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.