Assay System for the Effect of Prostaglandin E2 in the Determination of Polarized Cytokine Production

The activation of CD4⁺ T-cell subsets, Th1 and Th2, is one of the most important focuses of immunology. Th1 and Th2 are differentiated from naive T cells after antigenic stimulation by the influence of cytokines [interleukin 12 (IL-12)/interferon-γ (IFN-γ) in Th1 and IL-4/IL-13 in Th2] or costimulatory molecules (CD80/CD86) provided from antigen presenting cells (APC), and have several important immunological functions (1 ). Recently, several reports have shown that chemical mediators, such as prostaglandins (PG) and histamine, also affect Th1/Th2 cytokine production and Th differentiation (2 –7 ). PGE₂ is one of prostanoids produced by action of the enzyme cyclooxygenase (COX) on arachidonic acid. PGE₂ is mainly produced by APC: monocytes, macrophages, and dendritic cells in the immune system (2 ). PGE₂ has a suppressive effect on Th1-related cytokine productions such as IL-12 and IFN-γ by T cells, NK cells, and APCs, and an enhancing effect on Th2 development and activation.