An opsonised microelectrode. Observation of the respiratory burst of a single human neutrophil

A 10 micron diameter gold microvoltammetric electrode, opsonised with human IgG, was used to study the respiratory burst of a single human neutrophil. The electrode oxidised superoxide produced near its surface by the neutrophil back to dioxygen. It is suggested that the current so detected is proportional to the rate of superoxide production by the NADPH oxidase of a single cell. In all cases the response consisted of a relatively rapid rise in current after cell addition, followed by a 2-phase decay. It is further suggested that this complex decay results from the production of superoxide being rate-limited initially by the NADPH concentration and later by the coupled metabolism of the hexose monophosphate shunt.