ISSN:
1432-069X
Keywords:
Granulocyte
;
Cytokines
;
Superoxide
;
Oxygen radicals
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary As shown previously monocytes upon stimulation with bacterial lipopolysaccharides (LPS) release granulocyte-activating mediator(s) (M-GRAM) which induced a long-lasting chemiluminescence (CL) response in human granulocytes. M-GRAM could be separated from interleukin-1α and β, interleukin-2, interferon α and γ, granulocyte colony stimulating factor (G-CSF) and macrophage colony stimulating factor (M-CSF), since these cytokines were shown to be unable to induce a significant CL response. In contrast, granulocyte macrophage colony stimulating factor (GM-CSF) and particularly tumor necrosis factor (TNF) are important triggers of the oxidative burst and they are capable of inducing a CL response. TNF activity but not lymphotoxin (LT) activity could be demonstrated in M-GRAM samples. A polyclonal rabbit IgG as well as a monoclonal antibody to recombinant human TNF which neutralized the TNF activity in M-GRAM preparations did not substantially block the CL signal. Furthermore, M-GRAM-induced CL response was not significantly inhibited by a polyclonal calf antiserum to human recombinant GM-CSF. For further functional characterization of M-GRAM-induced granulocyte activation different assays were performed in order to compare GM-CSF and TNF: (a) SOD-inhibitable cytochrome C-reduction (.O2 -); (b) horse radish peroxidase-mediated oxidation of phenol red (H2O2); (c) the release of peroxidase; (d) ultrastructural detection of hydrogen peroxide production; and (e) scanning and transmission electron microscopy (SEM and TEM). Significant release of .O2 - was induced by M-GRAM, TNF, and GM-CSF, whereas H2O2 production was significantly stimulated only by M-GRAM and TNF, as shown by functional and ultrastructural assays. In contrast, only M-GRAM was able to induce significant release of peroxidase. Granulocyte activation could be visualized by SEM and TEM. Upon stimulation with M-GRAM polymorphonuclear neutrophilic granulocytes (PMN) showed an increased adherence to the substratum, developing an increased number of intracytoplasmic vacuoles and short filopodia, whereby the morphological pattern was different from that induced by GM-CSF and TNF. Based on our results we suggest that M-GRAM activity is mediated, in addition to TNF, by a possible new cytokine which is capable to specifically activate granulocytes turning them into scavengers of invading microbes and parasites.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00426612
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