Zaitsu_2000_Blood_96_601

Interleukin (IL)-4, IL-10, and IL-13, Th2 cell-derived cytokines, play major roles in the pathophysiology of allergic diseases. These cytokines up-regulate or down-regulate the production of arachidonic acid metabolites. In this study, we have investigated the effect of IL-4, IL-10, IL-13, and other cytokines on A23187-stimulated synthesis of leukotriene (LT) B(4) in human polymorphonuclear leukocytes (PMNs). Production of LTB(4) was measured by specific radioimmunoassay and high performance liquid chromatography. Messenger RNA (mRNA) expression of cytosolic phospholipase A(2) (cPLA(2)), 5-lipoxygenase (5-LO), and LTA(4) hydrolase, which were involved in the synthesis of LTB(4), was determined by reverse transcription-polymerase chain reaction and Northern blot analysis. Protein synthesis of their enzymes was determined by Western blot analysis. IL-4 and IL-13 enhanced A23187-stimulated LTB(4) synthesis and increased mRNA expression and protein synthesis of LTA(4) hydrolase, but not those of cPLA(2) or 5-LO. These results indicate that IL-4 and IL-13 transcriptionally or post-transcriptionally up-regulate the synthesis of LTB(4), a potent chemotactic factor to PMNs, at the enzyme level of LTA(4) hydrolase, and this up-regulation mechanism may participate in the development of allergic inflammation. (Blood. 2000;96:601-609)