Cryopreservation of human lymphocytes for sequential testing of immune competence.

Frozen stored lymphocytes are frequently used for sequential testing of immunological function in patients. The reliability of this system was investigated. By varying combinations of factors, it has been shown that lymphocyte samples, taken at different times and subsequently tested as a batch, give the most consistent results, the means of the various immune parameters measured on different sampling days in normal persons lying on straight lines parallel with the time axis. It is also shown that storage at -90 degrees C is equivalent to storage at -196.5% C.