An antiproliferative bioassay for interleukin-4.

Abstract Inierleukin-4 (IL-4) is currently being used for therapeutic intervention in a wide range of malignant diseases as an antitumour agent. Although bioassays have been developed that measure the proliferative capacity of IL-4, none measure the antiproliferative activity of this molecule. We have developed a simple, sensitive bioassay for human IL-4 based on the ability of this cytokine to inhibit the proliferation of the human lung carcinoma line, CCL-185, an easy to maintain, cytokine independent, cell line. It is rapid, reproducible and sensitive, able to detect 2 pg/ml IL-4. The assay is completely unresponsive to all other interleukins from IL-2 to IL-12, to the colony stimulating factors and transforming growth factor beta and is 100-fold less sensitive to interferon-α tumour necrosis factor-α, IL-1β and IL-13. The assay can be made completely specific for IL-4 by including specific neutralizing antibodies for IL-4 and is suitable for the estimation of IL-4 in both plasma ard serum samples.