Ageing in Human Red Cells 237 



Crawford, Cutbush and Mollison, 1956). Notice that no ageing 

 in the ordinary sense has occurred since such cells are still 

 capable of surviving for three months after transfusion. 

 Even when red cells are stored at — 20° C the rate of deterio- 

 ration becomes very slow after the first six months (Crawford, 

 Cutbush and Mollison, 1955). 



Many of the changes that occur in red cells during storage 

 are reversible in vivo. For example, alterations in osmotic 

 fragility evidently depend to a large extent on the electrolyte 

 content of the storage medium. At + 4° C the normal active 

 cation transport across the red cell membrane is virtually 

 arrested and thus there is a slow shift towards osmotic 

 equilibrium. In media containing citrate this may lead to a 

 considerable loss of base from the red cells. These changes are 

 reversed after transfusion although it may take more than 

 four days for the reversal to be completed (Crawford and 

 Mollison, 1955). 



It has been shown that there is a rough parallel between the 

 decrease in ATP content of red cells and post-transfusion 

 survival (Rapoport, 1947). Finch and his co-workers (Gabrio, 

 Donohue and Finch, 1955) have shown that when adenosine 

 is added to blood, the ATP content of the cells is better main- 

 tained and viability is retained for a longer period. 



However there is considerable evidence that deterioration 

 during storage is very different from ageing in vivo. For 

 example, when red cells stored in A.C.D. at + 4° C for two 

 weeks are transfused it is found that about 10 per cent are 

 removed from the circulation within a few hours and the 

 remainder survive as well as fresh red cells. Note that it 

 cannot be the oldest red cells which have been lost since the 

 survival curve cuts the time axis at the same point as the 

 curve for fresh red cells (see Mollison, 1951). 



If red cells stored for three weeks are transfused to a subject, 

 then removed from the circulation, stored for three weeks and 

 again used for transfusion, they survive in the same way on 

 the second occasion (Gabrio, Stevens and Finch, 1954). 



Evidently, then, ageing in vivo and deterioration at + 4° C 



