An enzyme-immunoassay for human interleukin-2.

A highly sensitive enzyme-immunoassay (EIA) for human interleukin-2 (IL-2) has been established. The assay is based on a sandwich method that uses two kinds of anti-IL-2 antibodies raised against Escherichia coli-derived recombinant IL-2 (rIL-2). An affinity-purified-anti-IL-2 goat IgG was used as the first antibody and the Fab' fragment of an affinity-purified-anti-IL-2 rabbit IgG was used as the second antibody after being coupled with horseradish peroxidase (HRP). As little as 30 pg/ml of IL-2 was detected by the EIA, indicating that this method was about 100 times more sensitive than the bioassay using an IL-2-dependent murine natural killer cell line, NKC3. There was a good correlation between the EIA and the bioassay (r = 0.998).