Hydroxyl radical production in body fluids. Roles of metal ions, ascorbate and superoxide

Hydroxyl radical production, detected by ethylene formation from methional, has been investigated in plasma, lymph and synovial fluid. In the presence of added iron--EDTA, addition of either H2O2 or xanthine and xanthine oxidase gave rise to hydroxyl radical formation that in most cases was not superoxide-dependent. The ascorbate already present in the fluid appeared to participate in the reaction. In the absence of added catalyst, the reaction was hardly detectable, the rate being less than 5% of that observed with 1 microM-iron--EDTA added. This implies that the fluids had little if any capacity to catalyse hydroxyl radical production via this mechanism.