UNIT 6.13 Measurement of Mouse and Human Interleukin 9

This unit describes two proliferation assays to detect or quantitate human and murine interleukin 9 (IL-9). The first is based on the ability of IL-9 to stimulate the proliferation of the TS1h9RA3 cell line, a murine IL-9-dependent cell line transfected with the human IL-9 receptor. An alternate protocol is based on the ability of IL-9 to stimulate the proliferation of the human megakaryoblastic leukemia cell line, M-O7e. M-O7e cells depend on either human IL-3 or granulocyte/macrophage colony-stimulating factor (GM-CSF) for growth, although other cytokines including IL-2, -4, -6, and -9 and steel factor are also weakly mitogenic (relative to IL-3 and GM-CSF). Thus, although M-O7e cells can readily be used to quantitate levels of IL-9 in the absence of other cytokines, analysis in the presence of complex mixtures of cytokines (e.g., natural sources) requires the use of specific antibodies against IL-9 and the other cytokines, as described in this unit.