomeostasis induced by HIV-1 gp120, morphine and iron supplementation disrupts inter-organellar iron signaling and RSI homeostasis. Targeting endolysosome iron may mitigate neurotoxicity in HAND and other disorders associated with iron overload and redox imbalance.