154 PRACTICAL METHODS IN IMMUNITY 



ment which will entirely haemolize the red cells in one-half an hour in water bath 

 equals one unit of complement. For the test use two units of complement. 



THE WASSERMANN TEST. 



In the Wassermann reaction the rabbits are injected with sheep 

 red cells which have been washed twice with salt solution by aid of the 

 centrifuge. About five injections with, on the average, the quantity of 

 red cells contained in 5 c.c. of sheep blood given at intervals of five days 

 gives a strong haemolytic serum if taken about one week after the last 

 injection. The method is to take in a test-tube 0.2 c.c. inactivated 

 human serum (heated for one hour at 56 C.), o.i c.c. fresh serum from 

 guinea-pig for complement, i unit antigen and 3 c.c. normal salt solu- 

 tion; then to incubate for one hour at 37 C. (An antigen unit is the 

 amount that will inhibit haemolysis of i c.c. of 5% emulsion of sheep 

 cells when mixed with 0.2 c.c. luetic serum and o.i c.c. guinea-pig comple- 

 ment.) Then add 2 units of amboceptor and i c.c. 5% emulsion of 

 sheep red cells, shake and incubate for one hour. (The amount of 

 haemolytic serum that will haemolize i c.c. of a 5% emulsion of sheep 

 red cells to which o.i c.c. guinea-pig serum has been added, in one hour, 

 is an amboceptor unit.) 



The same technic is employed with the control test-tube except that 

 the antigen unit is not put in. 



The Noguchi method gives a positive reaction with nonsyphilitic 

 sera in about 7% of cases. The Wassermann gives a negative result 

 in about 9% of syphilitic sera. These figures show the advantage of 

 checking one against the other. 



There seem to be certain sera when with a clinical history of syphilis we 

 obtain a positive Wassermann with unheated serum and a negative one with 

 inactivated serum. In order to obtain information with the same serum heated 

 and unheated I would recommend, when it is inconvenient to carry out the original 

 Wassermann technic, to employ the Noguchi technic with inactivated serum and 

 the Emery technic with fresh unheated serum. In any case when serum cannot be 

 tested within twenty-four hours it should be inactivated, as unheated serum tends 

 to become anticomplementary. 



Cherry thinks anticomplementary bodies are found during chloroform anaes- 

 thesia. If the antigen should also have anticomplementary action the total might 

 give a negative result. 



By heating the serum for half an hour at 56 C. (inactivation) the positive 

 results obtained in certain cases of cancer, nephritis, scarlet fever, leprosy and tuber- 

 culosis may be avoided; the syphilitic antibody alone being thermostable. The 



