A fluorometric assay for determining cell growth in lymphocyte proliferation and lymphokine assays

A microplate method for assessing cell growth and viability based on the hydrolysis of fluorogenic substrates by cell esterases has been investigated. Living cells incubated with fluorescein diacetate or 4-methylumbelliferyl heptanoate generate a fluorescent product which is proportional to the number of cells. This can be used as a simple and economical readout for various bioassays such as, for example, the assessment of IL-2 and IL-3 on factor-dependent cell lines, and on antigen- and mitogen-stimulated proliferation of lymphocytes. This fluorometric assay has similar sensitivity to the measurement of [3H]thymidine uptake and greater sensitivity than standard colorimetric assays. Incubation with MUH for a period of 30-60 min at 22 degrees C is adequate.