682 STUDIES ON EOSIN HEMOLYSIS 



substances were found by Gortner and Holm to include tyrosine, 

 tryptophane, uric acid, a-methyl indole, and ferrous iron. Abder- 

 halden (6) states that the list also includes oxyproline and oxytrypto- 

 phane. The property which is possessed in common by all of these 

 substances is that they are easily oxidizable. 



Experimental work was accordingly undertaken to determine 

 whether inorganic reducing substances in addition to tyrosine, trypto- 

 phane, and proteins which contain these amino-acids in the molecule 

 can afford protection to red cells against eosin hemolysis, and our results 

 appear to answer this question in the affirmative. As in the previous 

 work, 0.5 cc. of a 5 per cent saline suspension of red blood cells (ox or 

 sheep) was placed in each of a number of small test-tubes, and to each, 

 1 cc. of a 1 : 10,000 dilution of eosin (Griibler's) in salt solution was 

 added. The substances to be tested for protective action were like- 

 wise made up in normal saline solution in the concentrations, as given 

 in Table I, and the reaction was adjusted to approximate neutrality. 

 The tubes were placed in direct sunlight for 30 minutes and after 

 exposure they were immediately placed in the ice chest. The tubes 

 were inspected at the end of several hours to determine the amount of 

 lysis which had taken place. Control tubes which were kept in the 

 dark eliminated factors other than that of photodynamic action. The 

 experimental results are given in Table I. They indicate that inor- 

 ganic reducing substances afford marked protective action to red 

 blood cells against eosin hemolysis. The list of inorganic reducing 

 substances which may be used in experiments of this type is limited, 

 since many of the best reducing agents such as ferrous chloride, 

 ferrous sulfate, and ferrous ammonium sulfate, yield solutions of high 

 acidity, and when these are added to red cells the latter are aggluti- 

 nated. Oxyproline and oxytryptophane were not available for experi- 

 mental work. It is doubtful whether the former substance can protect 

 red cells against the toxic action of eosin, since gelatin, which contains 

 14 per cent (7) of this substance, lacks protective ability. Marked 

 protection was shown by each of the two preparations of histidine. 

 Both gave a trace of blue color when tested by the Folin and Denis 

 reagent, indicating the possible presence of tyrosine. Valine, serine, 

 proline, creatinine, and cinnamic acid afford no protection, while 

 marked protection is afforded by skatole and tryptophane. 



