| Abstract: | A set of conditions is defined for freeze-storage of lymphocytes circulating in chronic lymphocytic leukaemia (CLL-lymphocytes) and in healthy individuals (normal lymphocytes). Isolated cells are frozen in culture medium containing 15 % serum and 8.3 % (v/v) dimethyl sulphoxide (DMSO) at a post-freezing cooling rate in the range 1.8-–3.4° per min to ?40° or below followed by immersion in liquid nitrogen, and thawed rapidly (ca. 400° per min) at 37°. This procedure induced consistently low mortalities (2–7%) in normal and CLL populations, uninfluenced by freeze-storage lasting up to 57 weeks, and was accompanied by large-scale destruction (67–100%, average 95 %) of residual isolated red cells. The lymphocytes classified as surviving cells by cytologic analysis could display partial loss of initial capacity for respiration but capacity for survival in short-term culture was retained. Brief reference is made to unchanged ultrastructural appearance of surviving cells. No pronounced differences were observed in the capacity of normal populations to transform under the influence of phytohaemagglutinin (PHA) as a result of freezing and thawing, but tests for altered proliferative capacity of transformed cells were hampered by culture conditions proving sub-optimal. Ultrasensitivity of CLL-lymphocytes in vitro to cytocidal action of colchicine — a property currently utilized for measurement of abnormal cell content of CLL-lymphocyte populations — was closely reproduced following freezing and thawing in experiments with 9 patients. |
