Effects of interleukin-13 on human neutrophil functions

It was recently shown that interleukin-13 (IL-13) induces the expression and release of the IL-I decoy receptor (type II) in human neutrophils along with the production of the IL-1 receptor antagonist, In the present study we focused on further studying the modulatory effects of IL-13 on these cells, We found that recombinant human IL-13 (rhIL-13) induces cellular morphological changes in neutrophils that are typical of activated cells, Furthermore, rhIL-13 was shown to increase tyrosine phosphorylation of several neutrophil proteins, We also demonstrate that this cytokine stimulates de novo RNA synthesis in a concentration-dependent fashion as measured by [5-H-3]uridine incorporation and that rhIL-13 induces the synthesis of several neutrophil proteins according to high-resolution two-dimensional gel electrophoresis of metabolically [S-35]-labeled cells. We observed that the IL-8 levels in the external milieu of IL-13-stimulated cells was almost fivefold increased when compared with control cells, Finally, we observed that rhIL-13 has no significant effect on phagocytosis and apoptosis, Taken together, our results demonstrate that IL-13 is a modulator of several human neutrophil functions, This leads us to conclude that the modulatory role of IL-13 on human neutrophils, a potentially important anti-inflammatory cytokine, is more complex than previously believed, Furthermore, because we show that the synthesis of several as yet unidentified proteins was up-regulated by IL-13, our findings open new avenues of research on the effects of this cytokine on human neutrophils.