THE INFLUENCE OF CRYOPRESERVATION ON CYTOKINE PRODUCTION BY HUMAN T-LYMPHOCYTES

Human T lymphocytes isolated from peripheral blood were cryopreserved at - 196 degrees C for different periods of 3, 14, 21, 35, and 50 days . Viability and cytokine-producing activity of T cells were examined b efore and after cryopreservation. A high recovery (90 +/- 1%) of viabl e T cells was obtained at each frozen period, indicating that a 10% lo ss of cells was due to the freezing process rather than the duration o f cryopreservation. There was no difference in cell cycle distribution between PHA-treated fresh and frozen lymphocytes. Resting human T cel ls produced little or no cytokine. After stimulation of fresh T cells with PHA, an apparent increase in cytokine production was noted in IL- 2 (35. +/- 8.3 pg/ml), IL-6 (1280.4 +/- 64.7 pg/ml), tumor necrosis fa ctor-alpha (874.3 +/- 71.7 pg/ml), interferon-gamma (58.9 +/- 2.2 pg/m l), and granulocyte macrophage-colony-stimulating factor (59.5 +/- 4.4 colonies/5 x 10(4) bone marrow cells). Compared with PHA-activated fr esh T cells, all the above cytokines did not diminish in their levels in conditioned medium from PHA-treated frozen T cells thawed at each s torage period, suggesting that cryopreservation could well retain the cytokine-producing activity of human T lymphocytes. In addition, our r esults also revealed that cryopreservation rendered T lymphocytes more responsive to PHA in IL-2 production than fresh T cells, (C) 1998 Aca demic Press.