Objective: To investigate whether interleukin-13 (IL-13) can affect arachidonic acid metabolism and phagocytic activity of normal human polymorphonuclear neutrophils (PMN).
Methods: Normal human PMN (1 x 10(6) cells/ml) were incubated with different concentrations of IL-13 (0.1-10 ng/ml) for a variety of times (30-120 min). Phagocytosis and intracellular cyclooxygenase-2 (COX-2) were detected by flow cytometry. The expression of COX-1 and COX-2 mRNA was detected by RT-PCR. The concentration of PGE2 in the PMN cultured supernatants was determined by EIA.
Results: We found that IL-13 at an optimal concentration of 1 ng/ml significantly enhanced COX-2 gene expression and PGE2 production (121.57 +/- 22.17 pg/ml in IL-13 stimulation vs. 73.16 +/- 11.72 pg/ml in controls) by PMN. In addition, IL-13 stimulated PMN phagocytosis via increased complement receptor type 1 (CR1) and type 3 (CR3), but not IgG Fcgamma receptor type 3 (FcgammaRIII). The cytoplasmic neutral esterase activity of PMN was also enhanced by IL-13 stimulation for 24 h.
Conclusions: These results suggest that IL-13 can stimulate PMN and modulates the inflammatory reactions via the cyclooxygenase pathway.