The effect of osmotic stress on the function of the human granulocyte

Clinical investigations have shown that the transfusion of human granulocytes can protect the neutropenic patient against acute bacterial infection. The increasing utilization of granulocyte therapy plus an inability to store these cells in liquid media have created a requirement for a cryopreservation technique. However, the cryopreservation of human granulocytes has proven quite difficult to achieve. It is likely that one of the contributing factors is the lability of these cells under osmotic stress. The purpose of this paper was to precisely define the osmotic tolerance limits of the human granulocyte and thereby provide guidelines for the laboratory manipulation of this cell. To accomplish this, cells were exposed to hypertonic or hypotonic media and then tested for viability under isotonic conditions. Function tests included phagocytosis of particles, bacterial killing, migration in the Boyden chamber, and migration under agarose. The experiments revealed that granulocytes will tolerate a narrow range of osmolalities extending from 200 mOsm to 600-700 mOsm. The osmotic damage occurs in less than 30 seconds and appears to be irreversible. The hypertonic limit of the cell cannot be extended by reducing the temperature to 0 degrees C during the osmotic challenge.