Measurement of interleukin-17.

Upon antigenic stimulation, naive CD4+ T cells undergo proliferation and differentiate into cytokine-producing T helper (T(H)) effector cells. T(H)1 cells secrete effector cytokine IFN-gamma and regulate cell-mediated immunity, whereas T(H)2 cells produce IL-4, IL-5, and IL-13 cytokines, and mediate immunity against extracellular pathogens and allergic reactions. Recent studies have identified a novel T(H) subset, called T(H)17, TH(IL-17), or inflammatory T(H) (THi) cells, characterized by the production of a proinflammatory cytokine, IL-17, and regulating inflammatory responses. In this unit, we describe the protocols for the differentiation of mouse IL-17-expressing T cells in vitro, detection of IL-17-expressing T cells by intracellular cytokine staining, and measurement of IL-17 secretion in culture supernatants by ELISA. Generation of IL-17-expressing T cells in vitro under defined culture conditions allows investigation of their differentiation regulation. Detection of IL-17 in cell culture and tissue samples helps in monitoring inflammatory diseases and determining efficacy of therapeutic interventions. (c) 2007 by John Wiley & Sons, Inc.