The Influence of Salt-Concentration on Haemolysis. 397 



It is of interest to note that Muir and Browning have shown that the 

 addition of sodium chloride to fresh serum, in quantities sufficient to inhibit 

 the hsemolytic action of complement, also prevents the retention of the 

 complement in the pores of a Berkefeld filter. 



The following investigations were undertaken in the hope of throwing 

 further light on the part played by salt-concentration in preventing the union 

 of red cells and complement. 



Attention has been confined throughout to the. action of varying strengths 

 of sodium chloride. 



Sheep corpuscles, three times washed, have been employed as the test red 

 cells, and fresh guinea-pig serum as complement. The inactivated serum of a 

 rabbit, immunised by repeated intravenous injections against sheep's red cells, 

 provided a powerful hsemolytic antibody. 



It seemed desirable to commence by repeating Markl's experiments, 

 amplifying them in certain directions. Without entering into details of the 

 experiments performed, it may be said that Markl's conclusions were 

 entirely confirmed, and that no action of the increased salt-concentration, 

 other than the prevention of the combination of the complement with the 

 .sensitised red cells, could be demonstrated. 



Markl also showed, in the course of his experiments, that by adding 

 increasing amounts of a hsemolytic serum it was possible to produce lysis in 

 the presence of increasing amounts of acid sodium phosphate. He, however, 

 employed an active serum containing hsernolytic antibody and complement, 

 .and made no attempt to investigate these two factors separately. An attempt 

 was therefore made to estimate quantitatively how far the anti-hsemolytic 

 action of the increased salt-concentration could be counteracted by increasing 

 the concentration of the haemolytic antibody or of the complement. 



The following experiment is a typical one, and the results obtained in it 

 were repeatedly confirmed. 



Experiment. — In this and similar tests, since it was desired to determine 

 the increase in hsemolysis resulting from an increase in complement or anti- 

 body content consisting of a definite number of hsemolytic doses, the guinea- 

 pig serum was first absorbed for 2 hours at 0° C. with excess of sheep 

 corpuscles ; and a preliminary series of tests was put up to determine the 

 minimal hsemolytic dose of this absorbed serum. 



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