Ageing in Human Red Cells 235 



It seems probable that what red cells cannot do is to 

 synthesize enzymes. It is known that the cholinesterase 

 activity of reticulocytes is two to three times higher than that 

 of mature cells (Sabine, 1951). It has also been shown that 

 the cholinesterase activity of rat red cells increases following 

 haemorrhage and then gradually declines (Pritchard, 1949). 

 Recently, Allison and Burn (1955) have shown that the 

 cholinesterase and catalase content of transfused red cells 

 diminishes progressively with time. 



It thus seems very likely that the fuel of the red cell which 

 becomes exhausted with time is its content of enzymes. 

 When the enzyme content falls to a certain level, the active 

 processes upon which the integrity of the red cell depends 

 cease and the red cell disintegrates. It is known that the red 

 cell derives most of its energy from anaerobic glycolysis. 

 However, it is not known how failure of the supply of energy 

 determines the death of the red cell. 



One possible experimental approach to this problem would 

 be to treat red cells with various agents which might enhance 

 or destroy a particular enzyme system, and then study the 

 effect on the survival in vivo of the treated cells. This possi- 

 bility is suggested by the observation that when red cells are 

 treated with more than a certain amount of sodium chromate 

 their survival is interfered with. When a certain dose is added 

 the red cells at first survive normally, but then after about 

 14 days in the circulation the death rate suddenly rises and 

 within 10 days almost all are gone (Hughes Jones and Mollison, 

 1956). A study of the way in which this premature ageing 

 of red cells is brought about might be very rewarding. It is 

 possible that the damage is not due directly to chromium but 

 rather to oxidation. When sodium chromate is added to red 

 cells mixed with A.C.D. in amounts of the order of 50 (xg./ml., 

 sufficient methaemoglobin is formed to turn the suspension of 

 red cells brown. Although the presence of methaemoglobin 

 in red cells in congenital methaemoglobinaemia does not alter 

 their life-span (Hurley and Weisman, 1954), it is probable that 

 the addition of chromate oxidizes other substances in the red 



