The immunocompetence of residual lymphocytes at various stages of red cell cryopreservation with 40% w/v glycerol in an ionic medium at -80 C.

Potentially immunocompetent cells have been found in washed liquid-stored red blood cells, in washed liquid-stored red blood cells to which a 40% W/V glycerol concentration was added, and in washed red blood cells freeze-preserved with 40% W/V glycerol at -80 C. A glycerol concentration of 40% W/V in an ionic medium, in addition to its cryoprotective effect on red blood cells, has a damaging effect on leukocytes. The freeze-thaw-wash process appears to produce the most damage to leukocytes and the remaining lymphocytes can be categorized into two groups: one that is capable of responding to phytohemagglutinin (PHA), and one that is not. Our study confirmed the presence of PHA-responsive lymphocytes in red blood cells freeze-preserved with 40% W/V glycerol in an ionic medium at -80 C. Although the relative proportions of these cells were variable and the results of the study somewhat erratic, we continue to recommend that liquid-preserved and freeze-preserved red blood cells be irradiated before transfusion to patients in whom graft-versus-host disease is a possible complication.