686 STUDIES ON EOSIN HEMOLYSIS 



to red blood cells against the toxic action of eosin, leads us to believe 

 that we are dealing with a special type of oxidation which is markedly 

 accelerated by fluorescent substances. The highly specific action of 

 tyrosine and tryptophane as reducing agents likewise indicates that 

 these amino-acids which are contained in the protein molecule are 

 attacked and undergo oxidation as a result of the photodynamic 

 action of eosin. It is not possible at this time to state how far 

 this oxidation proceeds or the mechansim whereby lysis takes place. 

 It appears logical to assume that the oxidation concerns itself with 

 the proteins of the stroma and this results in the necrosis of the cell 

 (13). ^ 



Bo vie (14) has demonstrated that coagulation of proteins can be 

 brought about by exposure to ultra-violet light. This reaction is 

 presumably one of denaturation (15) and does not involve oxidation. 

 To eliminate the possibility of denaturation being a factor in eosin 

 hemolysis, the following experiment was carried out: a test-tube 

 containing 2 cc. of horse serum and 0.1 cc. of 1 : 1,000 eosin was exposed 

 to sunlight for a period of 4 hours and subsequently incubated at 37° C. 

 There was no visible coagulation. 



SUMMARY, 



Additional experimental work on the subject of eosin hemolysis 

 has been carried out. This indicates that red cells may be protected 

 against the toxic action of eosin in sunlight by the presence of inorganic 

 reducing agents. It is pointed out that a marked parallelism exists 

 between the substances which react with the Folin and Denis reagent 

 and the compounds which afford protection to red cells against the pho- 

 todynamic action of eosin. The property which is possessed in com- 

 mon by all of the substances is that they are easily oxidized, and their 

 ability to protect red cells lies in their power of reduction. The toxic 

 action of eosin probably involves the oxidation of tyrosine and trypto- 

 phane which are contained in the protein molecules of the stroma. 



