In vitro reactivity to concanavalin A of bovine lymphocytes after cryopreservation.

Cryopreservation of bovine peripheral lymphocytes and its effect on the in vitro response to concanavalin A tested in a microculture system is described. Using DMSO as cryoprotectant in the medium, the cells were cooled to -30 degrees C at 1.3 degrees C/minute and further to -80 degrees C at 6 degrees C/minute and then rapidly to -196 degrees C by dropping in liquid nitrogen. The cells were recovered by rapid thawing in water at 30-35 degrees C and washed twice before use in the stimulation test. Ten percent DMSO had a much better protective effect than 5%; addition of 25% fetal bovine serum to the freezing had no favourable effect. In most of the 16 animals used in the experiments the frozen lymphocytes gave the same or a higher response to Con A than those kept in the DMSO containing medium at 4 degrees C for two hours. The responses of the frozen cells were comparable to those of fresh lymphocytes (kept at 4 degrees C for two hours in medium without DMSO).