Interleukin-13 increases prostaglandin E₂ (PGE₂) production by normal human polymorphonuclear neutrophils by enhancing cyclooxygenase 2 (COX-2) gene expression

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 10⁶ 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 Fcγ receptor type 3 (FcγRIII). 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.