Receptor and non-receptor mediated formation of superoxide anion and hydrogen peroxide in neutrophils of intensive care patients.

Generation of reactive oxygen intermediates (ROI) has been implicated in tissue damage in a variety of disease states including sepsis and trauma. On the other hand, generation of ROI in polymorphonuclear granulocytes (PMN) presents a crucial element in the defence of the host against invading microorganisms. In the present study we investigated the generation of superoxide anions (O2-) and hydrogen peroxide (H2O2) by neutrophils (PMN)5 of 17 critically ill patients treated at a intensive care unit (ICU) after polytrauma (n = 6), heart operation (n = 6) or during septic shock (n = 5) using flow cytometry. O2- production of PMN from ICU patients was significantly lower (p < 0.01) than that in healthy volunteers (HV) during non-receptor mediated stimulation with phorbol-myristate-acetate (PMA) but higher (p < 0.001) during receptor mediated stimulation with formylmethionine-leucine-phenylalanine (FMLP). H2O2 generation of PMN from ICU patients was increased after stimulation with FMLP (p < 0.01) and remained unchanged after stimulation with PMA. Patients in septic shock had lower O2(-)-generation of PMN than did injured patients and patients after heart operations. We conclude that receptor mediated formation of O2- and H2O2 is stimulated in ICU patients. However, in patients in septic shock O2(-)-generation decreases, which potentially might contribute to the immunoparalysis present in septic shock.