The Use of Directly Frozen Cells in LDA Assay

Abstract

A method of direct freezing is described which requires a cryoprotective medium consisting of human AB serum and DMSO, an ultra-low temperature freezer and a liquid-nitrogen refrigerator. Fresh and directly frozen cells were compared in the LDA assay. Direct freezing is quite reliable for normal lymphocytes, PHA transformed lymphocytes or leukaemic blasts used as targets. However, a controlled freezing procedure may be necessary to preserve the effector cell activity.

Frozen Lymphocyte Pools as Technical and Reference Controls for Lymphocyte Transformation

“…It has been shown in a number of laboratories that lymphocytes frozen in a controlled manner and stored at low temperatures retain many of the functional parameters of fresh lymphocytes for considerable periods of time, and exhibit these in a reproducible manner (Golub et al 1975, Werner et al 1975, Birkeland 1976. While individuals' lymphocytes stored in this way may be used as controls for lymphocyte transformation, lymphocytes obtained from different individuals andfor at different times show considerably different magnitudes of responses, and the numbers of lymphocytes which may be obtained from an individual at any one time are relatively small.…”