A modified assay for interleukin-1 (IL-1).

A simple and reliable biological assay for interleukin-1 (IL-1) was developed, based on the production of interleukin-2 (IL-2) from the EL-4 murine T-cell lymphoma cell line, in the presence of 2-5 X 10(-7) M calcium ionophore A23187. The assay was generally performed in 2 stages ((a) IL-1-dependent IL-2 production, and (b) IL-2 assay) and took 36-48 h to complete. This assay was found to be 10-25 times more sensitive than the mouse thymus cell assay, was not sensitive to the presence of bacterial endotoxin, and had the advantage of not requiring the use of animal tissue as a source of cells. The assay was used in our laboratory to detect human, mouse, rat, and rabbit IL-1 of all isoelectric-point types.