Dimethylsulfoxide (DMSO), a hydroxyl radical scavenger, exerted a dose dependent inhibition on the luminol and lucigenin-enhanced chemiluminiscent responses of human neutrophils activated with soluble and particulate stimulants. DMSO inhibition of the luminol chemiluminescence induced by calcium ionophore A23187 was probably due to ^.OH scavenging, whereas inhibition of the lucigenin chemiluminiscence suggested DMSO negatively affects the NADPH-dependent membrane oxidase of neutrophils. In agreement with this, DMSO moderately inhibited O₂ consumption in PMN suspensions stimulated with chemotactic peptide and opsonized zymosan. DMSO inhibition of chemotactic peptide and opsonized zymosan-induced luminol chemiluminescence was observed only when added before or in conjunction with stimulants, whereas A23187-induced chemiluminescence was inhibited by DMSO regardless of time of addition. Washing of DMSO-treated PMN resulted in increased luminol enhanced chemiluminescence in response to chemotactic peptide and opsonized zymosan. This is consistent with the idea that DMSO may be interfering with activation of the membrane subunits of the oxidase by translocation and docking of the cytoplasmic, regulatory subunits. These data imply that DMSO inhibits neutrophil chemiluminescence both by ^.OH scavenging and interfering with oxidase activation.

Dimethylsulfoxide; chemiluminiscent; luminol; lucigenin; neutrophils