IMMUNITY AND ANAPHYLAXIS 209 



Fleming's modification is to use the hemolytic immune- 

 body in human serum for sheep's corpuscles, and thus he 

 can use the complement in the patient's blood. This 

 simplifies the process. 



D'Este Emery uses human red cells, sensitized with 

 heated immune serum from a rabbit which has been 

 injected with human cells. , He advises only 5 minutes' 

 incubation in a water-bath at 38 C, which very appre- 

 ciably shortens the time taken for the test. 



Browning, Cruickshank, and McKenzie describe " a 

 method of carrying out the reaction which is very reliable 

 in practice, and depends on the fact that the amount of 

 complement absorbed by a mixture of serum and lecithin 

 is increased on the addition of cholesterin, if the serum is 

 syphilitic ; but not, if the serum is normal. Accordingly, 

 two series of tests are carried out simultaneously in the 

 one, complement is added to the mixture of serum and 

 lecithin ; in the other, to the mixture of serum, lecithin, 

 and cholesterin. If more complement is absorbed in 

 the second series than in the first, then the reaction is 

 positive." 



Value of the Test. Like the agglutination or Widal 

 test for enteric fever, the fixation of complement or 

 Wassermann test for syphilis has its limitations. 



It is almost always negative in healthy subjects, but 

 quite often gives a positive reaction in those suffering from 

 leprosy, scarlet fever, jaundice, yaws, sleeping-sickness, 

 and the acute stage of malaria. 



In the primary stage of syphilis, a negative result is 

 usually got in the first fortnight. Thereafter one may 

 expect a positive resjilt in 50 per cent of the cases, and 

 its absence has some weight. 



In the secondary stage, in the presence of a suspected 

 rash, a positive reaction is got in 50 to 70 per cent of 

 the cases. 



In the tertiary stage, with progressive lesions present, 

 the absence of the reaction is almost conclusive proof that 

 another diagnosis than syphilis must be sought. 



In later stages, a positive reaction shows that the patient 

 is not cured. Does a negative reaction show that he is. 

 cured ? If a positive reaction was got previously, then it 



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