1. Departments of Biochemistry and Medicine, The Rogosin Kidney Center, Cornell University Medical College, 1300 York Avenue, New York, New York 10021, USA

Abstract

As natural killer (NK) cell activity is an essential constituent of host defence systems¹ and reactive oxygen intermediates participate in such defence^2–4, the effect of scavengers of oxygen radicals on NK cell activity was investigated. Hydroxyl radical (OH) scavengers⁵ (dimethyl sulphoxide (DMSO), thiourea, dimethylurea, tetramethylurea, benzoic acid, ethanol, methanol and ethylene glycol) inhibited NK cell activity. Catalase, a scavenger of H₂O₂, and Superoxide dismutase (SOD), a scavenger of O^-₂, either alone or in combination, did not inhibit NK cell activity. Inhibition of the lipoxygenase pathway of arachidonic acid metabolism, a potential source of cellular OH, with nordihydroguaiaretic acid⁶ and 5,8,11,14-eicosatetraynoic acid (ETYA)⁷ resulted in marked inhibition of NK cell activity. Inhibition of the cyclooxygenase pathway^7,8 with acetylsalicylic acid or indomethacin had minimal effects on NK cell activity. Taken together, these findings suggest that OH, possibly generated via the lipoxygenase pathway of arachidonic acid metabolism, is critical for NK cell cytotoxicity.