Priming study of human phagocytes oxidative burst by using flow cytometry.

In response to a variety of stimuli, e.g. pathogens, phagocytes release reactive oxygen species which are essential for bacterial killing and also potentiate inflammatory reactions. We have used flow cytometry measurements to study the priming process of phagocyte oxidative burst in whole blood, in order to avoid introducing artefacts due to the purification process and to stimulate the in vivo situation more closely. In these conditions, we examined the in vitro effects of proinflammatory cytokines (TNF-alpha, IL-1 alpha, IL-1 beta, IL-6, IL-8 and GM-CSF) on the PMN oxidative burst. We found that none of the cytokine tested directly activated the PMN oxidative burst. In contrast, TNF, GM-CSF and IL-8 strongly primed a subpopulation of PMN which produced large amounts of H2O2 in response to fMLP, suggesting that these cytokines may play a critical role in bactericidal killing in vivo. Furthermore, we reported a decreased H2O2 production by TNF or IL-8 primed PMN in HIV-infected patients. This impairment, which correlated with the clinical stage of the disease, could contribute to the increased susceptibility to bacterial infections in HIV-infected patients. In addition, we reported the case of a child with severe recurrent infections due to intracellular microorganisms which could be related to an impairment of the phagocyte priming process of the oxidative burst [corrected].