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- Title
TNFα-induced activation of eosinophil oxidative metabolism and morphology -- Comparison with IL-5.
- Authors
Zeck-Kapp, Cabriele; Czech, Wolfgang; Kapp, Alexander
- Abstract
Human dermal mast cells are capable of releasing cytokines, particularly preformed TNFα, upon appropriate stimulation. Mast cell activation in vivo was shown to be associated with an influx and activation of inflammatory cells, initially PMN (polymorphonuclear neutrophilic granulocytes) then eosinophils. In order to learn more about the mechanisms by which TNFα is capable of activating eosinophils, in the present study the effect of TNFα on morphology and function of highly purified normal eosinophils ( ≥ 95%) was examined. As estimated by transmission and scanning electron microscopy, TNFα-stimulated eosinophils appeared to be strictly adherent and flattened exhibiting a characteristic "hemispheric" shape. TNFα induced a dose-dependent, long-lasting production of reactive oxygen species as measured by lucigenin-dependent chemiluminescence (CL), even at a concentration of 0.001 U/mI. The maximal response upon stimulation with TNFα, however, was significantly lower than optimal effects induced by IL-5. TNFα- induced responses were completely inhibited by cytochalasin B and staurosporin, and partially blocked by pertussis toxin. Separation of eosinophils by discontinuous density gradients revealed the existence of at least two hypodense eosinophil populations with a distinct susceptibility to stimulation with TNFα. Based on functional assay systems, in contrast to a significant extracellular, only a small intracellular H[SUB2]O[SUB2] production was detected. Accordingly, H[SUB2]O[SUB2] production, detected by an ultrastructural technique, was observed only on the outer surface of the plasma membrane in the contact zones in between adjacent cells.
- Subjects
EOSINOPHILS; GRANULOCYTES; CYTOKINES; INTERLEUKIN-5; REACTIVE oxygen species; HYDROGEN peroxide; ELECTRON microscopy
- Publication
Experimental Dermatology, 1994, Vol 3, Issue 4, p176
- ISSN
0906-6705
- Publication type
Article
- DOI
10.1111/j.1600-0625.1994.tb00275.x