Effects of cryopreservation on human lymphocyte functions: comparison of programmed freezing method by a direct control system with a mechanical freezing method.

The effects of cryopreservation with a new-type programmed freezer (TNP-82) were examined on natural killer (NK) activity and cell recovery of lymphocytes. This instrument is controlled by a sensor which directly detects the temperature in the samples, enabling easy setting of the temperature curve. Comparing results obtained by the new method to those from a less sophisticated mechanical method, cell recovery after cryopreservation was improved (95.3%) in the new compared to the older (about 80%) method. Furthermore, NK activity, percentage of Leu7+ cells and other lymphocyte functions were unaltered.