DETERMINATION OF INTERLEUKIN-2 ACTIVITY BY A NEW FLUOROMETRIC METHOD

Interleukin 2 activity is usually determined by a proliferation assay using an IL-2-dependent cell line. Tritiated thymidine incorporation d uring DNA synthesis is a suitable method for this purpose, but its mai n drawback is the use of radioactive isotopes. We describe the use of Alamar Blue, a new fluorogenic growth indicator, for the measurement o f interleukin 2 activity in microtitration plates. This assay is sensi tive and economical. The lower limit of detection is about 400 cells p er well with an intra-assay coefficient of variation of about 5 percen t.