The variable effect of cryopreservation on peripheral blood mononuclear populations

Peripheral blood mononuclear cells (PBMC) were cryopreserved using 0.5 degree C/min or 1 degree C/min cooling rates. Following thawing they were evaluated by cell surface marker analysis and mitogen reactivity. T cells, B cells and monocytes were preserved when cooled at 0.5 degree C/min. B cells and monocytes were preserved when cooled at 1 degree C/min but T cell numbers decreased. Similarly FC gamma bearing T cells were preserved when cooled at 0.5 degree C/min but when cooled at 1 degree C/min they were decreased. Following thawing, incubation of PBMC with histamine induced or activated FC gamma bearing T cells. PBMC cooled at 0.5 degree C/min showed retention of nonspecific suppressor T cell activity in early cultures (96 hr) which could be induced and activated in late cultures (144 hr) whereas at 1 degree C/min nonspecific suppressor T cells were not preserved but could be induced and activated in late cultures (144 hr). Prostaglandin secreting monocytes retained functional activity independent of the cooling rates tested. Different cooling rates have variable effects on suppressor elements.