[Cryopreservation of lymphocytes using polyethylene glycols of high polymerization grade (author's transl)].

Human peripheral lymphocytes and mouse spleen cells were frozen under controlled rates in the presence of polyethylene glycols (PEG) of high polymerization grade, stored in liquid nitrogen and tested, following thawing and mitogen-stimulation, for their capacity to incorporate 3H-thymidine and to form colonies in soft agar. We found that human lymphocytes, frozen with 10% PEG 20,000 and PHA-stimulated afterwards, showed an 8 fold higher incorporation rate versus 7.5% dimethylsulfoxide, whilst colony growth was unaffected. The potentiating effect by PEG was also seen with mouse spleen cells. PHA-prestimulated human lymphocytes also revealed an increased incorporation rate. Due to their lower toxicity the PEG offer, as cryoprotecting agents, a useful alternative to dimethylsulfoxide.