The Effect of Acetaminophen on the Neutrophil Oxidative Burst

Abstract

The dihydrorhodamine (DHR) assay is used to quantify the neutrophil oxidative burst, which is reduced in primary immunodeficiencies with defective neutrophil function, such as chronic granulomatous disease (CGD) or RAC2 deficiency. Although there are reports of reduced neutrophil oxidative burst after in vitro neutrophil exposure to acetaminophen, there are no systematic studies that address whether therapeutic doses of acetaminophen impair the neutrophil oxidative burst. We demonstrate that the neutrophil oxidative index (NOI) is dramatically impaired by acetaminophen in healthy human subjects. This effect which peaked 2 hours after administration dissipated within 24 hours and correlated with inhibition of myeloperoxidase (MPO) activity. Retrospective analysis of 195 hospitalized patients without CGD or RAC2 revealed an abnormal DHR results nearly half of the time (44.8%) when patients had DHR testing within four hours of acetaminophen exposure. No similar effect was seen with ibuprofen, steroids or lidocaine. This data shows that to avoid falsely abnormal testing for CGD, patients should be advised to avoid acetaminophen for at least 24 hours prior to DHR testing.