Modulation of granulocyte oxidative response by recombinant interferon alpha 2 and gamma

Effect of interferon-alpha on production of reactive oxygen species by human neutrophils

In order to examine that the effects of interferon alpha (IFN-alpha) on the production of reactive oxygen species from human neutrophils, we investigated in vitro effects of IFN-alpha on neutrophil chemiluminescence responses. Human neutrophils were incubated with 0-1 x 10(5) IU/mL IFN-alpha for 10-60 min just before stimulation with opsonized zymosan and phorbol 12-myristate 13-acetate. Luminol-dependent (LmCL) and lucigenin-dependent (LgCL) chemiluminescence responses were measured using a Lumi Box H-1000. The LmCL response was inhibited by pre-incubation with high concentrations of IFN-alpha (more than 1 x 10(4) IU/mL). In contrast, LgCL response was increased when neutrophils were pre-incubated with high concentration of IFN-alpha. Effects of pre-incubation of IFN-alpha were similar between CL responses stimulated with OZ and PMA. The increase of LgCL might be due to the inhibitory effect of IFN-alpha on myeloperoxidase degranulation, in view of the decreased LmCL responses.

Activation of human polymorphonuclear neutrophilic granulocytes by immuno-modulating cytokines: an ultrastructural study

Activated granulocytes play an important role in the propagation of inflammatory reactions and are capable of mediating tissue damage by the release of reactive oxygen species and lysosomal contents. Cytokines produced by immunocompetent and other cells were recently suggested to influence granulocyte functions. Therefore, in the present study, we investigated the effect of relevant immuno-modulating cytokines on isolated human granulocytes by ultrastructural criteria: scanning and transmission electron microscopy, ultrastructural detection of H2O2. The following recombinant human cytokines were tested: tumor necrosis factor (TNF), lymphotoxin (LT), GM-CSF, M-CSF, G-CSF, interleukin 1 (IL 1) alpha and beta, IL 2, IL 3, IL 4, IL 6, interferon (IFN)-alpha and gamma. Only TNF, LT, GM-CSF and IL 3 (at high concentrations) induced significant morphological changes (increased adherence to plastic layers, typical polarization, development of intracellular vesicles) and production of H2O2. None of the other cytokines tested induced any detectable effect on isolated granulocytes even at unphysiological concentrations. The results clearly demonstrate that only certain cytokines are capable of influencing granulocytes. Release of these mediators represents a specific signal for granulocyte activation in inflammatory disease states.