Measurement of interleukin-13.

This unit describes two protocols that can be used to quantitate interleukin-13 (IL-13). The enzyme-linked immunosorbent assay (ELISA) has the advantage of being highly specific for human IL-13 and does not recognize other cytokines present in the sample. A bioassay is also presented based on the ability of IL-13 to stimulate the growth of the B9 plasmacytoma cell line. The bioassay method can be used to detect both mouse and human IL-13. B9 cells are dependent on IL-6 for growth and will also respond to IL-4. Thus, although B9 cells can readily be used to quantify IL-13 in the absence of other cytokines, neutralizing antibodies must be incorporated into the bioassay when other cytokines are present in the sample.