Cryopreserved human cultured T cells as responder cells for the quantitative measurement of interleukin-2: improvement of the assay.

Large batches of human cultured T cells (CTC) were cryopreserved for later use as responder cells in a proliferation assay for measurement of interleukin (IL)-2 activity. Cryopreservation of CTC could be carried out without considerable loss in viability and cryopreserved and fresh cells showed equally good responses to IL-2. The conditions of IL-2-dependent CTC growth were analyzed, which led to a better evaluation of test results, and had important implications for the calculation of relative IL-2 activity. The repeated use of the same batch of cryopreserved CTC reduced test variability and provided an assay system that allows reliable and reproducible measurement of human IL-2 activity.