CRYOPRESERVATION OF OSMOTICALLY FRAGILE Rhnull RED CELLS

To cryopreserve Rhnull red cells, we studied the osmotic fragility of the cells while seeking an effective method to protect the cells during cryopreservation. The coil planet centrifugation method, hypotonic swelling test and saponin-induced hemolysis test showed that Rhnull red cells were much more osmotically fragile than normal red cells. The osmotic fragility of Rhnull red cells was greater at lower pH levels. The recovery of frozen-thawed Rhnull red cells was approximately 68% and was about 20% lower than those of normal red cells. Autohemolysis on storage after thawing was also higher in Rhnull cells than in normal cells. The adenine-inosine-sucrose (AIS) solution was effective for increasing the osmotic resistance of Rhnull red cells. Incubation of Rhnull red cells with AIS solution before freezing resulted in approximately 80% of recovery in the freezing-thawing process. Sucrose had a marked protective effect against storage hemolysis of frozen-thawed red cells including Rhnull. These data indicate that AIS solution, which increased the osmotic resistance as well as the ATP and 2, 3-DPG levels of red cells, is useful for cryopreservation of rare bloods, particularly osmotically fragile red cells like Rhnull.